The Journal of

Volume Gemmolog26 No. 4 October 1998 y

The Gemmological Association and Gem Testing Laboratory of Great Britain Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London EC1N 8TN Tel: 0171 404 3334 Fax: 0171 4048843 e-mail: [email protected] Website: www.gagtl.ac.uk/gagtl President: Professor RA. Howie Vice-Presidents: E.M. Bruton, A.E. Farn, D.G Kent, RK. Mitchell Honorary Fellows: RA Howie, RT. Liddicoat Jnr, K. Nassau Honorary Life Members: D.J. Callaghan, E.A Jobbins, H. Tillander Council of Management: CR. Cavey, T.J. Davidson, N.W. Deeks, RR Harding, M.J. O'Donoghue, 1. Thomson, VP Watson Members' Council: AJ. Allnutt, P. Dwyer-Hickey, S.A. Everitt, R. Fuller, AG. Good, J. Greatwood, B. Jackson, J. Kessler, J. Monnickendam, 1. Music, J.B. Nelson, P.G Read, R Shepherd, P.J. Wates, CH. Winter Branch Chairmen: Midlands - G.M. Green, North West - 1. Knight, Scottish - B. Jackson Examiners: AJ. Allnutt, M.Sc., Ph.D., FCA, 1. Bartlett, BSc., M.Phil., FCA, DCA, E.M. Bruton, FCA, DCA, C.R Cavey, FCA, S. Coelho, BSc., FCA, DCA, Prof. AT. Collins, BSc., PhD, AG. Good, FCA, DCA, G.M. Howe, FCA, DCA, GH. Jones, BSc., Ph.D., FCA, M. Newton, BSc., D.Phil., CJ.E. Oldershaw, BSc. (Hons), FCA, H.L. Plumb, BSc., FCA, DCA, RD. Ross, BSc., FCA, DCA, PA Sadler, BSc., FCA, DCA, E. Stern, FCA, DCA, S.M. Stocklmayer, BSe. (Hons), FCA, Prof. I. Sunagawa, D.Sc., M. Tilley, cc, FCA, CM. Woodward, BSc., FCA, DCA The Journal of Gemmology Editor: Dr RR Harding Assistant Editors: M.J. O'Donoghue, P.G. Read Associate Editors: Dr CE.S. Arps (Leiden), G Bosshart (Zurich), Prof. AT. Collins (London), Dr J.W. Harris (Glasgow), Prof. R.A Howie (Derbyshire), Dr J.M. Ogden (Cambridge), Prof. AH. Rankin (Kingston upon Thames), Dr J.E. Shigley (Carlsbad), Prof. D.C Smith (Paris), E. Stern (London), S.M. Stocklmayer (Perth), Prof. I. Sunagawa (Tokyo), Dr M. Superchi (Milan), CM. Woodward (London) Production Editor: M.A Burland

Vol 26, No.4, October 1998 ISSN: 1355-4565 Blue euclase from Zimbabwe — a review Susan Stocklmayer (née Anderson), FGS, FGA Philip Antrobus Ltd., London

ABSTRACT: Blue euclase from Mwame, Hurungwe District, Zimbabwe, which was first collected in the late 1970s has recently been available for study. This paper presents information on mineral inclusions for the first time and the complex surface morphology of the crystals is shown in a series of photomicrographs.

Keywords: euclase, inclusions, pegmatite, Zimbabwe

Introduction Euclase in Africa uclase, a rare beryllium mineral Tanzania 174 (BeAlSi04 (OH)), occurs worldwide as Spencer (1934) first described euclase a late-stage hydrothermal mineral often from Africa. Spectacular crystals were found associated with beryl and other beryllium with quartz in pegmatite at Lukangasi Mica minerals in a variety of host rocks, usually Claims, 8 km south of Mikese Station, quartz veins, granitic pegmatites or greisens. Morogoro District. The largest of these 209 Although euclase can occur as a primary crystals measuring 72 x 38 x 35 mm (b axis mineral, more usually it is secondary in direction) is in the collection of the Natural origin formed by replacement of other History Museum, London. It is described as beryllium minerals. being white and cloudy but bluish green and First recorded from Brazil in 1785 (Dana, transparent on the face parallel to b. Other 1892; Bastos, 1969), euclase has been found crystals were sold in the 1930s to collections more recently from sources in Colombia, in the USA (Pough, 1991; see also Dirlam et al., Russia, Tanzania and Zimbabwe; spectacular 1992; McKie, 1955). crystals have been described from all these localities. Of less importance gemmologically, Mozambique occurrences with small crystals or non- A reference to the occurrence of euclase transparent types of euclase have been from Muiane pegmatite, Alto Ligonha recorded from New Zealand, USA (Sharp, District, was made by von Knorring et al. 1961), Europe, Guyana, Sri Lanka (Deen, (1964). This pegmatite was mined for micro- 1984), Kashmir, Mozambique, Uganda and lite and tantalite and was an important Namibia. source of gem beryl, producing both Euclase occurs in a range of colours aquamarine and pink beryl; it was also noted including pale green, pale to medium blue, for giant crystals of microcline. Two crystals, medium greenish blue, pale yellow and apparently similar in morphology to the colourless; the gemmological interest in the Zimbabwean euclase were described, one crystals from Zimbabwe is for the deep azure was used for analysis, and the other colour. reportedly weighed about 20 gm. No

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 minerals, herderite and bertrandite. Beyer inferred that the euclase formed after a first generation of beryl but was older than the tabular crystals of bertrandite. The associated euclase and herderite showed no signs of etching or dissolution and euclase was not considered to be the source of beryllium for a younger generation of beryl (aquamarine) which also occurred in the pegmatite.

Uganda In a report by von Knorring (1962) on the mineralogy of pegmatites in Uganda, euclase was recorded in the Namapherere tin mine, Ankole. Beryl is a common minor constituent in all the pegmatites mined in south-west Uganda and at Kihandu mine, an unusual form of beryl with acute bipyramidal form Figure 1: Partial euclase sheath on beryl crystal. has been pseudomorphed by muscovite and Photo: E.A. Jobbins albite together with crystals of clear flaky bertrandite. No further information was information was given about the found on this locality. 209210 accompanying minerals or the paragenesis of the euclase. Zimbabwe Euclase has been found in several of the Namibia pegmatites mined for mica since the 1920s and A report by Beyer (1980) described colour­ for beryl since the 1950s in the Mwame area less to slightly yellow crystals up to 5 mm long 19 km NNE of Karoi, in northern Zimbabwe from Spitzkopje. The euclase grew freely on (Figures 1, 2, 3 and 4). These occurrences are microcline together with quartz, green described in more detail in this paper. feldspar, fluorite, and the other beryllium Euc1ase in Zimbabwe Figure 2: Group of euclase crystals, each about 10 mm across. Photo: E.A. Jobbins History Euclase was first recorded in Zimbabwe in 1952, from a location 16 km east of Mwame (Geological Survey, 1952) and again (Wiles, 1961) where it is mentioned in a review of the economic minerals of the Mwame Mica Fields, Hurungwe District. Mwame was formerly known as Miami, Urungwe District, Rhodesia or Southern Rhodesia; most references cited give the earlier names, which are used in this paper where. relevant. Euclase is one of a group of rare beryllium minerals that had been found in pegmatites in this area; hurlbutite and herderite occur in the Grand Slam Beryl mine, phenakite in an unnamed beryl working and chrysoberyl in the Renda mine. No bertrandite

J. Gemm., 1998, 26, 4, 209-218 has been recorded. Only chrysoberyl and euclase have been exploited commercially. The crystal aggregates and faceted gems of blue euclase described in 1978 (Gübelin) 1980 (Anderson) and in this paper, came from the Last Hope claims located on Haslemere and Momba Estates 13 km NNE of the town of Karoi. Recent information unsupported by geological reports refers to the production of some euclase specimens from the MWM claims, Haslemere and Momba Estates and from Trim, Mukwichi District. Both localities are within the general Mwame area. Samples of euclase at the Geological Museum, Harare, are recorded from the Eurythmie and Lion Hill claims, situated N and NNW of Mwame; the euclase from Last Hope claims, however, remains the Figure 3: Faceted euclase, 4 mm across. Photo: SM. Stocklmayer most significant source for the blue variety. Euclase specimens displayed in mineral collections at the Natural History Museum, granite plugs termed the Miami Granites. London, and the National Museum of Radiometric data gave K-Ar ages of 520 and Scotland in Edinburgh, originate from the 530 Ma on muscovite from the Catkin and Last Hope claims. Esquire pegmatites (Wiles, 1961) and K-Ar and Rb-Sr ages of 480 ± 20 Ma and 500 ± 20 Ma on biotite from the Miami 209211 Geology Granites (Clifford et al, 1967). The country rocks are sillimanite gneisses and sillimanite garnet schists; formed by Figure 4: Faceted euclase of Figure 3 immersed high-grade metamorphism of former to show the colour distribution. Photo: SM. argillaceous sediments of the mid- Stocklmayer Precambrian Piriwiri supergroup. There have been several metamorphic episodes, the most significant phase being the Palaeozoic to Proterozoic (400-650 Ma) event referred to as Miami metamorphism (Stagman, 1978). Pegmatites are of two main groups representing distinct episodes in the metamorphic history of the area. An 'older' group, secretionary in type and unzoned, are composed principally of plagioclase, quartz and some tourmaline and belong to a phase of sodic metasomatism; these are of no economic importance. The 'younger' group include the economic pegmatites and belong to a later potassic phase of metasomatism considered to be part of the Miami metamorphic event. These pegmatites contain abundant microcline and may also have mica, beryl and other gem species. They are clearly associated with late kinematic intrusive

Blue euclase from Zimbabwe - a review The nature of the mineral content of these recrystallization and replacement of pegmatites is complex with source material pre-existing beryl by secondary euclase. The not only derived from the granites but, in the mineralogical sequence of replacement was case of the mica-bearing type, from described in a preliminary report (Anderson, assimilated country rock. The close 1980). association of the economic mica-bearing The Last Hope pegmatite, located 8 km pegmatites and the nature of the enveloping SW of Mwame, was first pegged for mining country rocks demonstrates the mica sometime soon after 1920. The metamorphic control. This was noticed by pegmatite intruded along a normal fault, early prospectors and miners who called the discordant to the foliation of the host gneiss, country rocks 'kindly' schists which were and displaced a barren tourmaline host to 'mellow' mica-bearing pegmatites. In pegmatite. Late faulting and movement them, mica often formed large blocks related to the nearby intrusive Miami Granite perpendicular to the strike of the pegmatite produced bent beryl crystals and buckled in the contact and border zones. mica in some local pegmatites and faulting is Not only are pegmatites composite in demonstrable in some of the larger euclase derivation but also may contain simple or crystals. Small-scale fissuring of euclase complex mineral zones. Late pneumatolytic crystals has resulted in fractures, later filled activity, resulting in kaolinization of the with fine-grained mica and iron-stained clay. feldspars, is considered to have provided a During its productive life, the mine was suitable environment for the crystallization exploited for mica on five levels, the fifth level of tourmaline, beryl and other species such at 85 m below surface; the longest drive was as the blue topaz (St Ann's claims) and for on the third level and had total length of 347 m. The width of the pegmatite ranged from 1.5 to 4 m. Mining ended in 1959 with a 212209 Figure 5: Euclase crystal with mica 'booklet' projecting from base and showing 'hour glass' total production of cut mica of 225 tonnes. colour distribution. Photo: SM. Stocklmayer Only a small amount of beryl, 0.44 tonnes, was declared in 1953 but this may have originated from nearby claims. This production of beryl included blue and yellow varieties; there was no gemstone industry at the time and all production was classed as commercial. The section of pegmatite from which euclase was collected is a few metres west of one of the old mine shafts. The pegmatite is approximately 2.5 m wide, strikes parallel with the country rocks but dips more steeply. It is simply zoned with marginal areas containing 'fish tail' mica developed perpendicular to the strike of the pegmatite, together with anhedral quartz, iron-stained kaolin and tourmaline. Beryl crystals were located in the core in a matrix of iron-stained kaolin, muscovite and quartz; this zone was also penetrated by 'blows' of quartz. Euclase occurs with the beryl as well as in association with quartz (Fey, 1978). The euclase samples were extracted loose from soil and overburden by digging, hand- sorting and washing the rubble. Single, doubly terminated crystals and crystal

/. Gemm., 1998, 26, 4, 209-218 aggregates were released from the reddish clay soil by washing, while other crystals were loosened from the vugs of massive samples. The excavation was small and covered only a few metres and mining stopped when barren quartz was exposed. The pit was refilled and never reopened. Before these claims were officially pegged and worked, illegal mining at the site accounted for the appearance of samples in 1977 and early 1978.

Crystal morphology The Last Hope euclase occurs in two distinct habits; in crystal aggregates and massive. Massive euclase is intimately associated with beryl and progressive replacement of beryl by euclase can be demonstrated in a series of pétrographie sections (Figure 1). Figure 6: Euclase crystal with a euhedral quartz Euclase in bladed, flattened and blocky crystal on its surface. Photo: SM. Stocklmayer habits may be present on the surface of beryl crystals as a sheath. In other samples replacement of beryl has been complete and rare, and confined to the veins traversing the perfect pseudomorphs have resulted, beryl or between crystals of euclase. 209213 preserving hexagonal prismatic form; one of The blue colour of euclase is evident in thin these measures 115 mm across. The outer section under plane polarised light (PPL) and surface of the pseudomorph may also be pleochroism is distinct from blue to colourless. coated with massive white translucent The blueness occurs in small patches with no quartz and white mica (Figure 5) and may be apparent pattern to its distribution. cavernous with vugs lined with euclase The beautiful specimen crystals of euclase crystals. Some massive euclase has small occur commonly as groups of well-formed straight gashes in the surfaces; these terminated prisms, patchily transparent and penetrate to a depth of several mm and it blue with colourless zones. Some of the seems likely that they were occupied by mica crystals appear cloudy, with surfaces booklets. Feldspar occurs on the surface of encrusted with quartz (Figure 6). The some samples but is not common. development of euclase seems to be partly The crystals of euclase of this massive type concurrent but generally later than the quartz; each cover several cm and can be seen quartz crystals may have an encrustation of surrounding and traversing areas of relict euclase and similarly crystals of euclase beryl. The remnant beryl has ragged borders contain quartz euhedra which comprise the and is penetrated by numerous veinlets of most common mineral inclusion. euclase in optical continuity, providing clear The largest well-formed euclase crystal in evidence for progressive replacement of the the group of specimens studied measured beryl. These large anhedral euclase crystals 74 mm x 42 mm x 47 mm (fr-axis); however, commonly contain inclusions of small quartz this is exceptional and most of the crystals, perfectly hexagonal prismatic in terminated crystals are less than 10 mm in form and random in distribution, producing a their largest dimension. The deep-blue sieve texture. No strain patterns were evident colour that appeared patchy in thin section in the enclosing euclase. Mica inclusions are may display a coherent pattern in certain

Blue euclase from Zimbabwe - a review Figure 7: 'Hour glass' colour distribution or zonation in a euc/ase crystal. Photo: S.M. Stocklmayer

zones of the crystals. The most intense blue is seen as a series of vertical planes, parallel to the a-faces (l00) perpendicular to the b-face (010) and diminishing in length towards the 209214 crystal centre. Viewed from the direction of the b-face this produces a distinct 'hour Figure 9: Circular depressions on a (100) face of glass' colour distribution (Figures 5 and 7). euc/ase. Photo: R. Huddlestone Viewed from the direction of the a-faces a

chevron pattern of intense blue is often seen Figure 8: Complex surface morphology of a zone at the crystal apices more or less parallel to between the a and c axes of a euc/ase crystal. The the (011/021) prisms (clinodomes). view is taken looking down a and shows the terracing. Photo: R. Huddlestone Euclase crystals are monoclinic prismatic in habit, almost equant, slightly flattened parallel to (l00) with perfect cleavage (010). Crystals comprise broad pinacoids (l00) and (OlD) and prisms (011) and (021); the latter are usually featureless and unmarked. In contrast the c-zone intergrowths between vertical prisms (hkO) and pinacoids (010) are commonly striated (Figure 8), and in the complex zone between the a and c crystallographic axes (hkl, hOI) terracing is common. An unusual feature comprising a series of circles with micropit centres was found on the (l00) face of one euclase crystal (Figure 9). The circular features may be the result of solution activity. Terracing has been described in equivalent zones in euclase crystals from

J. Gemm., 1998, 26, 4, 209-218 (a)

step in sspectrumpectrum duedU"Ofilt~g10 ftIl~"

3lJOnm300nm 750nm7SOnm

215 (b)

step in spectrumpectTUm due to filter change due to fill~"~ _

300nm300nm 750nm

Figure10:Figure 10: Absorption spectra (a) parallel and (b) perpendicular to the c-axis ofaof a euclase crystal from the Last Hope mine.

Blue euclaseeuc/ase from Zimbabwe - a review Analysis of euclase from the Last Hope claims using a MAC 5 - SA5 electron microprobe indicates that the blue zones contain 0.06% Fe as FeO; titanium was detected in only one blue zone near detection

levels at 0.02% Ti02 (Mattson and Rossman, 1987). These authors also inferred from a study of the beta-polarized spectrum that the colour can be attributed to charge transfer Fe2+ - Fe3+ and Fe2+ - Ti4+ transitions. A 670 nm spectral absorption band was assigned specifically to Fe2+ - Fe3+ charge transfer. Gübelin (1978) reported that colourless parts of the crystals contain 0.06% FeO and dark-blue parts contain 0.12% FeO and concluded that trivalent iron is the cause of the blue colour. No absorption bands were visible in the hand-held optical spectroscope, the spectrum showing transparency in the 450 nm region. Figure 10 shows the results of a spectrophotometer scan on euclase from the Last Hope. The crystal was positioned 216209 first to transmit the light parallel to the Figure 11: Slender euhedral quartz crystal c-axis and secondly in a position at right- inclusions in euclase. Photo: SM. Stocklmayer angles to show the results produced by a combination of vibration directions. The broad transmission transparency in the blue Brazil (Graziani and Guidi, 1980). The region attains a maximum in the range terraces have developed parallel to the 380-460 nm with a gradual increase in junctions (hkl)-(hkO) and (hkl)-(100) and absorption in the red with a maximum in the contain rows of discrete mineral inclusions. range 650-670 nm. Micro pits are also a feature in the (hkO) faces of some of these Brazilian crystals. Inclusions in euclase Optical features and chemistry Worldwide sources Euclase crystals are monoclinic, normal There is little published information class and holohedral, with an axial ratio about inclusions in euclase. a : b : c of 0.84:1:1.55. Refractive indices In euclase from Santa do Encoberto, measured on a faceted stone were a -1.652, Minas Gérais, Brazil (Graziani and Guidi, ß-1.656, y-1.672, all ± 0.001 (Na) with a 1980), black inclusions of hematite were birefringence of 0.020 which values are noted along terraces of the crystal surfaces. within the range recorded by Gübelin (1978). Hematite and 'rounded' zircon grains are Trichroism is distinct from deep blue, to pale described as inclusions formed before the blue to colourless. euclase, and subhedral opalite and rutile Specific gravity was measured in the needles are considered as syngenetic. These range 3.06-3.13 (Gübelin, 1978), 3.075 inclusions were identified using an electron (Anderson, 1980) but the crystals lack microprobe, as their small size precluded mineral homogeneity. identification by optical means.

J. Gemm., 1998,26,4,209-218 Photomicrographs of three-phase surfaces of euclase crystals as well as entirely inclusions in euclase from Colombia have enclosed within as a syngenetic generation of recently been reported (Duroc-Danner, 1996), inclusions. These inclusions may form and their appearance is reminiscent of aggregations so dense that the host crystal inclusions in emeralds from the same country. appears cloudy. In a few crystals they also From various descriptions of occurrences of occur alone or in small groups. No euclase worldwide, several pegmatite crystallographic control of their distribution minerals are described in association with is apparent either macroscopically or euclase, e.g. fluorite, muscovite, quartz, albite microscopically in Norway (Strand, 1953). However, none are reported to occur as mineral inclusions. These Mica reports are of a geological nature where the The occurrence of white mica commonly study of inclusions was not carried out. encrusting the surfaces of the beryl pseudomorphs has already been discussed. Zimbabwe Books of white mica are found on the surfaces Gübelin (1978) examined a suite of of or partly enclosed by euclase crystals. In faceted Zimbabwean euclase and described some crystals, laths of a dark coloured mica healed fissures with no particular orientation were found. Fine-grained white mica and clay or distribution and epigenetic 'dry' fissures minerals occur in fractures and negative showing colour iridescence, but noted no crystals but further work is needed to identify mineral inclusions. Photographs of the precise species. Zimbabwean euclase by Hochleitner (1989) showed crystal faces studded with quartz. Opaque minerals The writer noted that only the colourless Three kinds of opaque minerals have been parts of the crystals are clear and that the seen as rare inclusions in euclase. Two occur 217 blue zones contain liquids that make them 209 as euhedral-subhedral equant grains, one cloudy and opaque. All crystals, including type with yellow brassy metallic lustre, likely those of the finest quality, show colour to be pyrite, the other with a grey-silver zonation and this feature together with metallic lustre. In one crystal, dark mica perfect cleavage (010) are potential problems foliae are associated with these grains. in faceting the gem. When correctly Grains of similar appearance were seen in orientated the faceted gem can appear a some of the larger quartz crystals that are uniform blue, but oil immersion reveals the intergrown with euclase. patchiness of the blue colour. Two-phase inclusions are common, but show no The third kind of opaque inclusion preferred distribution. Although terracing is consists of groups of dark granules which a common feature of the external faces of the appear red-brown in reflected light. crystals, no feature equivalent to axial tubes common in beryl was seen. Discussion The intimate association of euclase and Mineral inclusions quartz is constant and interesting. Their The range of mineral inclusions reflects the synchronous crystallization indicates that the genetic mineral association of quartz, mica conditions necessary for their formation are and euclase found in the surrounding rocks. very similar and that some small fluctuations may determine which phase is developed; quartz occurs both as syngenetic inclusions Quartz in euclase and as surface encrustations. That Quartz is the most common inclusion the two minerals are physically compatible is (Figure 11). Clear and glassy crystals, usually shown optically by the lack of strain and doubly terminated, occur clustered on the stress-induced fissures around the quartz

Blue euclase from Zimbabwe - a review withiwithinn ththee euclaseuclasee crystals.. ThThee surfacesurface Deen,, M.N.M.N.,, 19841984.. RarRare gemstonegemstoness ooff SrSrii Lanka.. LapidaryLapidary encrustationencrustationss araree similasimilarr ttoo ththee Journal,Journal , 38 (1)(1),, 238–4238-400 Dirlam,, D.M.D.M.,, MisiorowskiMisiorowski,, E.B., TozerTozer,, R.,, StarkStark,, K.B., aanndd quartz-epidote-magnetite mineral 'dust' quartz-epidote-magnetite mineral 'dust' BassettBassett,, A.M.A.M.,, 19921992.. GeGemm wealtwealthh ooff TanzaniaTanzania.. GemsCems & adherinadheringg ttoo aquamarinaquamarinee describedescribedd bbyy EppleEpplerr Gemology,Cemologtj, 2288 (2)(2),, 80-10280-102 (1963(963)) whwhoo suggestsuggestss temperaturetemperature Duroc-DannerDuroc-Danner,, J..M.J.. M.,, 19961996.. EuclasEuclasee frofromm ColomColombibia fluctuationfluctuationss aass ththee likellikelyy causcausee foforr ththee showinshowingg three-phasthree-phasee inclusionsinclusions.. J.Gemm,rCemm, 2255 (3)(3), 175-6175-6 vari-crystavari-crystall showershower.. EpplerEppler,, W.F., 19631963.. SomSomee observationobservationss oonn aquamarinee andand quartzquartz.. J.Gemm.,rCeml11 ., 9 (1)(1),9-16, 9-16 MininMiningg ceaseceasedd aatt ththee LasLastt HopHopee claimclaimss aatt FeyFey,, P., 19781978.. The Lastt HopHopee (euclase(euclase)) claimsclaims,, MombMombaa farm,farm, ththee enendd ooff 19781978.. IItt iiss likellikelyy thathatt furtherfurther UrungwUrungwee DistrictDistrict.. UnpubUnpub.. RhodRhod.. GeolGeol.. SurvSurv.. TechTech.. files occurrenceoccurrencess ooff euclaseuclasee wilwilll bbee discoverediscoveredd bubutt GeologicaGeologicall SurveSurveyy ooff SoutherSouthernn RhodesiRhodesiaa AnnuaAnnuall RReporeportt 19519522 prospectinprospectingg requirerequiress carefucarefull searcsearchh bbyy mineraminerall Graziani,, G.,, anandd GuidiGuidi,, G.G.,, 19801980.. EuclasEuclasee frofromm SantSantaa do collectorcollectorss ratheratherr thathann commerciacommerciall miners.. Encoberto,, MinaMinass GeraisGerais,, BrazilBrazil.. AmAmericanerican Mineralogist,Mineralogist , 6655 (1–2)(1-2), 1183–83-77 GübelinGobelin,, E.E.,, 1978.1978. SaphirblaueSaphirblauerr EuklaEuklass - einein AcknowledgmentAcknowledgmentss SammlersteinSammlerstein,, Z.Dt.Z.Dt. Gemmol.Cemmol. Ges.,Ges., 2277 (3)(3),, 145-50145-50 HochleitnerHochleitner,, R.,, 19891989.. BlaueBlauerr EuklaEuklass auauss ZimbabweZimbabwe.. Lapis,Lapis, GratefuGratefull thankthankss araree extendeextendedd ttoo RalpRalphh ReReaa 10/810 /89924-8 24-8 ooff ZimbabweZimbabwe,, formeformerr owneownerr anandd mineminerr ooff ththee MattsonMattson,, S.M.S.M.,, anandd RossmanRossman,, G.R.G.R.,, 1987.1987. IdIdentifyinentifyingg LasLastt HopHopee claimsclaims,, forfor ththee samplesampless loaneloanedd forfor characteristiccharacteristicss ooff chargchargee transfetransferr transitiontransitionss inin thithiss investigationinvestigation;; StepheStephenn KennedKennedyy aatt ththee mineralsminerals.. Phys.Phys. Chem.Chern. Minerals, 1414,94-9, 94-9 McKieMcKie,, D.D.,, 19551955. NoteNotess oonn somsomee mineralss fromfrom GAGTGAGTLL foforr ththee spectrspectraa ooff euclaseeuclase;; AlaAlann TanganyikaTanganyika.. Records Geol.Ceol. Survey Tanganyika V, 881-1-77 JobbinJobbinss foforr photographphotographss anandd RoRoyy PoughPough,, F.H.F.H.,, 1991.1991. EuclaseEuclase.. Lapidary Journal, 4455 (2), 13-1613-16 HuddlestonHuddlestonee foforr ththee photographphotographss ooff crystacrystall Sharp,, W.N.W.N.,, 11961961.. EEuclasuclasee inin greisengreisen pipepipess andand asassociatesociatedd surfaces;surfaces; anandd finallfinallyy ttoo VernoVernonn StocklmayerStocklmayer depositdepositss ParParkk CoCountyunty,, ColoradoColorado.. AmAmericanerican Mineralogist,Mineralogist, 4466 (11–12)(11 -12), 11505–505--88 andand IanIan KirkpatrickKirkpatrick,, formeformerr colleaguecolleaguess ofof ththee Spencer,, L.J.L.J.,, 11934934.. BerylliuBerylliumm mineralmineralss (euclase aanndd GeologicaGeologicall Survey,Survey, Zimbabwe,Zimbabwe, foforr valuablevaluable phenakite)phenakite) from AfricaAfrica.. MineralogicalMineralogical Magazine,Magazine, 23, 218209218 adviceadvice andand editorialeditorial assistanceassistance givengiven iinn ththee 141466,6, 616–216--23 preparatiopreparationn ooff thisthis report.report. Stagman,, J.G., 1978.1978. AAnn outlinoutlinee ofof ththee geologygeology off RhodeRhodesiasia.. Rhod. CeoGeol.l. Surv. Bull., 8080 Strand, T.,T., 1953.1953. EuclaseEuclase fromfrom Iveland, Iveland, occurring occurring as asan analteration alter­ ReferencesReferences ation pproducroductt off berylberyL. Norsk. Ceol.Geol. Tidsskrift, Tidsskrift, 31 3 (H.I.)1 (H.I. 1)-5 1– 5 von Knorring,Knorring, O., 0., 1962. 1962 The. The mineralogical mineralogical aspects aspects of the of the AAndersonnderson,, S.M.,S.M., 1980.1980. Euclase.Euclase. Jr . Cemm.Gemm.,, 1717 (1),(1), 18-2918-29 pegmatite off the AltoAlto LigonhLigonhaa area,area, MozambiquMozambiquee.. Bastos, F.M.,F.M., 1969.1969. EuclaseEuclase fromfrom MinasMinas Gerais,Gerais, Brazil.Brazil. ResResearcearchh InInstitutstitute ofof AfAfricaricann GeologyGeology.. UniversitUniversityy off rJ . Gemm.,Cemm., 1111 (8)(8),312-14, 312-14 LeedLeedss,, SixthSixth Annuall RReporteport,, 7-97–9 BeyerBeyer, H.,H., 1980.1980. MineralbeobachtungenMineralbeobachtungen anan derder kleinenkleinen vonvon KnorringKnorring,, 0O..,, SaSahamahama,, ThTh.G..G., anandd SaarSaarii,, E., 1964. A SpitSpitzkopjizkopjiee (SWA). Aufschluss,Aufschluss, 3131 (1),4-(1), 4-332 notenote on euclaseeuclase fromfrom MuianMuianee mine, AltAltoo Ligonha, Clifford,, T.N.,T.N., Rex, D.C., andand SSnellingnelling,, NN.J..}.,, 19619677. Mozambique.. FinlFinlanandd Corom.Comm. Geol.Geol. B.B. 22115 Soc.Soc. GeoGeoll.. Radiometric ageage datadata forfor the Urungw Urungwe andand MiamiMiami FinlandFinlandee, C.C.RR.. no.no. 36,36, 1143–43-55 ggraniteranitess ofof Rhodesia.Rhodesia. Earth and PlaPlanetarynetary Science Warner, S.MS.M..,, 1972.1972. CheckCheck lilisst ofof ththee minerals ofof RhRhodesiaodesia.. LLettersetters,, 2,2, 5-125-12 Rhod. Ceol.Geol. Surv. Bull., 69,69, 3232 DDanaana,, EE.S..S.,, 1892.1892. The system of minmineralogyeralogy (6(6tthh edn.)edn.) Vol.Vol. IIII Wiles, J.W.,J.W., 11961961.. The geogeologlogyy ofof thethe MiamiMiami Mica FieldField Silicates.Silicates. MineralMineral DataData PubliPublishingshing, TucsonTucson (Urungwe District)District).. South. Rhod. Ceol.Geol. Surv. Bull.Bull.,, 5151

J.J . Grmm.,Gemm., 1998, 2626,, 4, 209209–218- 218 Further aspects of the history of rose-cut diamonds Herbert Tillander, FGA Helsinki, Finland

ABSTRACT: The development of rose-cut diamonds in centres such as Antwerp and Amsterdam is discussed. Suggestions for a realistic terminology are made.

Introduction variety of new diamond cuts. Consequently it is likely that they will also have hit on the n the recent treatise on historical idea of stepping cleavages and other suitable diamond cuts (Tillander, 1995), rough, a trick which, since the mid-sixteenth J I corrected early, long-lived, mis­ century, they had successfully performed on understandings regarding the development crystals not thick enough for perfect table of the brilliant cut, but did not pay the same cuts. This stepping was found to disperse attention to the obviously parallel situation light entering from above and consequently 219 with reference to the rose cut. Consequently I to increase the light effects, but also, by trial spent the summer of 1997 reading everything and error, they went on to create the ideal I could possibly find on this cut. facetings and proportions. My prime disclosure is that the rose cut We may never be able to find out when cannot have been developed from surviving the prototypes were created, including their primitive hexagons by gradually adding original outline and height proportions, if facets. In the Dutch encyclopedia on diamonds these events coincided with the catastrophic of 1908 (Leviticus and Polak, 1908) I found the and destructive invasions by the Spaniards. clear statement that both the hexagonal and In addition, the following depression forced square rose cuts had been experimental only many cutters to re-establish in Amsterdam and turned out to have been abortive. and records are often lost in such Consequently neither could have served as a movements. In these circumstances, serial starting point. Max Bauer, writing in 1896 and production of this new cut would have been 1909, and Karl Schlossmacher initially in 1932 postponed. This was consequently the in the sequence named 'Edelsteinkunde', were beginning of diamond cutting in the ones who established the concepts about Amsterdam, but we do not know which of rose cuts. Ever since, they have been the two competitors will have been in the uncritically repeated. It is therefore high time position to market the full range of rose cuts to correct early misunderstandings. in large quantities, if not both. In any case we find that from 1625 rose cuts had already been available for some Development of the rose cut time. They were, however, simply described Since the early fifteenth century, as faceted diamonds (faucets by some) and beginning in Bruges, the Flemish cutters named as rose cuts only by the end of the have been unequalled creators of a great seventeenth century. This was the reason

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 have been competitive enough with the Some notes on Antwerp cutters. When the river Scheide was Thomas Gletscher 1598-1668 closed in 1648 Antwerp was forced to rely exclusively on Amsterdam for deliveries of Cletscher was Crown Jeweller to rough. In order to put a stop to Antwerp's Prince Frederik Hendrik in the Hague, a supremacy the Amsterdam dealers offered specialist in gem setting and a financier. only rejection qualities such as coloured, In 1625 he began to reproduce diamond flawed and hard-to-master goods. The cuts in jewellery, which in various ways victims of this treatment did not, however, passed through his hands. For some give up. On the contrary, the situation was undisclosed reason he concentrated on excellently mastered. First of all the height of the 'new-fangled' rose cuts. Although he the rose had to be substantially lowered, foils omitted mentioning the provenance of were adopted for reducing the effects of off- the diamonds, Cletscher's collection of coloured rough, and finally inclusions were drawings fortunately turned out to be disguised by switching some facet ridges. the prime and priceless source of reliable Contrary to what has been alleged, they information on cuts from 1625 onwards. retained the full number of facets, except on On his fifty drawings of jewellery with stones too small to accommodate them. The roses he depicts a wide range of roses cutters in Amsterdam simply concentrated (sometimes classified into seven types on higher quality and larger sizes with near on the basis of facet pattern), every to ideal proportions, but nevertheless conceivable outline and a great variety continued to produce some stones with of applications, many fairly soon irregular outlines. These circumstances abandoned. prevailed at least until 1668 when there was Most pages of Cletscher's notebook a generally chaotic market situation and 220209 have gone astray, but those surviving in Holland reduced its diamond trade to a the Museum of Boymans-van Beuningen minimum. At that time Antwerp would then in Rotterdam, suffice as a source of most likely have found some kind of access information about early rose-cut to the developing London market for rough jewellery. More details on jewellery of of any quality. the period can be found in the book The terms Antwerp and Amsterdam as Juwelen en Mensen by M.H. Gans applied to rose cuts were, even though published in 1961. incorrectly defined, relevant, but only for a relatively short period. In practice they differed mainly in that the former were why they had only occasionally been considerably shallower, being described as mentioned in this period as 'a rose fashioned spread roses. Recently, on a two-day visit to out of one crystal'. As late as 1673 such a cut Moscow, I was shown their entire collection was described as 'an oblong, thin diamond of thousands of roses, mostly spread. Not with large facets and a flat bottom7. Any one of them had less than the standard earlier documentation of rose cuts has not number of facets, obviously with the yet been found. Those rose cuts present in exception of the exceedingly small ones. On earlier jewellery, such as on the Fellowship reflection, this is not really surprising Pendant in the Grünes Gewölbe (see because it would take more time to leave Tillander, 1995, p. 54) are now found to be open spaces than to apply regular facets all later replacements of some insignificant the way round. stones (such replacement was a regular habit The rose cuts were originally based on also in the Schatzkammer in Munich). At cleaved dodecahedral crystals. The two some (so far unknown) stage, rose cutting halves of the cleaved crystal formed the was obviously introduced also in initial point of departure for the cutter. They Amsterdam, but the cutters appear not to resemble consequently the shape of a

J. Gemm., 1998,26, 4, 219-221 flat-bottomed triangular cupola. Quite obvi­ 3. Baroque roses or simply rose cuts or roses ously this called for a pattern of faceting with Flat-bottomed, stepped diamonds with threefold symmetry. It also explains the triangular facets in threefold symmetry, a variety of regular and irregular outlines crown with six facets coordinating with which, for weight-saving reasons, followed the outline of the stone and, in principle, the outlines of the rough. 18 facets at the base (see also Tillander, With the introduction of brilliant cuts, 1995, pp 45, 52 and 54-63). roses gradually lost their popularity and most of the large ones were refashioned into Conclusion brilliants. Small roses were mostly used as complementary stones surrounding central The ultimate reason for this paper is, brilliant cuts and coloured gems. By the however, to influence the gemmological nineteenth century they were already out of institutions the world over in their use of date, but occasionally rehabilitated for suitable terminology when referring to rose- specific purposes. In Fabergé jewellery about cut diamonds, to refrain from unhelpful or 1900, costly gems were totally excluded and, even incorrect statements such as on visiting the Green Vaults in Dresden, Carl 'originating in India7, 'double roses' or Fabergé will no doubt have been influenced 'rounds only'. by the specific charm of minor roses, set in There is also no sense any longer in succession, and decided to try this naming roses Antwerp or Holland roses, arrangement out on his Easter eggs. On since at times both centres delivered Fabergé's platinum and gold egg of 1914 the whatever type their customers were looking cost price paid for the extraordinary number for. It is far clearer and more understandable of 1782 roses was only 75 kopeks each. Even to describe a rose as high or spread. so, this amounted to only 5 per cent of the total cost of material used in its manufacture. In future, gemmologists should be able to 209221 The size of the stones is generally below correctly name most historic cuts and give 1 mm, but there are three larger irregular full exposure and value to their interest as lozenges on the outsize crown each with six collectors' items. more or less rectangular facets round their I finally suggest that both gemmologists bases. and historians refrain from using the trade vernacular 'polished'. In most other languages polishing stands for 'the final Summary of rose cuts touch on the scaife'. Several authors have Rose cuts may be considered in three already replaced 'polished' with 'fashioned' main categories: or 'faceted'. Neither of these latter terms can be misunderstood. 1.Gothic roses Flat-bottomed diamonds with a great References variety of facet shapes, mostly trihedral, Bauer, M.H., 1896. Edelsteinkunde. Tauchnitz, Leipzig created in the early fifteenth century and Bauer, M.H., 1909. Edelsteinkunde 2nd edn. Tauchnitz, still popular throughout the sixteenth (see Leipzig also Tillander, 1995, pp 45-52); Bauer, M.H., 1932. Edelsteinkunde 3rd edn. revised and rewritten by K. Schlossmacher. Tauchnitz, Leipzig Cletscher, T., c. 1625. Sketchbook. Museum Boymans-van 2.Renaissance roses or rosettes Beuningen, Rotterdam Gans, M.H., 1961. Juwelen en Mensen. J.H. de Bussy, Combination of from 4 to 16 pavé-set and Amsterdam pavilion-based diamonds marketed as Leviticus, F., and Polak, H., 1908. Geillustreerde Encuclopaedie complete settings which may easily be der Diamantnijverheid. De Erven F. Bohn, Haarlem Tillander, H., 1995. Diamond cuts in historic jewellery fixed on any suitable piece of jewellery 1381–1910. Art Books International, London. (see also Tillander, 1995, pp 87-98); ISBN 1 874044 07 4

Further aspects of the history of rose-cut diamonds Kyanite in diamond identified by Raman analysis John I. Koivula and Shane Elen Gemological Institute of America, Carlsbad, California, USA

ABSTRACT: This paper describes the identification of kyanite and garnet as inclusions in a round brilliant-cut diamond. Kyanite is a very rare inclusion in diamond, and this is the first time Raman analysis has been used to make such an identification. It is an effective analytical technique and both the host diamond and inclusions remain undamaged.

Introduction largest blue crystal was weak, showing blue and violet. Previous descriptions in the n 1994, during the routine examination literature (Prinz et al, 1975; Meyer and Tsai, of a 0.65 ct round brilliant-cut diamond 1976) indicated that this inclusion might be J to determine its clarity grade, kyanite, which is a very rare inclusion in 222 gemmologist Gary Roskin of Los Angeles, diamond. It was also thought that the California, noticed what appeared to be a isotropic orange crystal was a garnet and, if 209 small blue crystal inclusion just under the both these interpretations proved to be table facet near the edge of the diamond's correct, it is likely that the diamond came crown. Since this was the first blue mineral from an eclogite. inclusion in a diamond that he had seen, he contacted one of the authors (JIK) and, with By coincidence, N. Sobolev from the permission of the owner, submitted the Novosibirsk, Russia, was visiting the GIA gem for further examination. and was able to examine the stone. He also concluded that in all probability the blue Under magnification it was noted that the crystals were kyanite and that the orange diamond actually contained three blue crystals ranging in size from 0.15 to 0.42 mm in largest dimension. The diamond also Figure 1: This 0.42 mm blue inclusion in diamond was identified as kyanite by laser Raman contained several transparent colourless microspectrometry. crystals and an orange crystal measuring 0.3 mm in length. While the two smallest blue crystals were very pale in colour, the largest one showed a rather intense blue when viewed at a slight angle to the plane of the table, through the edge of the crown (Figure 1). Polarized light microscopy revealed that the blue crystals were doubly refractive, as were the colourless crystal inclusions. But no signs of double refraction were observed in the orange crystal. The pleochroism of the

© Gemmological Association and Gem Testing Laboratory of Great BritainISSN: 1355-4565 crystal was an eclogitic garnet. He based this the plane of the glass slide. This allowed the conclusion on his observations of similar- inclusion to be focused with minimum risk appearing kyanites he had examined from to the surface of the 50x objective lens of the xenoliths of eclogite and grospydite (a rock Leica targeting microscope. composed of grossular pyroxene and dzsthene Using the continuous scan feature, the - or kyanite). Sobolev also stated that this Raman system was set up for 10 complete diamond was a significant stone because of scans of the inclusion. The 514 nanometre its inclusions and suggested that the argon ion laser was used to obtain the Raman diamond be purchased for destructive spectrum shown in Figure 2. The search analysis, to determine if the blue inclusions programme was then employed using the were in fact kyanite. Such analysis procedure Raman software in conjunction with the would require burning the diamond away in Renishaw digital spectral library. The oxygen, or some other destructive technique, computer selected a spectral match for to free the mineral inclusions so that they kyanite. could then be identified. As a back-up to this result, to ensure the A price was settled on and the stone was integrity of the identification, a cabochon of purchased from the pawn shop that owned it kyanite was also analysed with the Raman in Kenmore, New York. However, since a system using the same laser strength and the very strong case for rarity had been made, it same number of scans. Once again the was decided that the stone would not be computer match from the Renishaw digital destroyed but would be held intact until the spectral library was for kyanite. The resulting technology needed to identify the inclusions spectrum obtained from the cabochon is non-destructively became available at the shown in Figure 3. The strengths of the major GIA. With the recent acquisition of a peaks for kyanite vary slightly due to the Renishaw Raman Imaging Microscope host's matrix effect in the case of the inclusion, System the non-destructive identification of and the difference in optical and crystallo- 209223 the inclusions in this diamond has now graphic orientation between the cabochon and become possible. the inclusion. However, all the major kyanite peaks are present, and their positions are Experimental identical, proving that the largest blue inclusion in this diamond is kyanite. In preparation for laser Raman micro- To complement the genetic picture of this spectrometry with the Renishaw system, the diamond, the orange isotropic crystal diamond was first cleaned in acetone and (Figure 4) was also examined with the laser then carefully examined under magnification. Raman microspectrometer. The result of this This was done to determine which of the analysis confirmed what was already blue inclusions was closest to the surface, suspected, that this inclusion was a garnet, and which orientation of the stone would be and its orange colour is a strong indication the most advantageous for the analysis. It is that the host diamond is eclogitic rather than an advantage to direct the laser as near from a peridotite (where the associated perpendicular to a facet as possible so that its garnets are chrome pyrope and pale to traverse through the host gem to the deeply coloured red to purplish-red). inclusion is as short as possible. As it was relatively near the surface (less than 1 mm) and it presented a large blue- Conclusion coloured target area through the edge of the Kyanite is the high-temperature, high- crown, the largest blue inclusion was chosen pressure member of the trimorphous mineral for Raman analysis. The diamond was group of kyanite, andalusite and sillimanite. placed in a special mount on a glass It is known to occur in diamondiferous microscope slide with the chosen target area eclogites and on this basis it is not surprising of the diamond in parallel alignment with to find kyanite as an inclusion in diamond.

Kyanite in diamond identified by Raman analysis r-, .,.00 3000

2500

~ 2000 Ng .J!J c 0 g ~ c-0 u 1500

1000

500

0

200 400 600 800 1000 1200 Raman Shift (cm')

Figure2: The Raman spectrum obtained from thekyaniteinclusion shownin Figure 1. 224

N 5500 :9

r-, 00-e-

5000

.J!J § 0 N U g 'f'" 00 -o ~ 4500 ~ Oli co ;;:5

4000

200 400 600 800 1000 1200 Raman Shift (crrrt)

Figure 3. Raman spectrum from a kyanitecabochon usedas a reference standard.

J. Gemm., 1998,26,4,222-225 But kyanite in diamond is apparently very rare. This rarity may be partly illusory and due at least in part to the fact that the smaller the inclusion of kyanite in diamond, the lighter it is in colour, to the point that the smallest appear colourless. This fact is well demonstrated by the inclusions in the diamond described in this paper. This size­ to-colour dependence would make smaller kyanite inclusions very difficult to recognize . Since most mineral inclusions in diamonds are quite small, some kyanite inclusions have probably been overlooked because they are so small and lack a distinctive colour. The authors were able to find only two previous reports of such an occurrence. The first description is provided by Prinz et al. Figure4. Reflected three times, and measuring (1975) who reported a crystal of about 1 mm only 0.12 mm, this orange garnet is in the same in size exposed on the surface of a cut stone diamond as the kyanite. from an unknown locality. According to Meyer and Tsai (1976) this identification '... must be viewed with caution,' however, host intact to be re-examined and enjoyed at because 'Unfortunately, the identification by any time in the future. Prinz et al. was of the kyanite on a cut surface of a diamond'. In the second description, Acknowledgements Harris and Gurney (1979)reported finding a 225 kyanite inclusion in a diamond from the The authors extend their thanks to Gary Premier Mine. Roskin for calling our attention to this This paper also shows that it is possible, unusual diamond. This study would not in certain instances, to identify mineral have been possible without the generous inclusions in a diamond without burning, support of Mike Scott of Los Altos, cutting, grinding or breaking the host to California, for his donation of the Renishaw expose an inclusion at the surface, which has Raman Imaging Microscope System. been a necessary practice in research for many years. Raman analysis, however, is by References no means the complete answer to inclusion investigation. If inclusions are too deep in Ha rris, J.w., and Gurney, J.J., 1979. Inclusions in diamond. In: Field, J.E. (Ed). Theproperties of diamond. Academ ic their host then they cannot be identified in Press, Londo n. pp 556- 91 this manner. Laser Raman microspectrometry Meyer, H.O.A., and Tsai, Hsiao-Ming, 1976.The nature and also does not give details of chemistry significance of mineral inclusions in natural diamond: a comparable with those from an electron­ review. Minerals Science andEngineering, 8 (4) 242--61 microprobe, and it cannot provide precise Prinz, M., Mans on, D.V., Hlava, P.P., and Keil, K., 1975. Inclusion s in diam ond s: garnet lherzolite and eclogite structural information like that provided by assembl ages. In: Physics and chemistry of the Earth , Vol. X-ray diffraction. However, it does leave the 9. Pergamon Press, Oxford and New York, pp 797-815

Kyanite in diamond identified by Raman analysis Tourmaline: morphological and compositional variations during the growth history of uvite single crystals

Yasushi Takahashi and Ichiro Sunagawa Yamanashi Institute of Gemmology and Jewellery Arts, Tokoji-machi 1955-1, Kofu, 400 Japan

ABSTRACT: Surface microtopographs of crystal faces, internal textures and associated compositional variations have been investigated on single crystals of uvite from Brumado, Bahia, Brazil. From the surface microtopographic observations of major faces, it is demonstrated that the uvite crystals grew by the spiral growth mechanism, and the growth rate in the positive direction was about twice as high as in the negative direction. Based on the investigations of internal textures including growth sectors, sector boundaries and growth banding, the morpholog- ical and compositional evolution during the whole growth history was analysed, and four stages where morphological changes took place were distinguished. In the first stage, crystals were bounded principally by r 226 and r'{10Tl}, but in the second stage [010], [110] and [100] sections (probably corresponding to either r and r' or r and m, m' {10T0}) appeared, which was associated with an increase of Mg contents. The appearance and development of a{1120} faces at the third and fourth stages were associated with a decrease of the uvite component. At the earlier stages of growth, the uvite component was high, and the dravite compo- nent increased in the later stages, reflecting compositional changes of the fluid formed by the action of granitic fluids on the original carbonate rocks. There was no partial dissolution at any period during the growth history nor was there any excessive increase of the driving force at the latest stage, and the whole growth proceeded and terminated rather gently

Keywords: compositional variation, growth history, growth mechanism, morphological evolution, single crystal, tourmaline, uvite

Introduction are typically seen in the form of sector or ourmaline is a mineral which typically colour zoning and growth banding. Beautiful shows morphological, compositional examples may be seen in the monograph by Tand colour changes during its growth Benesch (1990). history. In sections cut perpendicular or Tourmaline is also a representative polar, parallel to the elongation of a prismatic crystal hemimorphic crystal. It shows different of elbaite of pegmatitic origin, such changes development of faces in positive and

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 negative directions of the c-axis. Usually one The composition is expressed in mole ratio of end is terminated by trigonal pyramidal uvite and dravite end members. Although faces, whereas the other end is characterized there is a report that Fe can be a component by a basal face. One may often find a group of this series, the name uvite is, in this of tourmaline crystals all pointing in the paper, applied to those compositions with positive direction or all in the negative Ca > Na, since no Fe was detected in the direction, but only rarely does one find a samples. group with the two directions coexisting. In Uvite crystals typically exhibit a flat previous works on polarity of tourmaline rhombohedral (equant) to short prismatic crystals, somewhat controversial observations habit terminated in both positive and have been reported; some papers reported negative faces. They show similar internal that the growth rates were higher in the textures to those observed in elbaite. Uvite positive direction, whereas other papers typically occurs in carbonate rocks contact reported the higher growth rates for the metasomatized by an intrusion of acidic negative direction (Dietrich, 1985). It is (granitic) magma (Dietrich, 1985) where the known that surface microtopographs of crystals often occur as isolated single crystals, crystal faces can tell much about growth not in a group. Such crystals are suitable for mechanism and the difference of growth detailed investigations of their surface rates in different directions (Sunagawa, microtopographs and internal textures. In 1988b), but such investigations on this paper, we report the results of tourmaline have not been reported so far. investigations on the external morphology, Tourmaline crystals typically showing surface microtopography of crystal faces, morphological, compositional and colour morphological and compositional evolution changes in a single crystal, such as elbaite during the growth history of uvite single crystals of pegmatitic origin, usually have an crystals from Brumado, Bahia, Brazil, elongated prismatic habit bounded by purchased from a mineral dealer in Belo 227209 heavily striated vicinal prism faces, and the Horizonte. Altogether 15 crystals were terminal faces are often corroded. These investigated. make elbaite crystals unsuitable for detailed We intended to analyse how and by what observations of their as-grown features. mechanism the uvite crystals grew and how Crystals formed in pegmatitic environments morphological and compositional evolution have usually been subject to repeated partial took place in the contact metasomatic dissolution and re-growth processes during environment. The methodology and results their growth histories. The evidence for such of the present analyses may be applicable, in processes has been found in various essence, to the features commonly observed pegmatitic minerals, e.g. beryl, topaz and in other elbaite crystals of pegmatitic origin. quartz (see, for example, Sunagawa, 1982, 1984a, 1988a; Scandal, 1996), and pegmatitic tourmaline is no exception. It is probably due Crystal morphology and polarity to this fact that the growth mechanism and The uvite crystals are brownish-green in process, as well as morphological and colour in transmitted light. They occur as compositional changes of tourmaline crystals doubly terminated and isolated single through their growth histories, have so far crystals with a flat rhombohedral (equant) to not been investigated in detail. short prismatic habit bounded by well Uvite is the Ca end member of the dravite developed positive and negative trigonal

[(NaMg2Al6B3Si6027(OH,F)4] - uvite [CaMg3 pyramidal faces, r{10Tl} and r'{0lïï}, (Al5,Mg)B3Si6027(OH,F)4] series (Dunn, second-order prism faces a{1120}, and a basal 1977). Dravite and uvite form a continuous face, c'{000T}. Much smaller m{10T0} and solid solution through the coupled substitution m'{0lT0}, o'{022T}, e'{01Ï2}, and t'{213T} Na+ + Al3+ <-• Ca2+ + Mg2+, although the pure faces are also associated (Figure la). The well end member uvite has not yet been reported. developed crystal faces are macroscopically

Tourmaline: morphological and compositional variations during the growth history of uvite single crystals 228 209174

Figure 1: (a) Crystal figures. Orthogonal projection of positive (top) and negative (bottom) terminations, and (centre) clinographic projection, (b) Close-up photographs of positive (top) and negative (bottom) terminations of a crystal.

flat or striated, but microscopically show Tiny rhombohedral magnesite crystals are growth step patterns resembling the contour the only paragenetic mineral, suggesting a lines on a geographical map. contact metasomatic origin of the specimens. The polarity of the crystal was identified by Kundfs method (1883). Three r{10Tl} faces Surface microtopography appear on the positive termination, whereas The surface microtopographs of all faces on the negative termination c'{000Ï} and three were observed by the differential interference r'{0lïï} faces appear. The prism zone consists microscope (DIM), which can reveal growth of six well-developed, flat a{1120} faces and six steps with step heights of the order of much smaller m and m'{1010} faces. Figure 1 nanometers (Sunagawa, 1988b). The surfaces shows the crystal figure and close-up were coated with silver under vacuum to photographs of a uvite crystal showing secure high reflectivity so that steps of one positive and negative terminations. nanometre height could be observed.

J. Gemm., 1998,26,4,226-237 (a) c +

(b)

229 174 Figure 2: SurfaceSurface 209229 microtopographsmicrotopographs ofof positivepositive (a)(a) andand negativenegative (b)(b) trigonaltrigonal pyramidalpyramidal faces,faces, rand r and r';r'; sketchessketches preparedprepared based on microscopic observations at low c- observations at low magnification.magnification.

Trigonal pyramidal faces, r{lOll}rflOll} and GrowtGrowthh hillockhillockss oonn positivpositivee rr facefacess araree r'IOlïî}r'{Olll} elongateelongatedd paralleparallell ttoo ththee shorteshorterr diagonadiagonall ooff PositivPositivee anandd negativnegativee trigonatrigonall pyramidalpyramidal,, rr ththee faceface,, i.ei.e.. [211][211],, whicwhichh iiss ththee reasoreasonn foforr ththee anandd r'r',, facefacess exhibiexhibitt markedlmarkedlyy differendifferentt surfacesurface macroscopimacroscopicc appearancappearancee ooff striationsstriations.. UndeUnderr microtopographsmicrotopographs,, aass cacann bbee seeseenn iinn Figure 2.2. highighh magnificationmagnification,, thetheyy cacann bbee seeseenn ttoo bbee AlthougAlthoughh positivpositivee trigonatrigonall pyramidapyramidall rr facefacess elongateelongatedd growtgrowthh hillockshillocks,, witwithh plateaplateauu topstops.. appeaappearr macroscopicallmacroscopicallyy aass striatestriatedd facesfaces,, thetheyy OOnn sucsuchh plateaplateauu topstops,, a numbenumberr ooff extremelextremelyy araree microscopicallmicroscopicallyy featurefeaturedd bbyy ththee thithinn circulacircularr growtgrowthh stepstepss araree discerniblediscernible,, developmendevelopmentt ooff growtgrowthh hillockhillockss havinhavingg a ververyy aligninaligningg iinn ththee directiodirectionn perpendiculaperpendicularr ttoo ththee elongateelongatedd spindlspindlee forformm witwithh aann aspecaspectt ratiratioo elongatioelongationn ooff ththee growtgrowthh hillockhillock,, i.ei.e.. iinn ththee largelargerr thathann 1010,, whereawhereass negativnegativee facefacess havhavee a [010[010]] zonezone.. SomSomee ooff ththee circulacircularr growtgrowthh stepstepss smallesmallerr numbenumberr ooff growtgrowthh hillockhillockss witwithh shoshoww spiraspirall patternpatternss witwithh a halhalff oorr a couplcouplee ooff rhombirhombicc forformm concordanconcordantt witwithh ththee edgeedgess ooff turnsturns.. ThiThiss iiss seeseenn iinn a high-magnificationhigh-magnification ththee faceface.. AlAlll ooff thesthesee featurefeaturess araree as-growas-grownn DIDIMM photographphotograph,, Figure 3a, anandd ththee featuresfeatures,, anandd dissolutiodissolutionn featuresfeatures,, sucsuchh aass etcetchh correspondincorrespondingg sketchsketch,, Figure 3b, 3b, where wher ecircular circula r pitspits,, werweree nonott observedobserved.. stepstepss araree indicateindicatedd bbyy arrowsarrows.. AlthougAlthoughh ththee

Tourmaline:Tounnaline: morphological and and compositional compositional variations variations during during thethe growth growth historyhistory ofof uvite uvite singsinglele crystals crystals c + c + + +

...... 230 3 3

(a) (b)

Figure 3: (a) High-magnification photomicrograph taken ona differentialinterferencemicroscope(DIM) showing growth hillocksona positivetrigonal pyramidal r fa ce,and (b)thecorres pondingsketch. Small arrowsindicate elemental circulargrowth steps. Straight lines are faint cracks running perpendicular to the elongation of growth hillocks.

f. Cemm., 1998, 26, 4, 226-23 7 height of the circular growth steps could not be measured directly, it is safe to assume that they are elemental steps with the height of the d{10Tl} lattice spacing, judging from the visibility under DIM (Sunagawa, 1988b). On the side slopes of elongated hillocks, growth steps are seen with an average step separation of 2.6 urn, whereas the average step separation in the elongation is 11.3 urn. It follows from these observations that the positive trigonal pyramidal r faces grew most probably by the spiral growth mechanism, and that elemental growth spirals took a circular form, rather than polygonal or elongated spindle forms at their Figure 4: A sketch of growth hillocks on an centres. The elongated spindle form of the a(1120)face. growth hillocks develops through interaction and merging of circular growth spirals. concordant with the outline of the face In contrast to the above, on the negative (Figure 4); they exhibit gentler sloping sides trigonal pyramidal r' faces, rhombic growth towards the positive direction and steeper hillocks are seen. The hillocks show plateau ones in the direction of the negative axis tops, with two sides which are steeper which is towards the edge with the toward the direction of negative polar axis neighbouring m or m' face (see Figure 4). and two gentler sloping sides in the positive direction. Even on the steeper side, the Basal face, c'{0001} and minor faces 209231 average step separation is more than 5 urn, The basal face is an undulating face with more than twice that on the positive trigonal many polygonal cavities resulting from pyramidal r faces. It was not possible to detachment of magnesite crystals, and does confirm the presence of elemental growth not show any step patterns. Other minor spirals on the plateau top, but it is reasonable faces, o'{022T}, e'{0lT2}, t'{213Ï} are rough, to assume that the growth hillocks are spiral showing no step patterns. hillocks from their morphologies. Circular or rounded morphology of growth steps on positive trigonal pyramidal r faces in Internal textures contrast to the rhombic morphology on Method of observation negative trigonal pyramidal r' faces, and twice Sections perpendicular to and parallel to the average step separation on r' compared the c-axis of a crystal were prepared to with r can be taken as an indication that the observe internal textures under a polarizing growth rate in the positive direction was more microscope, and to investigate variations in than twice that in the negative direction. chemical compositions using an electron probe micro analyser (EPMA). Both point Prism faces, a{1120} and m and m' {1010} analyses (at 7 points) and line scans along six lines were made on the two sections. The second-order prism faces a{1120} develop as much larger faces than the first- order prism faces m and m'UOÏO} (Figure 1). Section perpendicular to the c-axis On the a{1120} faces, rectangular growth More than 40 photomicrographs were hillocks are seen, whereas the m and m' faces taken to prepare a mosaic photograph to show either simple striations or undulating visualize the internal textures. Each surfaces with no step pattern. Rectangular photograph was taken at a slightly rotated growth hillocks on the a{1120} faces are position from the extinction to reveal the

Tourmaline: morphological and compositional variations during the growth history of uvite single crystals TableI: EPMA pointanalyses ofa uvite crystaltogether with gemmological data.

Stage 2 3 4 Point 2 3 4 5 6 7 8 9 w t %

Si0 2 37.45 37.63 37.39 37.71 37.45 37.28 37.93 36.01 36.17

Ti02 0.57 0.53 0.60 0.52 0.64 0.48 0.52 0.55 0.66 AlP3 29.54 28.61 28.84 28.80 28.45 28.49 30.29 26.36 28.87

Cr203 0.08 0.06 0.07 0.06 0.04 0.03 0.08 FeO 0.06 0.02 0.02 0.02 0.07 0.05 0.01 0.49 1.65 MnO 0.00 0.03 0.00 0.01 0.00 0.01 0.00 MgO 13.36 14.00 13.76 13.49 13.84 13.52 13.16 14.90 12.23 N iO 0.01 0.00 0.00 0.05 0.02 0.00 0.00 CaO 4.15 4.53 4.23 3.79 4.10 3.62 2.65 5.09 2.81

Nap 0.66 0.53 0.63 0.74 0.67 0.76 1.18 0.35 1.26 Kp 0.02 0.03 0.01 0.00 0.00 0.00 0.02 Tota l 85.90 85.97 85.55 85.19 85 .28 84.24 85.84 83 .75 83 .65

Uvite % 78 82 79 74 77 73 56 91 50

NB: Corresponding growth stages 1 to 4 are shown. Positions of analytical points are shown in Figure 5. 8 and 9 show maximum and minimum data of uvite component in Dunn (1977). 232 Contents of B, F, OH were not determined.

RI: 1.610-1.628 Birefringence: 0.018 SC: average 3.04 Pleochroism: dichroic (strong) green, yellowish-green Fluorescence: inert Spectroscope: Cr lines are difficult to discern Chelsea colour filter: red Magnification: magnesite inclusions, liquid film i CB

internal texture most clearly. This procedure Since the internal textures revealed on the was necessary because optical properties, mosaic photograph are too faint to be including extinction angles, vary from point reproduced, only the corresponding sketch to point even in a single crystal. This of the observed internal texture is presented phenomenon in tourmaline crystals was in Figure 5. Boundaries of growth sectors reported as early as in the last century (a sector formed by the growth of a particular (Madelung, 1883), and more recently face) and their changes during the growth investigated by Foord and Mills (1978). Such history, as well as growth banding in some variations in optical properties within a sectors are discernible under the microscope. single crystal have been attributed to crystal From the observed pattern, there are three growth processes, which itself is an distinct features relating to the growth interesting problem for further investigation. process of the uvite crystal. The problem has been treated in terms of First, there is no peripheral mantle 'vicinal sectoriality' by Chernov (1984), or portion with fibrous texture. Such mantles 'intrasectorial zoning' by, for example, are common in pegmatitic tourmalines and Scandal (1996), but we shall not deal with their fibrous texture has been attributed to a this problem in the present paper. rapid increase of driving force with a

J. Gemm., 1998, 26, 4, 226-237 during the growth history of the uvite crystals may also be correlated with changes in their compositions. 1. The earliest stage 1, i.e, the central portion of the crystal, is characterized by a triangular outline bound by [010], [110] and [100] directions. In this stage, the most developed faces were positive and negative triangular pyramidal rand r' faces, and the habit was rhombohedral. Whether or not m and m'{lOIO} faces were present cannot be concluded from stage this section only, but certainly no a(1120) ... 2 faces were present. 2. The second stage takes a hexagonal Figure 5: Internal textures (growth sectors, sector boundaries, directions of growth banding outline, bounded by [010], [110], [l00], andgrowth stages) seen in a section perpendicular [100], [010] and [110] directions. It is not to the c-axis. Growth stages are shown by certain whether the six sectors corre­ different colours, growth banding by dotted lines, sponding to positive r and negative r' and other boundaries by solid lines. Numbers trigonal pyramidal growth sectors alone, correspond to analytical points in Table 1.A-A', or whether they are associated with the B-B', C-C' and D-D' are line scans . Arrowed growth sectors of m and m'{lOIO) faces. solid lines indicate ranges of respective growth 3. The third stage takes a 12-sided outline, sectors, a, r + m, r' + m' , characterized by the development of a{ll20) faces. 233 consequent increase in growth rate and 4. In the final stage 4, narrow growth sectors associated morphological changes at the corresponding to smaller m and m'{lOIO) final stage of crystallization (Sunagawa, faces appear, in addition to the a(1120) 1984a,b, 1988a); this is a feature also growth sectors. commonly observed in the phenocrysts of volcanic rocks and in coated diamonds. Lack of a fibrous mantle in the uvite crystals is an Compositional variation indication that crystal growth proceeded Table I gives the results of point analyses rather gently from beginning to end of their in the cross-section, together with growth history, keeping the polyhedral corresponding growth stages, reference morphology. This indicates that there was no chemical data and gemmological data. The abrupt change in the growth parameters at contents of the major oxides, SiOz' Alz0 3, the latest stage, which might have induced a MgO, CaO and Nap, and uvite mole % are drastic change of morphology from polyhedral given. It can be seen in Table I that Ca and Mg to dendritic. show concordant variation, whereas Al and Na show reverse variation with Ca and Mg, Secondly, no rounded discontinuous indicating coupled substitution. Figure 5 boundaries which intersect growth sectors shows the analysis points and where the were seen. This indicates that there were no EPMA line scans (A- N, 8-B', C-C', D-D') periods of intermittent partial dissolution were carried out. during the growth process of the uvite Figu re 6 shows relative variation in crystals. contents of Mg, Ca and Na along each scan Thirdly, from the sequence of changes in compared with the centre. From these growth sector boundaries and growth variations, changes in uvite mole ratios have banding, the following four stages have been been calculated. From Table I and Figures 5 distinguished. The morphological evolution and 6, we note the following:

Tourmaline: morphological and compositional variations during thegrowth historyof uvite singlecrystals 4. In the fourth and final stage, the CaO content decreases by almost 2 wt%, and

the Na20 content increases by about 0.5 wt% (almost doubling), i.e. the uvite component sharply decreases in all growth sectors in the fourth stage. In the sections parallel to the c-axis distinct growth sectors are not easily discernible under a polarizing microscope, and only faint features may be visible. However, from the results of EPMA analyses, the following compositional variations were established: 1.Compositional variation similar to that noted at the boundary between the second and third stages in the cross- section is present along the whole Figurée: Compositional changes based on the periphery of the crystal, with a constant results of EPMA line scans. Relative changes in width of less than ca. one-fifth of that of the contents ofMg, Ca and Na are shown, taking the prism. Mg and Ca contents decrease the respective contents at the centre as standard. towards the periphery whereas the Na Boundaries of growth sectors and stages are also content increases, i.e. the uvite component indicated. decreases and the dravite increases both perpendicular and parallel to the c-axis, at 234209 1.At the boundary of the triangular outline the onset of the third stage, where a{1120} of stage 1, there are slight decreases of less faces started to develop. than 1% in Mg and Ca contents, i.e. the 2.The width of prismatic growth sectors is uvite component decreased temporarily. much narrower than those of trigonal 2.In the second stage, an increase of Mg pyramidal growth sectors, and limited to content (less than 1 wt% MgO) occurs the peripheral portion, about one-fifth of simultaneously with the appearance of the prism. [100], [010] and [110] directions 3.Judging from the compositional variation (corresponding to the growth sectors of r and the form of the growth sectors, the and r', or r + m and r' + m'). In these initial point of uvite growth is situated at growth sectors, an increase of Ca and a about one-third of the length along the decrease of Na, both being less than 1 wt% prism and closer to the negative end. of the oxides, occur simultaneously with the increase of Mg. There is a general increase of In Figure 7a and b, growth sector the uvite component at this stage. boundaries, growth stages and variations in uvite component are summarized and 3.In the third stage, Mg and Ca start to schematically illustrated, in sections decrease and Na increases only in the perpendicular and parallel to the c-axis, a{1120} growth sectors, and this coincides respectively. with the appearance of this face. Meanwhile Mg continues to increase in the growth sectors corresponding to [010], Discussion [110] and [100], where an increase of Mg had already been noted in the second Salient points revealed in this study are: stage. In other words, the appearance of 1. Uvite contents of the tourmaline changed the a{1120} growth sectors is closely from Uv78 - Uv82 - Uv74 - Uv56 from the related to a decrease in uvite and an initial stage to the latest stage of growth of increase in the dravite component. the single crystals.

/. Gemm., 1998,26,4,226-237 2.Morphology of the crystals changed from flat rhombohedral (or equant) bounded principally by r{10ïl} and r'{0111} faces to short prismatic bounded by r{10ïl}, r'{0lïï}, c'{000T} and a{1120} faces during the growth history. Four stages were distin­ guished in the morphological evolution. 3.The appearance and development of a{1120} faces at the third stage are related to an increase of the dravite component. However, morphological changes in other stages are not directly or clearly related to compositional changes. 4.The major portion of the uvite prism was formed by growth on positive and negative trigonal pyramidal faces, r and r'. Growth on the prism faces contributed to the volume of a uvite crystal by less than one- fifth in terms of the width of a prism. 5.The growth rate along the c-axis in the positive direction was about twice as high as in the negative direction. 6.The spiral growth mechanism operated most probably on both positive and negative trigonal pyramidal faces, r and 209235 r', and also on second-order prism a faces, but probably did not on the c'{000Ï}, m, m'UOÏO} and other faces. Based on the above summary, we will now Figure 7: Schematic diagrams showing changes analyse how uvite crystals grew and what in uvite components in mole % and morphological were the causes for morphological evolution. evolution and growth stages in sections perpendicular (a) and parallel (b) to the c-axis. The chemical formulae of dravite and Numbers in (a) indicate uvite mole %. Trends of uvite are NaMg3Al6B3Si6027(OH,F)4 and increase and decrease of uvite components are CaMg3(Al5,Mg)B3Si6027(OH,F)4, respectively, distinguished by different colour lines. The dot in forming a continuous solid solution between (b) indicates the initial point of growth. Both (a) the two end members (Deer et al., 1966). and (b) are perspective projections. Among the major components in these formulae, Ca and Mg are clearly derived from the original carbonate rocks, whereas from the original rocks were consumed at the Na, Al, B, Si, OH, F are considered to come earlier stages, and those from the acidic from acidic magma. The observed changes in magma became gradually enriched. This is uvite-dravite components during the growth reasonable, considering the reaction taking history of uvite crystals suggests that the place between the original carbonate rocks crystals were formed at the beginning from a and acidic magma. fluid enriched in the compositions derived The formation of uvite crystals from a from the original rocks. However, towards fluid phase, not by solid-state reaction, is the later stages of crystallization, Mg and Ca supported by their well-formed idiomorphic diminished, whereas the dravite component morphology, an indication of freely derived from the acidic magma was developed crystals. The fact that uvite enriched. In other words, the components crystals occur in isolation, not in a radiating

Tourmaline: morphological and compositional variations during growth history of uvite single crystals group, indicates that the nucleation rate was and grew under a small driving force low. This implies that the nucleation took place condition. The uvite component in the under a relatively small driving force. Uvite fluid was relatively enriched in the early growth proceeded throughout its history stages of growth, but decreased in favour under such a condition, and neither partial of dravite in the later stages. dissolution during the growth process nor a 2.Initially, uvite crystals were bounded prin­ rapid increase of the driving force at the latest cipally by positive and negative trigonal stage took place. Nucleation and growth pyramidal faces r and r', but later when the proceeded and finished in a gentle growth uvite component diminished, second-order environment. Spiral growth is the most likely prism faces a started to develop. growth mechanism under such conditions 3.Uvite crystals grew by the spiral growth (Sunagawa, 1984a). The undulating surface mechanism on positive and negative features of other faces imply that they trigonal pyramidal r and r', and second- appeared temporarily through the agencies of order prism faces, a. mechanisms other than spiral growth or two- dimensional nucleation growth. These 4.Growth was twice as rapid in the positive features appear on faces by an adhesive-type c-axis direction as in the negative growth mechanism on rough interfaces or by direction, a feature which is reflected in selective impurity absorption (see, for the differences of step separation and example, Sunagawa, 1988a). morphology of growth steps. 5.The driving force changed rather During the morphological evolution from monotonously during the whole process stages 1 to 4, the appearance and dominant of growth. There was no abrupt change in development of second-order prism faces the growth conditions, such as to cause a{1120} at the onset of stage 3 are clearly partial dissolution during the growth related to compositional change from a uvite- process or rapid increase of the driving 236209 rich to a more dravite-rich composition. The force at the final stage. change in morphology occurring at the onset of stage 3 was very distinct; up to that point, the major habit-controlling faces were r{1011}, Acknowledgements r'{0lTT} and c'{000ï}, and possibly narrow m We acknowledge the help of Professor and m'flOK)} faces, with a{1120} faces being E. Horikoshi, O. Ujike and Dr S. Ohtou of entirely absent. The initial morphology Toyama University for using the facilities probably represents the morphology of and discussions about EPMA analyses. crystals of uvite composition, whereas the Thanks are also due to Professor T. Miyata of appearance of a{1120} faces is attributed to an our Institute for the discussions. increase of dravite component. It has been proven in the present study References that the growth rate in the positive direction Benesch, F., 1990. Der Turmalin. Eine Monographie. along the c-axis is twice as high as in the Urachhaus, Stuttgart, Germany Chernov, A.A., 1984. Modern crystallography III, crystal negative direction. Why there is a higher growth. Springer-Verlag, Berlin, Germany, 193-5 growth rate in the positive direction should Deer, W.A., Howie, R.A., and Zussman, J., 1966. An be related to the structural characteristics of introduction to the rock forming minerals. Longman the tourmaline crystal and this is a subject of Group Ltd., London re-investigation and future study. Dietrich, R.V., 1985. The tourmaline group. Van Nostrand Reinhold C.I., New York, USA Dunn, P.J., 1977. Uvite, a newly classified gem tourmaline. J.Gemm., 15(6), 300-8 Summary Foord, E.E., and Mills, B.A., 1978. Biaxiality in 'isometric' 1. The uvite crystals were formed and grew and 'dimetric' crystals. Amer. Mineral., 63, 316-25 Kundt, A., 1883. Uber eine einfache Methode zur freely in a fluid phase derived from the Untersuchung der Thermo-, Actino- und reaction between carbonate rocks and Piëzoëlektricitat der Krystalle. Weidmann Ann. Phys. acidic or granitic magma. They nucleated Chem., 20, 592-601

J. Gemm., 1998, 26, 4, 226-237 Madelung, A., 1883. Beobachtungen mit Breithaupts Polarisationsmikroskop. Zeit. Kryst., 7, 73-6 Scandale, E., 1996. Growth and sector zonings. In: Lecture notes of short course on crystal growth in earth sciences. Santa Victoria d'Alba, Italy, 14-19 April 1996, 176-94 Sunagawa, I., 1982. Gem materials, natural and artificial. In: LONDON DIAMOND Kaldis, E. (Ed.), Topics in materials science, Vol. 10. North- Holland, Amsterdam, The Netherlands. 356-493 REPORT Sunagawa, I., 1984a. Growth of crystals in nature. In: Sunagawa, I. (Ed.), Materials Science of the Earth's interior. Terra Sci. Pub., Tokyo/D. Reidel, Dordrecht. 63-105 Sunagawa, I., 1984b. Morphology of natural and synthetic diamond crystals. In: Sunagawa, I. (Ed.), Materials Science of the Earth's interior. Terra Sci. Pub., Tokyo/D. Reidel, Dordrecht. 303-30 Sunagawa, I., 1988a. Morphology of minerals. In: Sunagawa, I. (Ed.), Morphology of crystals, Part B. Terra Sci. Pub., Tokyo/D. Reidel, Dordrecht. 511-87 Sunagawa, I., 1988b. Surface microtopography of crystal The faces. In: Sunagawa, I. (Ed.), Morphology of crystals, Gem Testing Part B. Terra Sci. Pub., Tokyo/D. Reidel, Dordrecht. 321-65 Laboratory

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Tourmaline: morphological and compositional variations during thegrowth history of uvite single crystals Maxixe-type colour centre in natural colourless beryl from Orissa, India: an ESR and OA investigation

George Mathew1, R.V. Karanth1, T.K. Gundu Rao2 and R.S. Deshpande3 1. Department of Geology; MS University ofBaroda, Vadodara - 390 002, India 2. RSIC, in, Powai, Mumbai - 400 076, India 3. Isotope Division, BARC, Trombay, Mumbai - 400 085, India

ABSTRACT: A change in colour of colourless beryls to green to greenish-yellow on irradiation is reported for the first time from Indian samples. On heating to 300°C/ the colour of the irradiated beryl changes from greenish-yellow to yellow and finally to colourless at 500°C. On the basis of Electron Spin Resonance (ESR) and Optical Absorption (OA) studies, the cause of colour is deciphered to be due to the formation of a defect centre similar to the Maxixe type, and radiation-induced oxidation of Fe2 r present at the octahedral Al3+ site with associated ultra- violet charge transfer (UVCT) tail. The former gives rise to blue and the latter to yellow colours in beryl. A combination of the above two results 238 in a greenish-yellow colour. A new weak additional ESR line at 1500 gauss is reported for the first time after irradiation of a beryl crystal; the line gradually disappears on heating to 300°C.

Keywords: beryl, colour centre, electron spin resonance, gemstones, India, optical absorption

Introduction Technique Abbreviations em enhancement is a field of high potential wherein less attractive EPMA Electron Probe Micro Analysis Ggemstones are transformed to more EPR Electron Paramagnetic Resonance desirable stones by various methods such as ESR Electron Spin Resonance chemical treatment, irradiation and heating; e.g. rendering an attractive blue hue to a IVCT Intervalence Charge Transfer colourless topaz crystal by irradiation, and NIR Near InfraRed removal of patches of silk in ruby by intense OA Optical Absorption heating. An exhaustive review of such techniques is discussed by Nassau (1994). In RT Room Temperature the present paper the authors have UVCT Ultraviolet Charge Transfer documented colour enhancement

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 TableTable I:I: EPMA EPMA of of colourless colourless beryls beryls Experimental details \ w.Wt.%% 1 22 Experimental details

Colourless beryl samples from the SiOSi0, 2 -65.6965.6988 64*2464.2400 Colourless beryl samples from the Badmal mines of Orissa were »radiated ! AIAlPA3 17.7417.7400 17,4417.4422 usinBadmalg a minesCavity of Resonato Orissa werer typ irradiatede linear Electrousing an CavityBeam ResonatorAccelerato typer (modeLinearl ; FéFeOO 0540.5455 0.740.7444 KcfcïLUéElectron ) Beamat th eAccelerator Isotope Division(model, I MnMnOO 0.020.0255 0.010.0122 No. ILU6) at the Isotope Division, &AJKC Mtmbai India. An eneigy of Cr 0 0.020.0277 0.030.0311 1 Cr2A3 1.BARC,7 KfeV Mumbai,w$$ used Indiaand th. eAn bea energym curren oft V 0 0.032 0.012 wm1.7 MeV mairtfatae was usedd andat 2the m beamA wit currenth the ! V2A3 0.032 . 0,012 was maintained at 2 rnA with the Ti0 0.034 samples kept on a water-cooled TiOz 2 0.034 samples kept on a water-cooled '—' aluminium target The samples were NiO 0.022 0.016 aluminium target. The samples were ! NiO 0.022 0.016 also subjected to gamma-ray radiation also subjected to gamma-ray radiation CoO 0.056 0.056 Wmg a ^Q> source. | CoO 0.056 0i)56 using a 6DCO source. MgMgOO 0.090.0933 om0.281 OnthOn thee basebasess ooff externaexternall morphologmorphologyy CaCaOO 0.020.0200 0.040.0411 anandd aa conoscopiconoscopicc interferencinterferencee figurefigure,, ththee 0.019 samplesampless werweree cucutt paralleparallell (H||c(Hlle)) anandd KKpp 0.019 0.030.031Ï pm^m^âsœperpendicular (Hlc(H.Lc)) ttoo Ehthee c-axic-axiss anandd Na 0 0.206 0.275 ; hid ékmmom erf about 13 x 15x 10 Na220 0.206 0.275 had dimensions of about 1.5 x 1.5 x 10 mm F 0.216 0.057 forfor SSESRK measurementsmeasurements.. E>ESRR measuremeasure­- F 0,216 0.057 Total 84.733 menémentss werewen? carriedcarried outout onon a a Varian Varian E E-11-1122 Total 84.733 83;2383.2388 E4inE-linee centurcenturyy serieseriess X-banX-bandd ESESRR spectrometer which utfl&es 100 KHz 1.Whe1. Whenn irradiated irradiated,, colou colourr change changedd t too greenish-yellowgreenish-yellow.. spectrometer which utilizes 100 KHz 2.Whe2. Whenn irradiatedirradiated,, colou colourr change changedd t too yellow-orangeyellow-orange.. 239 field modulation. Tetra Gyno Nitro field modulation. Tetra Cyno Nitro NBNB:: TotaTotall iroironn reporte reportedd a ass FeOFeO;; BeBeOO anandd HHp20 nonott 209239174 Etfcyl&iEthylenee CK3NE(TCNE,, g~2.0Ö277g = 2.00277)) waswas useusedd determineddetermined.. aass a standarstandardd forfor g-g-factorf actor measurements. A Varian variable temperature accessory A Varian variable temperature accessory experimentexperimentss conducteconductedd oonn colourlescolourlesss berylberylss wawass useusedd ttoo carrcarryy outout experimentsexperiments atat different temperatures. frofromm BadmaBadmall mineminess ooff OrissOrissaa statestate,, IndiaIndia,, different temperatures. usinusingg aa radiatioradiationn techniquetechnique.. . PolarisePolarizedd OAsOAs werewere measuredmeasured atat BeryBeryll iiss aa typicatypicall cyclosilicatcyclosilicatee mineraminerall variablvariablee temperaturestemperatures overover 300-2500300-2500 nmnm witwithh ththee chemicachemicall formulformulaa BeBe3AlzSi60l8'Al Si 0 . IItt l1 3 2 6 18 <2S€XKMQ00cnr(25000-4000 cm- ) rangerange withwith a hahass aa honeycomb-likhoneycomb-likee hexagonahexagonall crystacrystall SchimadsSchimadzuu UVUV 3101PC3101PC scanningscanning structurstructuree belonginbelongingg ttoo ththee spacspacee grougroupp spectrophotometerspectrophotometer.. ColourlessColourless berylberyl P6/mccP6/mcc.. ThThee SiSiPl86018 sixfolsixfoldd ringringss ooff Si0Si044 crystalcrystalss cucutt alonalongg thethe acoc plane werewere tetrahedrtetrahedraa liliee ononee abovabovee ththee otheotherr alonalongg ththee doublydoubly polishedpolished toto a crystalcrystal thicknessthickness ofof CC66 axiaxiss anandd forformm intercommunicatinintercommunicatingg 1.01.0 mm.mm . PolarizedPolarized sheetssheets (HN(HN22 22) ) werewere channelchannelss (Figure(Figure la).laY. ThThee channelchannelss araree joinejoinedd useusedd toto obtainobtain polarizedpolarized spectra.spectra. HeatHeat lateralllaterallyy b byy Al AP+3+ anandd Be Be2z++ ion ionss (Figure(Figure lb).lb). ThThee treatmentstreatments inin airair atat temperaturestemperatures upup toto aluminiualuminiumm anandd berylliuberylliumm ion ionss araree locatelocatedd iinn 500500°°C werewere carriedcarried outout usingusing anan electricelectric distortedistortedd octahedraoctahedrall anandd tetrahedratetrahedrall sitesitess furnace, withwith samplessamples keptkept inin aa nickelnickel respectivelyrespectively,, whereawhereass ththee Si0Si044 tetrahedrotetrahedronn iiss crucible.. AnalysesAnalyses ofof cocolourleslourlesss berylberyl nearlnearlyy undistortedundistorted.. ThThee diametediameterr ooff ththee samplessamples werewere carriedcarried outout byby WDSWDS channelchannelss varievariess betweebetweenn 2. 2.88 ÂA i inn th thee planplanee o off EPMAEPMA usingusing anan SX-50SX-50 Microprobe.Microprobe. Si 0 rings and 5.1 A between neighbouring Si6601l88 rings and 5.1 A between neighbouring OperatingOperating conditionsconditions werewere 1515 kV kV ringringss anandd thetheyy araree capablcapablee ooff accommodatinaccommodatingg acceleratinacceleratingg voltage,voltage, 2020 nA nA beam beam current curren t aa numbenumberr ooff elementelementss (e.g(e.g.. NaNa,, KK,, RbRb,, CCss anandd andand 1010 ss countingcounting time;time ; thethe resultsresults areare Fe) and molecules (e.g. C0 and H 0). Two Fe) and molecules (e.g. CO22 and H220). Two givengiven inin Table 1. I. typetypess ooff wate waterr moleculemoleculess havhavee bee beenn recorderecordedd iinn beryberyll occupyinoccupyingg twtwoo distincdistinctt positionpositionss iinn

Maxixe-typeMaxixe-type colourcolour centre centre in naturalin natural colourless colourless beryl fromberyl Orissa, from India:Orissa,India: anan ESRESR and and OA OA investigation investigation Approx 5.1 A

Level of Si atoms in

Si6018 rings 1 1 1 1 1 Levels of Be and 1 Al atoms 1 1 1 0.< 1 0'. 1 ""-: 1 0'1 II 1 UI 1 1 1 1 1 1 o 1 1

0 oxygen 240 o6

Ap prox2.s A

Figure La: Schematic drawing parallel to c-axis showing the Fe3+ ion in a channel site in the beryl structure (modified after Wood andNassau, 1968).

the channel site (Wood and Nassau, 1967); centres which include trapped electrons the presence of such water molecules has and oxidized and reduced cations and also been noticed in the Orissan beryls anions. It has been found that on irradia­ (Mathew et al., 1997). tion, colourless beryl from various localities High energy radiations are capable of turns to (i) pale brown (Mukerjee, 1951); (ii) - changing the colour of several minerals and blue (N03 and CO/- impurity bearing of inducing a variety of radiation damage variety: Nassau et al., 1976); and (iii)

]. Gemm., 1998, 26, 4, 238- 251 209241

Figure lb: Structure of beryl projected on plane perpendicular to c-axis. yellow-orange (Nassau et al., 1976; yellow-green and yellow (Sinkankas and Sinkankas and Read, 1985). Nassau et al Read, 1985). Thus, the colour of iron- (1976) observed that if the original beryl is containing beryls depends on the yellow or green, then a green or blue-green distribution of iron in the channel, colour results from generation of a Maxixe octahedral Al site, tetrahedral Be site and colour centre. According to a few authors interstitial positions and upon the character (Wood and Nassau, 1968; Blak et al, 1982) of their interactions. From the above Fe2+ in a channel site is more powerful in references it is evident that several causing a blue colour than in the researchers have proposed different views substitutional Be and Al site, where it fails to explain the cause of colour in beryl. In to induce any effect on colour. They attrib­ the present study, it is shown that on uted yellow in beryl to Fe3+ in a substitu­ irradiation some colourless beryl tional site, whereas its presence in the (goshenite) samples have turned to green to structural channel has no effect on colour. greenish-yellow and some to yellow-orange However, according to Goldman et al. (Table I). The green colour fades on heating (1978), the blue colour is due to IVCT and to 300°C, leaving yellow, and finally 3+ yellow is due to UVCT arising from Fe in becomes colourless on further heating to 2+ 3+ a channel site. When both Fe and Fe ions 500°C. The yellow-orange beryl also turns are present, the resultant colour depends on colourless at 500°C. In this study, we report the proportion of each, thus explaining the the results of the investigation on 'gamut of hues' that may be observed from colourless beryl using the techniques of blue to various shades of blue-green, ESR and OA.

Maxixe-type colour centre in natural colourless beryl from Orissa, India: an ESR and OA investigation b :/ g = 2.00277

I I

a a Hlle

H.Le

209242174

1000 2000 3000 4000 5000 MAGNETIC FIELD (Gauss)

Figure 2: ESR spectra of colourless beryl (before irradiation)irradiation) forfor twotwo magneticmagnetic fieldfield directionsdirections (HI(H\\c Ic and H.l..c)H±c) in the 3200 G region. The g = 2.002772.00277 lineline shownshown inin thethe figurefigure isis thethe markermarker (TCNE)(TCNE)..

ResultsResults andand discussiondiscussion TheThe ESRESR spectrumspectrum ofof unirradiatedunirradiated colour­colour­ lessless berylberyl presentlypresently underunder studystudy isis shownshown iinn Electron Spin Spin Resonance Resonance (ESR) (ESR) studies studies on on Figure 2 2 for fo rthe the two two field field directions directions (Hllc (H|| cand and unirradiated beryl beryl Hl.c).Hlc). SimilarSimilar spectraspectra werewere reportedreported byby DavirDavir ESR,ESR, alsoalso referredreferred toto asas EPR,EPR, isis aa spectro­spectro­ andand LowLow (1960)(1960) andand BlakBlak etet al. (1982).(1982). ThThee scopicscopic techniquetechnique basedbased uponupon resonantresonant spectrumspectrum consistsconsists ofof aa largelarge asymmetricalasymmetrical absorptionabsorption ofof microwavesmicrowaves byby paramagneticparamagnetic singlesingle lineline (labelled(labelled 'b')V) nearnear thethe freefree electronelectron 3+ substancessubstances tunedtuned byby anan externalexternal magneticmagnetic resonanceresonance attributedattributed toto Fe3+ inin thethe channelchannel field.field. ItIt isis aa powerfulpowerful techniquetechnique inin detectingdetecting sitesite (g(g == 1.9961.996 forfor HH parallelparallel andand gg == 1.9981.998 forfor colourcolour centrescentres whichwhich areare responsibleresponsible forfor HH perpendicularperpendicular toto thethe crystallographiccrystallographic c-c­ 3+ colourcolour inin minerals.minerals. TheThe firstfirst detaileddetailed ESESRR axis).axis). TheThe observedobserved g-valueg-value forfor thethe FeFe3+ ionion studies on beryls were carried out by Davir (strong(strong line)line) isis closeclose toto thethe freefree electronelectron valuevalue studies on beryls were carried out by Davir 3+ andand LowLow (1960),(1960) , inin which which theythey proposedproposed thatthat ofof 2.002332.00233.. TheThe FeFe3+ inin thethe channelchannel isis Fe33++ ions occupy octahedral AP+3+ sites and surroundedsurrounded byby 2424 oxygenoxygen atoms.atoms. TheThe Fe ions occupy octahedral Al sites and 3+ alsoalso indicatedindicated theirtheir probabilityprobability inin tetrahedraltetrahedral distancedistance betweenbetween FeFe3+ andand anan oxygenoxygen atomatom isis 3.4 Â in the Si0 plane and 4.1 Â in the plane sites.sites. 3.4 A in the Si066 plane and 4.1 A in the plane

J./ . Gemm.,Gemm., 1998,1998, 26,26,4, 4, 238-251238-251 g = 4.32 g = 2.00277 I I I I 1 Fe3+ 1 1 a b 1 I 1 I I Fe3+ "T~

1000 2000 3000 4000 5000 MAGNETIC FIELD (gauss)

Figure 3a: Variable temperature ESR spectra of colourless beryl (after irradiation) for the magnetic 243 field parallel (HIIe) to thecrystallographic c-axis depicting the presence ofnewlineat 1500 G.

of 0 6 (Blak et al., 1983) and these distances field along the c-axis and for a random are too large to allow the occurrence of any orientation in the plane perpendicular to the significant crystal field splitting in the ESR c-axis respectively. In addition to the main spectra and consequently in ESR absorption. Fe3+ peak at 3200 gauss, an additional line is Therefore, Fe3+ with a 'g' value close to observed in the low field region around 2.00233 behaves almost as a free ion; thus it 1500 G. Although such lines were reported probably occupies a site in the structural by Blak et al. (1982) in natural green beryl, channel (Blak et al., 1983). Additional weak they are observed here for the first time in lines (labelled 'a') are observed on either side natural beryl crystals after irradiation. The of the strong line. These weak lines are g-factors in the vicinity of 4.3 in many possibly due to the small presence of Fe3+ minerals (e.g. feldspars and mica) have been substituting in the octahedral AP+ site as attributed to high spin Fe3+ in a low suggested by Davir and Low (1960). symmetry environment of rhombic distorted site (Castner et al., 1960; Abragam and Bleany, 1970; Calas, 1988). Therefore it is ESRstudies on irradiated beryl likely that in the beryl sample under study, 3+ The colourless beryl samples from Orissa the Fe ion occupies a distorted rhombic site. 3+ as explained above turned to greenish­ This indicates that the above Fe ion was 2+ yellow and some to yellow-orange after initially in the form of Fe in the irradiation in the electron beam, whereas unirradiated sample and on subsequent 3+. gamma radiation did not produce any colour irradiation it was oxidized/ionized to Fe change. Figures 3a and 3b show the ESR The low-intensity line observed around spectra of irradiated beryl for the magnetic 1500 gauss in the ESR spectrum (Figures 3a

Maxixe-type colour centre in natural colourless beryl from Orissa, India: an ESRandOA investigation g = 4.30 g = 2.00277 I I I Rr~H' ____----- RT lOOT ------/ A~ 150 0C~ _----- 100°C 200 0 C~ __---- 150°C 250 ° C~ _----- 200°C I _---- 250°C

_~---- 300°C

1000 1500 2000

I I 2975 3000 3470 5000 MAGNETIC FIELD (Gauss) 209244 Figure 3b: 3b: VariableVariable temperature temperature ESR ESR spectra spectra of colourless of colourless beryl (afterberyl irradiation)(after irradiation) for the magnetic for the magnetic fieldfield perpendicularperpendicular (Hl.c) (Hlc) to tothe the crystallographic crystallographic c-axis. c-axis.

3+ and 3b)3b) is is tentatively tentatively assigned assigned here here to to the the Fe Fe3+ hue.hue. ThThee yelloyelloww anandd yellow-orangeyellow-orange colourscolours ionion formeformedd bbyy oxidatiooxidationn ooff Fe2+ atat thethe Be2+ araree foundfound ttoo disappeadisappearr arounaroundd 500500°°CC inin bothboth tetrahedratetrahedrall site.site. AsAs thethe Fe2Fe2++ ionion isis characterized characterized berylberylss irradiateirradiatedd ttoo greenish-yellowgreenish-yellow andand bbyy a shortshort spinspin relaxationrelaxation time,time, itit wawass notnot yellow-orangyellow-orangee respectively.respectively. possiblpossiblee toto observeobserve thethe ESRESR lineslines attributableattributable A ''gg'' valuevalue ofof 4.4.33 isis notnot expectedexpected fromfrom anan 2+ 3+ toto Fe + inin thethe presentpresent ESRESR investigationinvestigation atat Fe3+ ionion situatedsituated atat ththee channelchannel site,site, sincesince roomroom temperature.temperature. here ththee ionion behavesbehaves almostalmost asas a freefree electronelectron TheThe ESESRR lineslines aroundaround thethe g-factorg-factor ofof 4.34.3 (g(g = 2.2.00233)00233).. ItsIts possiblepossible substitutionsubstitution atat anan 3+ (Figures 3a 3a and and 3b) 3b) due du toe theto th Fee 3Fe+ ion io shown sho aw a octahedoctahedrarall sitesite isis alsoalso doubtful,doubtful, asas itit isis clearlyclearly gradualgradual decreasedecrease inin intensityintensity onon heating,heating, seenseen inin thethe ESRESR spectrumspectrum thatthat thethe 4.34.3 signalsignal 3+ 2+ 3+ whichwhich pointpointss toto a reductionreduction ofof Fe3+ toto Fe2+.. ofof Fe3+ disappearsdisappears atat 300°C300°C andand yet thethe 3+ TheThe Fe3+ lineline disappearsdisappears aroundaround 300°C300°C andand isis samplesample retainsretains itsits yellowyellow colour.colour. ItIt isis wellwell accompaniedaccompanied byby a changechange inin colo~rcolour ooff documenteddocumented byby manymany authorsauthors (e.g. WooWoodd irradiatedirradiated berylberyl fromfrom greenish-yellowr toto andand Nassau,Nassau, 1968)1968) thatthat yellowyellow inin berylberyl isis duedue 3+ yellow.yellow. ThisThis observationobservation appatentlyapparently toto thethe presencepresence ofof Fe3+ atat anan octahedraloctahedral site.site. 3+ indicatesindicates a possiblepossible correlationcorrelation ofof Fe3+ atat thethe FurtherFurther itit isis knownknown thatthat thethe bondbond distancesdistances tetrahedraltetrahedral sitesite toto thethe colorationcoloration inin irradiatedirradiated forfor Be-OBe-O andand Si-OSi-O areare 1.6571.657 andand 1.6081.608 AÂ beryl.beryl. However,However, itit isis importantimportant toto mentionmention respectivelyrespectively andand thethe typicaltypical Fe-OFe-O bondbond 3+ herehere thatthat thethe disappearancedisappearance ofof thethe aboveabove Fe3+ distancedistance isis 1.9801.980 AÂ (Hazen(Hazen et al.,al, 1986; ESRESR signalsignal aroundaround 300°C300°C isis alsoalso observedobserved inin ShannonShannon andand Prewitt, 1969).1969). ItIt isis thereforetherefore 2+ irradiatedirradiated yellow-orangeyellow-orange beryl;beryl; butbut therethere isis likelylikely thatthat Fe2+,Fe , althoughalthough characterizedcharacterized byby nono significantsignificant changechange inin thethe yellow-orangeyellow-orange largelarge ionicionic radius,radius, substitutessubstitutes inin smallsmall

].J. Gemm.Gemm.,, 19981998,, 2626,, 4,4, 238-238-251251 quantities at the fourfold coordinated OA studies of irradiated coloured beryl beryllium site, while most Fe2+ ions prefer were carried out at various temperatures. the octahedral Al3+ site and the channel site. The absorption spectra of irradiated According to Samoilovich et al. (1971), on greenish-yellow beryl taken at RT are shown thermal excitation (heating) of the electron, in Figures 4a and 5. UVCT is due to electron the capture cross-section is greater for the transfer from anion to cation, i.e. transfer of 3+ 3+ 2- 3+ [Fe ]tetr than for the [Fe ]oct ion. In the electron from O ligands to a central (Fe ) present study, step annealing experiments metal ion (Rossman, 1988) and the 3+ 2+ show that [Fe ]tetr is first reduced to [Fe ]tetr absorption this causes below 390 nm extends below 300°C (Figures 3a and 3b). On the other into the visible region. These transitions 3+ 2+ hand, [Fe ]oct is found to reduce to [Fe ]oct occur in the ultraviolet region and produce at higher temperatures. These findings are in absorption 2 to 3 orders of magnitude higher accordance with the expectations of than the ordinary crystal field transition Samoilovich et al. (1971). It was found that (Marfunin, 1979). The tail of the absorption the greenish-yellow colour as well as ESR band extends into the visible region due to an signals could be restored after repeated increase in concentration of Fe3+, which in turn irradiation. resulted from ionization of Fe24 as seen in ESR spectral studies also revealed that, on Figures 4a and 5. The strongest absorption is in irradiation with an electron beam, beryl the violet and the tail extends into the green. produces atomic hydrogen (H°) represented The visible region of the optical spectrum by two weak satellites at 2970 and 3470 gauss in the irradiated greenish-yellow beryl is (Figures 3a and 3b). The atomic hydrogen characterized, in the ordinary ray only (o-ray occupies the channel site and appears to be or ±c), by sharp absorptions at 644 and 688 formed by irradiation-induced splitting of nm (Figure 4b). Such a sharp absorption the hydroxyl group (Koryagin et al, 1966). In pattern is not seen in the beryl irradiated to the present study it was observed that H° yellow-orange. The sharp absorption feature 209245 becomes unstable above 200°C. Similar weak observed above is similar to the optical H° satellite peaks are also observed in spectrum of Maxixe-type beryl observed by samples irradiated by gamma rays, and these Nassau et al. (1976) who attributed this also disappeared above 200°C. absorbance to colour centre formation and ESR experiments were also carried out on concluded that this was the cause of blue greenish beryl at low temperatures (77 K) to colour in Maxixe-type blue beryls from observe the presence of colour centres in the Brazil. Later workers (Edgar and Vance, beryl lattice, but failed to reveal the possible 1977; Andersson, 1979) with the help of ESR presence of the ESR lines attributable to studies, inferred this centre to be the C03~ colour centres due to strong overlap from the radical in Maxixe-type beryl and N03 in 3+ Maxixe beryl. These radicals are derived Fe signal around the free electron 2_ resonance region. Nevertheless, the presence from C03 and N03" respectively residing in of such colour centres has been deduced the structural channel sites of beryl crystals. from OA spectroscopy as explained in the On irradiation, these ions lose an electron next section. and become C03~ and N03 radicals. This results in generation of a hole centre in Maxixe-type beryls. Nassau et al. (1976) Optical Absorption (OA) studies defined Maxixe beryls as those natural deep In general three types of processes blue beryls formed by natural radiation in generally contribute to OA spectra in which the impurity precursor is N03", minerals (Rossman, 1988): whereas Maxixe-type beryls are those deep blue-green beryls produced by artificial 1.crystal field; irradiation having the impurity precursor as 2 2.charge transfer (UVCT and IVCT); C03 ~. Edgar and Vance (1977) considered 3.absorption edge. also the presence of HC03" precursors to be

Maxixe-type colour centre in natural colourless beryl from Orissa, India: an ESR and OA investigation W AVENUMBER (cm-' )

20,000 10,000 7,000 5,000 4,000

Fe> in channel site

J HzO __ I, I I I I ~ u I, Z I

!/ \', I r j f \ I \, r.I l ,- y ! , 1; \\ Ii I '" .• I ... I \ ,

I '" I ... \ ... \ '\ /:' ,//J\\/<:J " '' .{ . 1 \ •• .. 1\ ' \ J I " I, J \, ... I -, 1 -, '\ 1 .... , -, I

- - I

300 500 1,000 1,500 2,000 2,500 WA VELEN GTH (nm)

Figure 4a: Absorption spectra (UV-VIS-NIR) of irradiated greenish-yellow beryl showing the Fe2+ peak in channel sitepolarized along a-ray. Crystal thickness = 1.0mm. Solid line RT,dashed line 300°C anddotted line 500°C.

J. Gemm., 1998, 26, 4, 238-251 I I I I I N ~ 00 I -0 -0 1 I I I I I ~ ~ ~ I I I I I

I I I I I I I \ I \ \ Maxixe \ \ blue \ colour centre \ (Nassau et al., 1976) \ \ \ ~ \ U \ 247 Z \ -c \ I:Q \ ~ \ \ ~ \ I:Q \ \ < \ \ \ , \ " '" \ ", \ ~ ~ ' ,. . -. , ~ " .....,~ ' \ '1', I ' " / \ ' / \ / , / , / , / , / v ., ..... - ..... // / , .... __.....

300 550 800

WAVELENGTH (nrn)

Figure 4b: A bsorption spectra (UV-VIS) of irradiated greenish-yellow beryl polarized along o-ray showingthepresence ofMaxixe-typecolour centre. Solid lineRT, dashed line300°Cand dotted line500°C.

Maxixe-type cotour centre in natural colourless berylfrom Orissa, India:an ESR andOA investigation WAVENUMBER (em") 20,000 10,000 7,000 5,000 4,000

I 1 I 1 1 1 I 1 I: I: I : I : rver 1 : I : 1 : 1 ~ \ 1 : 1 I I : I : I: \ : \ ~ // -, , I I

\ \ ...... /;/ '"""'"\ ~ 1/~ ...... \ JfI,: •• \ ...... / .,-' -',. ', r , ~ -< ...' '-. 'I '1\ i /">...... ' I / :'\,: .. " '---, / ~~ ...... I' / :.', ,_• •/••'.,...... ,' _ _ ...... -:.~ .~, /•••: . ---:-:'. .: " "'':: ,,": .-= .-:::. ,

300 500 1000 1500 2000 2500

248 WAVELENGTH (n m)

Figure5: Absorption spectra (UV-VIS-NIR) of irradiated greenish-yellow beryl showing the Fe2+ peak in octahedral Al sitealong e-ray. Crystal thickness = 1.0 mm. Solid lineRT, dotted line300°Cand dashed line500°C.

more reasonable than CO/- due to the 1000nm polarized Ilc (parallel to the crystallo­ formation of a neutral hydrogen atom (HO) graphic c-axis) was attributed to Fe2+ in the after irradiation. In the present study, as channel site and the band centred at 620 nm explained earlier, the formation of atomic (1Ic) was attributed to Fe2+ in a different site. hydrogen is seen both in the case of electron Samoilovich et al. (1971) and Parkin et al. beam and gamma-ray irradiation. However, (1977) agreed with the assignments of Wood no colour is produced from gamma-ray irra­ and Nassau (1968). However, according to diation and this indicates that atomic Price et al. (1976), bands at 810 and 1000nm hydrogen produced from irradiation comes (1Ic) arose from Fe2+ in the AP+ site and the solely from Hp. 810nm band (Lc) possibly indicated Fe2+ at a The existence of two distinct types of Fe2+ tetrahedral site. Goldman et al. (1978) in colourless Orissan beryl is indicated by the attributed 820 nm and 970nm peaks in the optical spectra (Figures 4a and 5). Wood and spectrum polarized to Fe2+ in the AP+site and Nassau (1968) recognized three absorption assigned 820 nm (Lc) and 2100nm (lie) peaks bands in the NIR region and attributed them to Fe2+ in a channel site. They ascribed a broad to Fe2+. A band near 810 nm polarized .lc absorption feature seen from 1700 nm to (perpendicular to the crystallographic r-axis) 2500nm also to iron in a channel site. Thus was assigned to Fe2+ in the AP+ site. On the there is no universally agreed point of view other hand, a set of bands near 810 nm and regarding the interpretation of OA spectra of

J. Gemm., 1998,26,4,238-251 beryl. Panjikar (1995) also carried out 2.the intensity of the 820 nm band (o-ray) extensive work on Orissan beryls and decreased; 2+ indicated the possible presence of Fe bands 3.the intensities of the 760 and 920 nm from octahedral as well as tetrahedral sites. bands (e-ray) decreased; and In the present study, strong absorption 4.the absorption band at 684 nm (e-ray) 2+ due to the crystal field transition of Fe at disappeared. 820 nm (Figure 4a) polarized along the ordinary ray (1c) is assigned to Fe2+ in the On further heating to 500°C, it was channel site. Since the octahedral Al site is observed that: distorted, the Fe2+ absorption band is 5.the intensity of the 820 nm band (o-ray) expected to be in pairs rather than a single increased; band due either to distortion of the 6.the intensities of the 760 and 920 nm polyhedron or to the dynamic Jahn-Teller bands (e-ray) increased; and effect (Goldman et al, 1978; Burns, 1970). This absorption pair feature is seen at 760 7.the UVCT tail receded to shorter wave­ and 920 nm polarized along the extra­ lengths and became steeper. ordinary ray (||c) (Figure 5). It is attributed to The first observation indicates that the the spin allowed crystal field transition of sharp absorption features at 644 and 688 nm 2+ 5 5 5 Fe ( T2 -> E, D), assigned to arise from have thermal decay characteristics, which are Fe2+ in the octahedral site. This is further similar to the observation of Serway (1967) supported by the barycentre energy of on irradiated calcite. In irradiated calcite, the 12,150 cm-1, which indicates that the Fe2+ is 650 nm band shows thermal decay situated in a site of 1.94 Â average metal behaviour similar to that of the ESR signal oxygen distance (Faye, 1972). This agrees attributed to the C03" molecular ion. favourably with the 1.90 Â distance Identical decay characteristics of a narrow determined for the octahedral Al site in beryl absorption band were also observed by 209249 by Gibbs et al (1968). Although the presence Nassau et al. (1976) in Maxixe-type blue and of Fe3+ at the tetrahedral site cannot be green beryls as shown in Figure 4b. It appears deduced with any confidence from the OA that a defect centre, similar to Maxixe type, spectrum, an absorption close to 684 nm probably results in the blue coloration in (e-ray) is present as a shoulder after irradiated Indian colourless beryl. On irradiation (Figure 5). This can be attributed heating to 300°C, the defect centre decays to IVCT between Fe2+ and Fe3+, the Fe2+ at an and the crystal becomes yellow. octahedral or channel site and the Fe3+ at a The second and third observations tetrahedral site. indicate that the amount of Fe2+ ions residing in the channel as well as in the octahedral site Heating experiments (in air) decrease. These changes are due to the fact that, on annealing, the Fe2+ ions in both As described earlier, after heating the channel and octahedral sites are converted irradiated beryl to 300°C, the greenish- into Fe3+ ions. This explains the decrease in yellow beryl turned yellow and no the 820 nm (o-ray), 760 and 920 nm (e-ray) significant change in hue of yellow-orange bands. The above observation indicates that beryl was observed. On further heating to on irradiation there is partial reduction of 500°C both greenish-yellow and yellow- 3+ 2+ Fe to Fe . A similar feature was also orange beryl become colourless. The observed by Goldman et al. (1978) in a following changes in the optical spectrum natural yellow beryl which, on irradiation were seen after heating the beryl crystals to and subsequent heating to 500°C, showed 300°C (Figures 4a and 5): recovery of the Fe2+ ion in the channel as well 1. sharp absorption peaks at 644 and as in the octahedral sites. The complete 688 nm, which are polarized only along disappearance of IVCT at 684 nm in the the ordinary ray, disappeared; fourth observation is in accordance with the

Maxixe-type colour centre in natural colourless beryl from Orissa, India: an ESR and OA investigation disappearance of the Fe3+ ESR line at The combination of these two colours 1500 gauss at 300°C Thus, in addition to the results in a greenish-yellow hue in the beryl blue coloration due to a Maxixe centre, the crystal. In the yellow-orange irradiated IVCT band at 684 nm possibly also contributes beryl, the above defect centre does not form to the blue colour after irradiation of colourless due to the absence of suitable precursors beryl. However, in the yellow-orange beryl the except for the oxidation of Fe2+ at the Al site g-value of 4.3 in the ESR spectrum is seen only and the associated UVCT tail which results as a small hump, unlike sharp peaks in irradi­ in a yellow colour. 2+ ated green beryl. This indicates that the Fe is On heating, the defect centre and IVCT present only in very small concentration at the decays at 300°C, resulting in disappearance of tetrahedral site in yellow-orange beryl, which the blue colour. On subsequent heating to does not favour appreciable charge transfer to higher temperature, there is formation of some be observed in the optical spectra. The fifth Fe2+ and an associated retreat of the UVCT tail observation indicates that the amount of Fe2* 3+ to shorter wavelengths. This results in colour­ ions has increased. This suggests that the Fe 3+ 2 less beryl at 500°C. Although the Fe line at ions residing in the channel are reduced to Fe * 1500 gauss attributed to the tetrahedral site is by the thermal release of electrons. The sixth tentative, its appearance after irradiation and observation indicates that on heating above 2+ disappearance after heating clearly demon­ 300°C, the Fe ion (760 and 920 nm, e-ray) strates the oxidation and reduction increases in concentration at octahedral Al phenomena. It is quite possible that various sites due to partial reduction of the Fe3+ ion to 2+ shades of green and yellowish-orange beryl Fe . The fifth and sixth observations are may have formed in nature from colourless accompanied by the seventh observation. This 3+ beryl due to natural irradiation during the is consistent with the decrease in Fe concen­ course of geological time and subsequent tration accompanied by a recession of the 3+ 2 heating of the host body might have resulted 250209 Fe - O " charge transfer band towards the in the development of various shades of green. ultraviolet region. These changes are accompa­ The differential behaviour of colourless beryl nied by a change in colour of the sample from to irradiation from the same locality calls for yellow to colourless. It is observed that the further studies on the genesis of beryl crystals major portion of increase in intensity of the in relation to their crystal chemistry. 820 nm band (o-ray) and the 760 and 920 nm bands (e-ray) manifests mainly above 300°C, and the UVCT tail recession also starts above Acknowledgements 300°C. Therefore it would not be appropriate to correlate the yellow colour formed after The authors are grateful to Dr S.M. Rao, irradiation to the UVCT tail arising from Fe3+ Shri. A.B. Majali, Ashok Kalurkar, K.S.S. in the channel site. Sarma and Abdul Khadir, Isotope Division, BARC, for irradiation of samples. Sincere thanks are also due to Dr Amitav Das and Conclusion Ms Beena Narayanan, CSMCRI, Bhavnagar, for helping in optical absorption. We are very From the present ESR and OA study of grateful to Dr B. Basavalingu, Mysore irradiated coloured beryls it appears that the University, for carrying out EPMA analysis. coloration with electron-beam irradiation of One of the authors (GM) would like to thank colourless beryl to green to greenish-yellow his colleagues M.A. Mamtani and and decoloration of the blue component and A.S. Khadkikar for useful discussion. We also yellow with heating is due to the following: thank Professor A.B. Vassilikou-Dova, 1.formation of a defect centre and possible University of Athens, Greece, for critically IVCT giving rise to the blue colour; reviewing an earlier version of the paper. 2.radiation-induced oxidation of Fe2+ and Financial support provided to RVK by the associated UVCT tail, which results in BRNS-DAE, India (35/4/94-R&D II) is a yellow colour. gratefully acknowledged.

J. Gemm., 1998,26,4,238-251 ReferenceReferencess KoryaginKoryagin,, V.E,V.F., andand GrechushnikovGrechushnikov,, B.N.B.N.,, 1966.1966. EPEPRR ooff atomicatomic hydrogenhydrogen iinn berylliumberyllium.. Sov. Phys. Sol. State, 7,7, AbragamAbragam,, A,A., andand Bleany,Bleany, B.,B., 1970.1970. Electron paramagnetic 2000-122000-12 resonance of transition metal ions. OxforOxfordd UniversityUniversity Marfunin, A.S., AS., 1979. 1979. Physics Physics of of minerals minerals and and inorganic inorganic materials. mate­ PressPress,, LondonLondon rials. Springer-Verlag,Springer-Verlag, BerlinBerlin.. 207-54207-54 Andersson,Andersson, L.O.L.O.,, 1979.1979. TheThe differencedifference betweebetweenn MaxixeMaxixe Mathew, G., G., Karanth, Karanth, R.V., GunduR.V., Rao,Gundu T.K., Rao, and T.K, and beryl and and Maxixe-type Maxixe-type beryl: beryl: an electron an electron paramagnetic paramag­ Deshpande,Deshpande, R.S.RS.,, 1997.1997. ChanneChannell constituentconstituentss ofof alkalialkali resonancenetic resonanceinvestigation. investigation. J.Gemm., XVI J.Gemm.,(5), 313-17 XVI(5), 313-17 poopoorr OrissaOrissann berylsberyls:: aann FT-IFT -IRR spectroscopicspectroscopic study.study. BlakBlak,, A.R.AR,, Sadao,Sadao, IsotaniIsotani,, anandd Shigueo,Shigueo, WatanabeWatanabe,, 19821982.. Current Science, 7373,, 1004-111004-11 OpticaOpticall absorptioabsorptionn andand electroelectronn spinspin resonancresonancee ooff Mukerjee,Mukerjee, B.B.,, 1951.1951. ColouColourr ofof berylberyl.. Nature, 167,167, 602602 blubluee anandd greengreen berylberyl.. Phys. Chern.Chem. Mineral,Mineral, 88,, 161-6161-6 NassauNassau,, K.K,, 1994.1994. Gemstone enhancement. (2nd(2nd edn.)edn.) BlakBlak,, AR,A.R., Sadao,Sadao, Isotani,Isotani, andand Shigueo,Shigueo, WatanabeWatanabe,, 19831983.. 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DavirDavir,, M.M.,, anandd LowLow,, W.W.,, 1960.1960. ParamagnetiParamagneticc resonancresonancee andand Colloq. C6.C6. Suppl.Suppl. 12,37,811-1712, 37, 811-17 opticaopticall spectrumspectrum ooff iroironn iinn berylberyl.. Phys. Rev., 119,119, 1587-911587-91 RossmanRossman,, G.R.G.R.,, 1988.1988. OpticaOpticall spectroscopy.spectroscopy. In:In: Edgar,Edgar, A,A., andand Vance,Vance, E.R.,E.R., 1977.1977. ElectronElectron paramagneticparamagnetic Hawthorne,Hawthorne, F.C.EC (Ed.)(Ed.),, Reviews in mineralogy, Vol.Vol. 18. resonance,resonance, opticaloptical absorptionabsorption anandd magnetimagneticc circularcircular Spectroscopic methods in mineralogy and geology. dichroisdichroismm studiesstudies ofof ththee C033- molecular-ionmolecular-ion inin MineralogicaMineralogicall SocietySociety ofof AmericaAmerica,, 207-54207-54 irradiatedirradiated naturanaturall berylberyl.. Phys. Chem. 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Phys., 4646,, 1949-521949-52 StructuralStructural refinementrefinement ofof hydrouhydrouss andand anhydrousanhydrous Shannon,Shannon, R.D.R.D.,, anandd PrewittPrewitt,, CT.,C.T., 1969.1969. EffectivEffectivee ionicionic syntheticsynthetic berylberyl.. AI,(BeAl2(Be3Si6)O)01818 andand emeraldemerald radiradiii iinn oxideoxidess andand fluorides.fluorides. Acta. Cryst., B25,B25, 925-46925-46 AlAI1.9CrO.l(Be3Si6)018'1.9Cr0.1(Be3Si6)O18. Lithos, 1,1, 275--85275-85 Sinkankas,Sinkankas, J.,J., andand ReadRead,, P.G.P.G.,, 1985.1985. BerylBeryl. ButterworthsButterworths GoldmanGoldman,, 0.5.,D.S., RossmanRossman,, G.R.G.R.,, anandd Parkin,Parkin, KM.,K.M., 1978.1978. GeGemm Books,Books, LondonLondon.. 222255 pppp ChannelChannel constituentsconstituents ooff berylberyl.. Phys. Chem. Mineral,Mineral., 33,, WoodWood,, D.L.D.L.,, andand NassauNassau,, K.,K., 1967.1967. InfraredInfrared spectraspectra ooff 225-3225-355 foreignforeign moleculemoleculess inin berylberyl.. J.Chem. Phys. 4747,2220-8, 2220-8 Hazen,Hazen, R.M.RM.,, AuAu,, A.V.AV.,, andand Finger,Finger, L.W.,L.W., 1986.1986. HighHigh WoodWood,, D.L.,D.L., anandd NassauNassau,, K.K,, 1968.1968. TheThe characterisatiocharacterisationn ooff pressurpressuree crystacrystall chemistrychemistry ooff beryberyll (Be(Be3AI2Si6018)3Al2Si6O18) andand beryberyll anandd emeraldemerald bbyy visiblvisiblee anandd infraredinfrared absorptionabsorption euclaseuc1asee (BeAlSiO(BeAISiOpH).4OH). Am. Mineral,Mineral., 7171,, 977--84977-84 spectroscopyspectroscopy.. Am. Mineral., 5353,, 777--800777-800

Gemmologists' Compendium (7th edn) '16.99 by R. Webster, revised by E. Alan Jobbins Amber - the Natural Time Capsule '7.95 by Andrew Ross Prices quoted exclude postage and packing Gemmological Instruments Limited, 27 Greville Street, London Eel N 8TN. Tel: 0171-404 3334 Fax: 0171-404 8843

Maxixe-type colour centre in natural colourless beryl from Orissa, India:India: an ESR andand OA investigationinvestigation The chemical signature of emeralds from the Campos Verdes-Santa Terezinha Mining District, Goiás, Brazil G.M. Pulz1, L.J.H. D'el-Rey Silva2, L.S. Barros Neto3, T.M.M. Brum1, P.L.Juchem 1, C.A. Santos4, V.P.Pereira 1 and J.J. Silva1 1. Universidade Federal do Rio Grande do Sul-UFRGS, Instituto de Geociências, Centro de Estudos em Petrologia e Geoquímica, Laboratório de Gemologia, Porto Alegre, RS, Brazil. 91509-900 2. Universidade de Brasília-UnB, Instituto de Geociências, Brasília, DF, Brazil. 70910-900 3. Mineração Peneri, BR153, Km 8,5, Zona Industrial, Goiânia, GO, Brazil. 74001-970 4. Universidade Federal do Rio Grande do Sul - UFRGS, Instituto de Física, Laboratório de Espectroscopia de Mössbauer, Porto Alegre, RS, Brazil 91509-900

252 ABSTRACT: Emerald crystals from the Campos Verdes mining district have been analysed by inductively coupled plasma mass spectrometry 174 (ICP-MS), Fourier transform infrared spectroscopy and Mössbauer 2+ 3+ 209 spectroscopy. These gems contain measurable amounts of Fe , Fe , Cr, V, Sc, Ni and Zn; large-ion lithophile element (LILE, Ba, Sr, Rb, Pb) and high field strength element (HFSE, Zr, Y, Ti) contents are near or below the limit of detection. This chemical signature reflects the metasomatic reactions between the mineralizing fluids and the ultrabasic host-rocks of this gem deposit.

Keywords: Brazil, emerald, chemistry, infrared spectroscopy, Mössbauer spectroscopy

Introduction required heavy investment, extraction is The Santa Terezinha de Goiâs-Campos mostly performed by three large companies. Verdes region, herein termed the Campos Emerald is a variety of beryl (Be3Al2Si6018), Verdes mining district, located about 400 km characterized by different shades of green northwest of the capital Brasilia, Brazil, is (Bosshart, 1991). Beryl is a cyclosilicate in one of the most important Brazilian emerald which the arrangement of Si6018 rings production areas (Giuliani et al., 1990). contains channels parallel to the c-axis, Mining started on the surface and at shallow which can accommodate alkalis and mole­ depths on a small scale in the early 1980s. cules (such as H20 and C02), retained in the Currently, as the underground mines reach structure during crystallization (Aines and depths of more than 100 m and have Rossman, 1984; Wood and Nassau, 1968).

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355^565 2 • Chlorite-Talc schists . ~ B 1:: @ D Muscovite quartzites I -y ~g. Thrus ts F ntiform F Synform ~ ~ Magnetite-Muscovite schists 2A 2

" D Amphibole gneiss, ] amphibolites ::: <

~ 253 14° 20' 30" S

Figure 1: Simplified geological map of the Campos Verdes Mining District, Goitis. The rectangle represents the area occupied by the town of Campos Verdes, built right above the orebodies. AB is the linefor the simplified geological cross-section.

More recent metallogenic studies have Figure 2: Carbonate vein sample showing an demonstrated the importance of these emerald crystal from Campos Verdes. The length channels, as they provide clues for the of the crystal is about 25 mm. geochemical composition of fluids entrapped therein (Fallick and Barros, 1987). Since 1996, the Campos Verdes mining district has been the focus of intense geochemical research for gemmological objectives. This paper reports the results of the compositional determination of the emerald crystals by inductively coupled • plasma mass spectrometry, Mossbauer • spectroscopy and infrared spectroscopy, and the data provide diagnostic information.

Geological setting The Campos Verdes mining district lies within a relatively narrow, NNE-SSW

Thechemical signature ofemeralds from theCampos Verdes-Santa Terezinha Mining District, Goids, Brazil trending belt of the Santa Terezinha volcano- around 15° towards 350°. As a result, the sedimentary sequence which has been orebodies consist largely of cigar-shaped deposited on biotite and amphibole gneisses bodies of carbonate-talc schists enclosed in of probable Archean age (Ribeiro Filho, 1981; the core of the sheath folds. On a regional Souza and Leäo Neto, 1984). This volcano- scale it is part of a synformal structure. The sedimentary belt consists of talc schist, strong structural control of the orebody chlorite-muscovite-quartz schist, magnetite- demonstrates that the shear zones muscovite schist, muscovite quartzite and channelled the emerald-forming fluids. emerald-bearing biotite schist and chlorite- According to Barros and Kinnaird (1987a) carbonate-talc schist (Figure 1). The emerald the emerald-forming fluids at Campos Verdes crystals are recovered mainly from carbonate were aqueous solutions saturated with NaCl veins (Figure 2) in chlorite-carbonate-talc which also contained minor quantities of C02 schist and biotite schist. All these rocks and CH4. KCl, CaC^ and MgCl2 salts were also underwent ductile-brittle deformation and identified in these fluid inclusions. The origin shearing in a number of episodes under of the emerald-forming fluids was investi­ greenschist faciès metamorphism. gated by Fallick and Barros (1987) through Most of the gem mineralizations coincide stable isotope analyses. Their results indicated with the main phases of regional metamor­ a clear distinction between the H20 contained phism and only small quantities of gems are in the structural channels (ÔD = -39 ± 5%o), the found in the late-stage brittle fractures that H20 present in other parts of the emerald crosscut all the ductile structures in the area structure (ÔD = -50 ± 10%o) and the H20 in the (D'el-Rey Silva and Giuliani, 1988; Barros Neto fluid inclusions (ÔD = -156 ± -62%o). These and D'el-Rey Silva, 1995). Recently, Ribeiro- results suggest that the emerald-forming Althoff et al (1996) argued that the ages of the fluids were derived either from a magmatic mineralizations are close to 522 ± 1 Ma, based source or from the metamorphism of ultra- 254209 on K-Ar and 40Ar-39Ar ages of phlogopites basic rocks. formed with the emerald crystals. These chronological data are consistent with the Brasiliano Orogeny, which involved Gemmological properties reworking of older continental crust. The emeralds of the Campos Verdes The polyphase structural evolution of the mining district appear mainly as euhedral Campos Verdes mining district produced crystals which combine a first-order 1-10 m scale sheath folds with axes broadly hexagonal prism (1010) with a basal pinacoid parallel to the long axes of the deformed (0001). The size of these crystals is extremely pyrite, feldspar and quartz, which plunge variable, reaching up to 27 mm in length.

Figure 3: Back-scattered electron images illustrating (a) parallel inter growth and (b) growth striae on emerald crystal faces.

J. Gemm., 1998, 26, 4, 252-261 Figure 4: Photomicrographs of emerald crystals with sharply defined colour zones, (a) Colourless core surrounded by a green outer zone, (b) Green core enveloped by colourless outer zone.

Short prismatic crystals, parallel intergrown The densities obtained from transparent (Figure 3a), and radiating and irregular emeralds varied between 2.713 and crystal groups are common. All crystals 2.793 g/cm-3, whereas those crystals with show a strong parting perpendicular to the abundant solid inclusions showed values c-axis and striae parallel to this up to 2.8 g/cm-3. Under the gemmological crystallographic axis (Figure 3b). Rarely, the microscope, the emerald crystals in this crystals contain gradational colour zoning study were seen to contain one or more parallel to the basal pinacoid (0001), passing inclusions of the following: talc, from green to colourless. Concentric zoning phlogopite/biotite, carbonate, pyrite, beryl is also observed, which comprises a and quartz. Magnesite and dolomite 209255 colourless core enveloped by a green outer (Figure 5) were identified by X-ray zone (Figure 4a) or the opposite - a green core diffraction and not only occur as inclusions and a colourless outer zone (Figure 4b). but also fill emerald fractures. Inclusions of

Figure 5: Scanning electron image of dolomite crystals filling a fracture in emerald, and an X-ray diffractogram of the dolomite shown.

The chemical signature of emeralds from the Campos Verdes-Santa Terezinha Mining District, Goids, Brazil Analytical procedures Refractive indices of emerald crystals analyser. A weighed sample was mixed were measured with a Schneider with iron chips and a tungsten accelerator, refractometer on polished surfaces of and was then burned in an oxygen emerald crystals, and the crystal density atmosphere at 1370°C. The moisture and was determined in distilled water at room dust were removed and the COz gas and temperature using a hydrostatic balance. SOz gas were measured by a solid-state Emerald crystals apparently free of infrared detector. COz was determined by inclusions were washed with a dilute taking a second sample in a ceramic solution of HCl at 130°C, for 90 minutes, in crucible and adding 25% HCI dropwise order to remove carbonate from the until no reaction was observed. The fractures. The minerals were analysed by sample was dried on a hotplate at low X-ray diffraction, after that only samples temperature and C was redetermined on free of solid inclusions were selected for the dried residue. The difference was analysis by inductively coupled plasma calculated as COz' mass spectrometry (ICP-MS), Fourier The Massbauer analyses were performed transform infrared spectroscopy (FTIR) using absorbers prepared with appropriate and Massbauer spectroscopy (MS). amounts of ground (320 mesh) material in The X-ray diffraction analyses were order to satisfy the ideal absorber thickness carried out using a Siemens diffractometer approximation (Long et aI., 1983). Each equipped with CoKa tube, operating at sample, ground in an agate mortar, was 30 kV and 30 rnA, in the 2-80° 28 range. mildly compacted in a Plexiglas holder. The angles of diffraction spacings were The spectra were obtained at room 256174 measured with a precision of 0.026° 28. temperature (RT) using a constant 209256 Quartz powder was used as internal acceleration electromechanical drive standard. system with a multichannel analyzer for Emerald crystals without colour zoning collecting and storing the data. were analysed by rCP-MS. The contents of The volatile substances in the powder SiOz' TiOz' A1P3' MnO, MgO, CaO, Nap, of the emerald crystals were identified Kz0' PzOs' Crp3' BeO, Vps' Csp, SCP3' using a Galaxy series 3000 Fourier RbzO and LOr were determined by fusion; transform infrared spectrophotometer, FeO/Fez0 3 contents were measured by operating at room temperature, with a titration. The other elements (Ba, Sr, Y, Zr, precision of 4 cm-I . These analyses were Li, Cu, Pb, Zn, Ag, Ni, Cd and Bi) were done on powder pellets consisting of analysed by total digestion. emerald and KBr in the ratio 1: 100, The COz content was determined on an according to the technique described by automated LECO CS-344 carbon sulphur Russell (1974).

feldspar,feldspar, ankerite,ankerite, garnet, baryte, apatite, TheThe RIRI measurementsmeasurements suppliedsupplied relativelyrelatively chromite,chromite, picotite,picotite, actinoliteactinolite/tremolite / tremolite,, constantconstant averagesaverages withwith nono = 1.5901.590 toto 1.5931.593 andand glass,glass, rutile,rutile, hematite,hematite, limonite,limonite, ilmeniteilmenite nene = 1.5801.580 toto 1.587,, whilewhile thethe birefringencebirefringence andand magnetitemagnetite havehave alreadyalready beenbeen reportedreported rangedranged fromfrom 0.0.000055 toto 0.0.012012.. TheThe dichroismdichroism isis byby BankBank andand Petsch,Petsch, 1982;1982; BarrosBarros andand distinctdistinct andand thethe colourscolours areare greengreen IIHe c andand Kinnaird,Kinnaird, 1987b;1987b; Borelli,Borelli, 1986;1986; CassedanneCassedanne yyellowish-greeellowish-greenn .l±cc.. TheseThese emeraldemerald samplessamples andand Sauer,Sauer, 1984;1984; Fillmann,Fillmann, 1987;1987; GiulianiGiuliani showedshowed a reddishreddish glowglow whenwhen viewedviewed underunder andand Weisbrod,Weisbrod, 1988;; HanniHänni andand Kerez,Kerez, thethe GattingerGöttinger colourcolour filter,filter, butbut theythey areare inertinert 1983;1983; LindLind et al.al,, 1986;1986; MendesMendes andand Svisero,Svisero, underunder thethe ChelseaChelsea filterfilter andand toto long-long- andand short­short­ 1988. wavewave ultravioletultraviolet light.light.

J.J. GemmGemm.,., 11998,998,2 26,6,4, 4, 252252-261- 261 Table I: Compositions of emeralds fromfrom Campos VerdesVerdes obtainedobtained byby inductivelyinductively coupledcoupled plasmaplasma massmass spectrometryspectrometry (ICP-MS)

Sample VB-lOOO VB-3000 VB-4000 VB-SOOO VB-6000

coLour medium-green medium-green medium-green medium-green medium-green

wt. % Si02 59.22 63.42 63.82 60.44 63.50 ~O3 12.68 12.42 13.58 12.74 13.02 Fe20 3 1.52 1.77 1.21 1.67 1.54 FeO 0.62 0.25 0.26 0.25 <0.1 MnO 0.01 <0.02 <0.02 <0.02 <0.02 MgO 6.26 4.52 3.56 5.06 4.10 CaO 1.10 0.24 <0.02 1.38 0.18 Nap 2.32 2.36 2.34 2.32 2.36 ~O 0.06 0.10 0.06 0.04 0.08 Ti02 <0.01 <0.02 <0.02 <0.02 <0.02 P20 S <0.02 <0.02 <0.02 <0.02 0.06 Cr20 3 0.36 0.44 0.46 0.44 0.36 BeO 10.95 10.66 11.14 10.78 10.78 V20 S 0.07 0.08 0.06 0.06 0.06 Cs,O 0.10 0.10 0.10 0.10 0.10 SC20 3 0.20 0.22 0.18 0.20 0.18 Rbp <0.01 <0.02 <0.02 <0.02 <0.02 LOl 4.52 3.32 2.92 4.62 3.18 Total 99.99 99.90 99.69 100.10 99.50

wI. % CO2 2.27 0.54 0.08 2.24 0.34 ppm Ba 1 <2 <2 <2 <2 20925725 7 Sr 32 10 <2 38 6 Y <1 <2 <2 <2 <2 Zr <1 4 <2 4 <2 Li 30 24 38 28 28 Cu 2 2 5 3 2 Pb <5 <5 <5 <5 <5 Zn 7 4 8 7 2 Ag <0.4 <0.4 <0.4 <0.4 <0.4 Ni 97 44 40 44 37 Cd <0.5 <0.5 <0.5 <0.5 <0.5 Bi <5 <5 <5 <5 <5

ChemicalChemical signaturesignature IInn allall emeraldemerald samplessamples analysedanalysed (Table 1), I), TheThe compositiocompositionn ooff CamposCampos VerdesVerdes ththee elementselements FeFe,, Cr,Cr, NiNi,, Zn,Zn, ScSc andand V werweree alalll emeralemeraldd iiss summarizedsummarized inin Table 1. I.The Th eICP-MS ICP-M S presenpresentt inin detectabldetectablee quantitiesquantities.. TheThe large-iolarge-ionn resultresultss ooff emeralemeraldd samplessamples indicatindicatee a relativelyrelatively lithophillithophilee elementelementss (LILE(LILE,, Ba,Ba, Sr,Sr, RRbb andand PbPb)) constantconstant BBee contencontentt ooff 10.610.6 ttoo 11.211.2 wt.wt.%% BeBeOO andand ththee highhigh fieldfield strengthstrength elementselements (HFSE,(HFSE, Zr,Zr, andand variablvariablee quantitiequantitiess 11.9611.96 toto 13.5813.58 wt.% % ooff Y andand Ti)Ti) occuroccur inin amountsamounts neanearr oror belowbelow thethe detectiondetection limitslimits.. ThThee presencpresencee ooff ththee Cr-Ni-ZnCr-Ni-Zn A122003.. TheseThese resultresultss araree consistenconsistentt withwith previoupreviouss workworkss (Fillmann,(Fillmann, 1987;1987; Schwarz,Schwarz, associationassociation andand ththee lowlow contentcontentss ofof LILLILEE andand 1990).1990). IInn allall samplessamples therethere iiss fairfair correlationcorrelation HFSEHFSE suggestsuggest thethe contributiocontributionn ofof aann ultrabasicultrabasic component during the interaction between betweebetweenn CaCa + MgMg andand ththee COC02 contentscontents component during the interaction between (Table 1), I), which whic hsuggests suggest sthat tha thet th eanalyses analyse swere wer e fluidsfluids andand rocksrocks.. contaminatedcontaminated withwith carbonatecarbonate inclusions.inclusions. However,However, wewe havehave notnot recognizerecognizedd anyany Therefore,Therefore, ththee valuevaluess forfor CCaa anandd MMgg araree notnot systematicsystematic correlationcorrelation betweebetweenn thethe intensityintensity consideredconsidered inin relatiorelationn toto ththee emeralemeraldd structure.structure. ofof ththee greegreenn coloucolourr andand Cr3+Cr34 oror VV3+3+ quantities.quantities.

The chemical signature of emeralds fromfrom thethe CamposCampos Verdes-SantaVerdes-Santa TerezinhaTerezinha Mining Mining District,District, Gaids,Goids, Brazil Brazil 1.002 ,-----,-,-----,-,----,---,----,-----, TheThe valencevalence statestate ofof ironiron inin thethe CamposCampos VerdesVendes emeraldemerald samplessamples VB40VB40 andand VB3047VB3047 waswas investigatedinvestigated byby MossbauerMossbauer spectroscopy.spectroscopy. 1.000 TheThe spectraspectra obtainedobtained areare veryvery complexcomplex (Figure(Figure 6) andand resembleresemble quitequite closelyclosely thatthat 0.998 obtainedobtained byby ParkinParkin et al. (1977)(1977) forfor a blueblue berylberyl sample.sample. AlthoughAlthough itit waswas notnot possiblepossible toto fitfit thethe CamposCampos VerdesVerdes emeraldemerald spectra,spectra, theythey 0.996 3+ 2+ indicateindicate proportionsproportions ofof Fe3+ > Fe2+,, consistentconsistent o withwith resultsresults inin Table 1.I. Thus,Thus, accordingaccording toto 0.994 ligandligand fieldfield theorytheory itit isis reasonablereasonable toto expectexpect thatthat thethe varietyvariety ofof hueshues observedobserved inin thethe ~ 0.992 CamposCampos VerdesVerdes emeraldemerald samplessamples isis inin partpart ~ 3+ duedue toto thethe presencepresence ofof Fe3+ inin thesethese gems.gems. InIn c .,g 0.990 addition,addition, thethe valuesvalues ofof thethe birefringencebirefringence .n.... (~ o (A upup toto 0.012)0.012) andand thethe failurefailure ofof thethe emeraldsemeralds ~ ttoo respondrespond toto botbothh short-short- andand long­long- wavelengtwavelengthh ultravioleultraviolett lightlight probablyprobably cancan alsoalso bbee attributedattributed ttoo thethe FeFe contentcontent ofof thesethese gemsgems,, suchsuch asas hashas alreadyalready beenbeen suggestedsuggested byby GiibelinGübelin (1989)(1989) forfor PakistanPakistan emeraldemerald crystals.crystals. 0.999 AlkalAlkalii metalmetalss werewere detectedetectedd inin alalll CamposCampos 00 o VerdesVerdes emeraldemerald crystalscrystals,, whichwhich showshow o NaNa++ >Cs> Cs++ >Li> Li++ (Table I). ThThee averagaveragee LiLi o 0'1J o o 0

' 1.5 .VB3000 "

VB5000' , , 7.. 1.4 ." , U + + VB6000 & 1.3 VB1000•

1.2 VB4000

Regression Coeficient = -0.8986 1.1~-L~-L--'-~--"--~-L~LL~~-L~-L--'-~--"--~-L--'-LL~~-L~~ 6.5 6.6 6.7 6.8 6.9 7.0 7.1 7.2 7.3 AP+

J.,. Gemm.,Gemm., 1998,26,1998, 26, 44,, 252252-261 261 Table II: II: Comparison Comparison of HofH20 20contents contents in Campos in Campos Verdes Verdes emeralds emeralds with those with reported those byreported Aurissichio by Aurissichio et al. (1988) et al. (1988) and CheilletzCheilletz (1993) (1993) in emeraldsin emeralds from from other other deposits deposits.. ..

LocalityLocality SampleSample number number HpH20(wt.%) (wt.%) Reference MingoraMingora,, PakistaPakistann 4 2.202.20 HabachtalHabachtal,, AustriAustriaa 2323 22.6.60 CarnafbaCarnailia,, BraziBrazill 9 2.302.30 AurAurisicchiisicchioo etet aI.,al, 19881988 MuzoMuzo,, ColombiColombiaa 1100 22.4.400 UraUrall MountainsMountains,, USSUSSRR 2626 2.30 CarnafbaCarnailia,, BraziBrazill CATCATVV 2.422.42 CheilletzCheilletz etet aI.,al., 1993 199 3 VBVB-100-lOOO0 2.2S5 VB-300VB-30000 2.2.7788 CampoCamposs VerdesVerdes,, BraziBrazill VB-4000VB-4000 22.8.844 ThThiiss studystudy VB-500VB-SOOO0 2.382.38 VB-600VB-60000 22.8.844 relaterelatedd toto thethe Be-deficiencBe-deficiencyy accordinaccordingg ttoo thethe ThThee totatotall volatilevolatile contencontentt ooff thethe CamposCampos BBee <-+-+• LLii isomorphousisomorphous replacementreplacement VerdesVerdes gemsgems rangesranges fromfrom 2.92.922 toto 4.64.622 wt.%,wt.%, (Aurisicchio(Aurisicchio et a/.,al., 1988;1988; HawthorneHawthorne andand whilwhilee thethe C0CO22 contentcontent variesvaries betweebetweenn 0.080.08 CernyCerny,, 1977).1977). TheThe Al-deficiencAI-deficiencyy isis anandd 2.22.277 wt.% % (Table I). TheThe abundancabundancee ooff 3+ 3+ compensatecompensatedd bbyy (Fe + + CrCr3+)) aass indicatedindicated byby H200 maymay bebe estimatedestimated byby subtractionsubtraction ofof thethe ththee negativnegativee linealinearr correlatiocorrelationn betweebetweenn thesethese COCÖ2 frofromm ththee LOLOII content.content. ThusThus,, ththee totaltotal elementelementss (Figure 7). AnAnyy chargecharge deficiencydeficiency H2Ö0 contentscontents ofof CamposCampos VerdesVerdes emeraldemerald duduee ttoo suchsuch substitutionssubstitutions isis normallynormally crystalscrystals varvaryy betweebetweenn 2.252.25 andand 2.842.84 wt.wt.% %.. + + compensatedcompensated bbyy introductiointroductionn ofof NaNa+ andand Cs+Cs ThesThesee valuesvalues araree similarsimilar ttoo H200 contentcontentss ooff 209259259 intointo channelchannel sitessites (Aurisicchi(Aurisicchioo et al., 19941994;; emeralemeraldd crystalcrystalss frofromm otheotherr schistschist depositsdeposits HawthorneHawthorne andand CernyCerny,, 1977).1977). (Table II). ForFor example,example, AurisicchiAurisicchioo et al.

Figure 8: Fourier transform infrared (FTIR) spectrum from 400 to 1200 cm-cm'11 forfor emerald VB5000 fromfrom Campos Verdes.

Emerald Sample VB-SaO a

400 600 800 1000 1200 wavenumbers (em·')

The chemicalchemical signature signature of emeralds of emeralds from fromthe Campos the Campos Verdes-Santa Verdes-Santa Terezinha MiningTerezinha District, Mining Goids, District, Brazil Goids, Brazil 0.70 ,--,----,---,------,- ---,--,--.-----,---,----,------,--,--,--,---

Type II-HII-HP0 0.55 2 11626626 em-l1

Type II-H20 3655 eml1 ~ c~ 72~'"'" o Type II-HII-H 20

Sample VBVB-5000-5000 0.15 '-----'-_L--"-_-'-_-'--_ ...l...-'-----1._-'-_...l.-----'__ .l..-----1_-----L_-'-_-'--_L----L--'-_-L-_'----'-_-.L_-'------'_--..l_--'-_---L_-'----'_ -.l 1500 2000 2500 3000 3500 4000

wavenumberswavenumbers (em(em·-l1))

1 Figure 9:9: InfraredInfrared spectrumspectrum from from 1500--40001500-40001500-4:000 em-Iem cmr- I showing showing CO C02 2and and type type II IIH HpHzO20 peakspeaks in inemerald emerald from from Campos Verdes.Verdes.

-1I (1988)(1988) reportereportedd similarsimilar H200 quantitiesquantities inin showshow a peakpeak atat 23532353 cm-cm , whichwhich isis typicallytypically 260 2 show a peak at 2353 cm-I, which is typically emeraldsemeralds fromfrom [Iabachtal[fabachtalHabachtal (Austria),(Austria), CarnafbaCarnaiba 209260 causedcaused bbyy COC022 moleculesmolecules eithereither iinn thethe (Brazil),(Brazil), andand MingoraMingora (Pakistan).(Pakistan). channelchannel sitessites oror inin fluidfluid inclusionsinclusions (Wood(Wood InfraredInfrared spectroscopyspectroscopy analysesanalyses werewere donedone andand NassauNassau,, 1968).1968). TheThe waterwater peakpeakss areare ooff onon 1818 emeraldemerald powderpowder samples,samples, iinn orderorder toto highehigherr intensityintensity thanthan thethe C0CO22 peak,peak, whicwhichh isis identifyidentify volatilevolatile substancessubstances inin thesthesee gems.gems. consistentconsistent withwith thethe relativerelative contentscontents foundfound TheThe variousvarious spectraspectra obtainedobtained areare veryvery similarsimilar byby analysisanalysis (Table 1). D.I). inin thethe 400-1200400-1200 cm-cm"1I intervalinterval (Figure 8),8), exceptexcept forfor thethe vibrationvibration intensitiesintensities.intensities. ConclusionsConclusions AccordingAccording toto PlyusinaPlyusina (1964)(1964) thethe bandsbands inin thisthis rangerange areare typicaltypical forfor thethe berylberyl structure.structure. TheThe followingfollowing conclusionsconclusions cancan bebe drawndrawn fromfrom thethe investigationinvestigation:investigation: TheThe presencepresence ofof molecularmolecular species,species, suchsuch asas 1.1.Th Thee emeraldemerald samplessamples analysedanalysed fromfrom H200 andand COC02, cancan bebe easilyeasily recognizedrecognized inin thethe 2 2 CamposCampos VerdesVerdes showshow significantsignificant contentscontents FfIRFTIFTIRR spectraspectra (Figure 9) ofof thethe emeraldsemeralds fromfrom Campos Verdes show significant contents ofof Fe,Fe, Cr,Cr, V,V, Ni,Ni, Zn,Zn, ScSc andand alkalialkali metalsmetals CamposCampos Verdes.Verdës. WoodWood andand NassauNassau (1968)(1968) of Fe, Cr, V, Ni, Zn, Sc and alkali metals (Na »Cs > Ln, while LILE and HFSE are classifiedclassified waterwater moleculesmolecules asas type-lortype-Itype-I oror (Na»(Na » CsCs > Li),Li), whilewhile LILELILE andand HFSEHFSE areare near or below the detection limits. This type-II,type-II, dependingdepending onon whetherwhether thethe symmetrysymmetry nearnear oror belowbelow thethe detectiondetection limits.limits. ThisThis chemicalchemical signaturesignature suggestssuggests metasomaticmetasomatic vectorvector ofof H 200 moleculemolecule isis oriented,oriented, 2 exchanges between the emerald-forming respectively,respectively, perpendicularperpendicular oror parallelparallel toto thethe exchangesexchanges betweenbetween thethe emerald-formingemerald-forming fluidsfluids andand thethe ultrabasicultrabasic hosthost rocks.rocks. c-axis.c-axis. TheThe CamposCampos VerdesVerdes emeraldemerald samplessamples fluids and the ultrabasic host rocks. 3+ 2+ presentpresent bandsbands atat 1625-1627,1625-1627, 3591-35923591-3592 andand 2.2.Th Thee emeraldsemeralds containcontain Fe3+ andand Fe2+ inin -1I 3655-36583655-3658 cm-cm 1,, whichwhich indicateindicate thethe presencepresence quantitiesquantities sufficientsufficient toto influenceinfluence colour,colour, ofof type-IItype-II HzOHpH20 (Figure 9). TheThe predominancepredominance refractiverefractive indexindex andand otherother gemmologicalgemmological ofof thisthis kindkind ofof waterwater isis relatedrelated toto thethe alkalialkali properties.properties. contentcontent inin thethe berylsberyls asas suggestedsuggested byby 3.3.Th Thee infraredinfrared spectraspectra ofof thesethese emeraldsemeralds Hawthorne and Cerny (1977). The spectra of Hawthorne and Cerny (1977). The spectra of indicateindicate thethe presencepresence ofof type-IItype-II HzOH200 andand the Campos Yerdes emerald samples also , the Campos Y.erdes emerald samples also COCO,2.

J.J. Gemm.Gemm.,, 19981998,26,4,252-2611998,, 26, 4,4, 252-261252-261 AcknowledgementsAcknowledgements FiUmann,Fillmann, K.,K., 1987.1987. GefiigekundlicheGefügekundliche undund genetischegenetische AspekteAspekte vonvon EinschliissenEinschlüssen inin SmaragdenSmaragden TheThe authorsauthors wishwish toto thankthank DrDr OnildoOnildo J. ausgewahlterausgewählterLagerstätten.Diplomarbeit Lagerstatten. Diplomarbeit. . MariniMarini forfor researchresearch supportsupport andand thethe FachbereichFachbereich GeowissenschaftenGeowissenschaften derder JohanneJohanness GutenbergGutenberg UniversitatUniversität,, MainzMainz Minera<;aoMineraçao Peneri,Peneri, Minera<;aoMineraçao VerobiVerobi andand Giuliani, G.,G., D'el-ReyD'el-Rey Silva,Silva, L.JL.J.H..H.,, andand Couto,Couto, P,, 1990.1990. Minera<;aoMineraçao ItaobiItaobi forfor accessaccess andand logisticallogistical OriginOrigin ofof emeraldemerald depositsdeposits ofof Brazil.Brazil. MineraliumMineralium assistanceassistance duringduring fieldfield work,work, andand MsMs SilviaSilvia Deposita, 25,25, 57-{i457-64 M.M. BarretoBarreto forfor herher helphelp withwith thethe EnglishEnglish Giuliani, G., G., and and Weisbrod, Weisbrod, A., A, 1988. 1988. SEM SEM and and its application. its applica­ translation.translation. ThisThis researchresearch waswas financedfinanced byby tion. DeterminationDetermination ofof solidsolid andand daughterdaughter mineralsminerals inin fluidfluid inclusionsinclusions fromfrom somesome BrazilianBrazilian emeremeralaldd PADCTPADCT/FINEP-DNP /FINEP-DNPMM n065.94.0158.n°65.94.0158. FTIFTIRR deposits. InIn:: Congresso Latino-AmericanaLatino-Americano de Geologia, analysesanalyses werewere carriedcarried outout atat InstitutoInstituto dede 1988, Belém,Belem, Anais,Anais ,Belém. Belem SBG.. SBG. v.1, v.l, 445-57 445-57 Qufmica,Quîmica, UniversidadeUniversidade FederalFederal dodo RioRio Giibelin,Gübelin, E.J.,E.J., 1989. GemologicalGemological characteristicscharacteristics ofof GrandeGrande dodo SuISul (UFRGS)(UFRGS) andand ICPICP analysesanalyses atat PakistaniPakistani emeralds.emeralds. In:In: Emeralds of Pakistan - geologygeology,, Actab-Activation Laboratories Ltd., Ontario, gemology and genesgenesis.is. Geol.Geol. SurveySurvey ofof Pakistan.Pakistan. VanVan Actab-Activation Laboratories Ltd., Ontario, NostranNostrandd ReinholReinholdd Co.,Co., NeNeww York,York, 775-95-911 CanadaCanada.. SpecialSpecial thanksthanks areare duedue toto DDrr DD.. HanniHänni, H.AH.A..,, andand Kerez,Kerez, C.J.c.J.,, 1983.1983. NeueNeuess vomvom SchwarzSchwarz forfor a criticalcritical readinreadingg ofof thethe SmaragdvorkommenSmaragdvorkommen vonvon SantaSanta TerezinhaTerezinha ddee Goj,\s,Goiás, manuscript.manuscript. Brasilien.Brasilien. Z.Z. Dt.Dt. Gemma!.,Gemmol., Ges., 3232 (1),(1), 50-850-8 Hawthorne, F.C., EC., and and Cerny, Cerny, P., P., 1977. 1977. The The alkali-metal alkali-metal positions posi­ in Cs-Litions beryl. in Cs-Li Canadian bery!. Mineralogist, Canadian Mineralogist, 15, 414-21 15, 414-21 ReferencesReferences Lind,Lind, Th.,Th., HennHenn,, U., andand BankBank,, H.H.,, 1986.1986. SmaragdeSmaragde vonvon Sta.Sta. TerezinhTerezinhaa dede Goias,Goiás, BrasilienBrasilien,, mimitt relativrelativ hoherhoher AinesAines,, R.D.R.D.,, andand Rossman,Rossman, GG.R..R.,, 1984.1984. TheThe highhigh Lichtbrechung.Lichtbrechung. ZZ.. Dt.Dt. GGemmol.emmol. Ges., 35,35, 186--7186-7 temperaturtemperaturee behavioubehaviourr ofof waterwater andand carboncarbon dioxidedioxide inin Long,Long, G.J.,G.J., Cranshaw,, T.E., andand LongworthLongworth,, G.,G., 1983.1983. TheThe cordieritecordierite andand beryl.beryl. American Mineralogist,Mineralogist, 69, 319-27319-27 idealideal MössbaueMossbauerr absorbeabsorberr thicknessesthicknesses.. MössbauerMiissbauer Eff.Elf. AurisicchioAurisicchio,, C.c., Fioravanti,Fioravanti, GG..,, Grubessi,Grubessi, 0.O., andand Zanazzi,Zanazzi, Ref. Data J., 6, 42-942-9 P.F.,P.E, 1988. ReappraisalReappraisal ofof ththee crystacrystall chemistrychemistry ooff Mendes,, J.C.J.c., anandd Svisero,Svisero, D.P.D.P., 1988.1988. AAss incIusoeinclusões berylberyl.. American Mineralogist,Mineralogist, 73,73, 826-37826-37 cristalinascristalinas e fluidasfluidas dada esmeraldaesmeralda dede SantaSanta TerezinhaTerezinha AurisicchioAurisicchio,, C.c., Grubessi, 0.O., anandd Zecchini,, P.,P., 19941994.. dede GoiasGoiás e seuseu significadsignificadoo geológicageologica.. In:: Congresso InfrareInfraredd spectroscopspectroscopyy anandd crystacrystall chemistrychemistry ooff thethe Brasileiro de Geologia, 3535,, 1988,1988, BelémBelem,, Anais,, BelemBelém, 209261261 beryberyll groupgroup.. Canadian Mineralogist, 3232,, 55-<>855-68 SBGSBG.. v.lv.l,, 445-50445-50 BankBank,, H.H.,, anandd PetschPetsch,, E.E.,, 1982.1982. Übetiberr eieinn neueneuess VorkommenVorkommen Nassau,, K.,, 1983.1983. TheThe physics and chemistry of colour - the vovonn SmaragSmaragdd bebeii SantaSanta TerezinhaTerezinha,, GoyásGoyas,, Brasilien.Brasilien. fifteenfifteen causes of colour. JohnJohn WileyWiley && Sons,Sons , NewNew York,York , Z.. Dt.Dt. Gemmol. Ges., 3311 (1/2)(1/2),, 89-9089-90 pp.454. 454 BarrosBarros,, J.G.C.J.G.c.,, anandd KinnairdKinnaird,, J.A.J.A,, 1987a.Inc1us6es1987a. Inclusões fluidasfluidas ParkinParkin,, K.M., LoefflerLoeffler,, B.M.B.M.,, anandd BurnsBurns,, R.G.R.G.,, 19771977.. eemm esmeraldaesmeraldass e beriloberiloss verdeverdess ddoo EstadEstadoo ddee Goias.Goiás. MössbaueMossbauerr spectrspectraa ooff kyanitekyanite,, aquamarinaquamarinee andand 3232'a ReuniãoReuniiio da SBPC, BrasiliaBrasilia,, g.5, f.3f.3,, 643643 cordieritcordieritee showinshowingg intervalencintervalencee chargchargee transfertransfer.. Phys. BarrosBarros,, J.G.C.J.G.c.,, anandd KinnairdKinnaird,, J.A.J.A.,, 1987b1987b.. EmeraldEmeraldss fromfrom Chem.Chem . Minerals,Minerals, 1,1, 301-11301-11 GoiáGoiass State-BrazilState-Brazil.. XXXXII InternationaInternationall GemmologicalGemmological PlyusinaPlyusina,, I.I.I.I.,, 19641964.. InfrareInfraredd absorptioabsorptionn spectrspectraa ooff beryls.. Conference,, RiRioo ddee Janeiro, AbstractsAbstracts GeochemistryGeochemistry International,International, 13-2113-21 Barross Neto,, L.S.L.S.,, anandd D'el-ReD'el-Reyy Silva,, L.J.H.L.J.H.,, 19951995.. Ribeiro-Althoff, , A.M.A.M.,, CheilletzCheilletz,, A.A.,, Giuliani,, G.G.,, FeraudFéraud, EvoluçãEvoluc;aoo estruturaestruturall ddoo distritdistritoo esmeraldíferesmeraldfferoo dede G.,, Zimmermann,, J.L.J.L.,, BarbosBarbosaa Camacho,, G.G.,, andand CampoCamposs VerdesVerdes,, GoiásGoias.. V SimpósioSimp6sio Nacional de EstudosEstud05 Robert,Robert ,P., P. ,1996. 1996 .Dataçôes Datac;5es K-Ar K-Ar e 40 eAr/ 4OAr/39Ar39 deAr mineralizações de miner­ TectônicosTectOnicos (Gramado),(Gramado), 337-9337-9 alizac;6es ddee esmeraldesmeraldaa ddoo BrasilBrasil.. XXXIX CongressoCongresso BorelliBorelli,, A.A,, 19861986.. OsservazionOsservazionii sullsuIlee inclusioninclusionii solidsolidee degldeglii BrasileiroBrasileiro de GGeologia,eologia, Salvador,Salvador, 324'-8 324-8 smeraldsmeraldii ddii SantSantaa TerezinhTerezinhaa dee GoiaGoiass (Brasile)(Brasile).. LaLa RibeirRibeiroo FilhoFiIho,, W.W.,, 19811981.. ReavaliaçãReavalia~aoo ddaa GeologiGeologiaa ddee PilarPilar­- Gemmologia,Gemmologia, XXII (3)(3),, 6--106-10 MarMaraa Rosa.. I SimpósioSimp6sio de Geologia do Centro OOeste,este, BosshartBosshart,, G.G.,, 19911991.. EmeraldEmeraldss frofromm ColombiColombiaa (Par(Partt 2)2).. GoiâniaGoiania,, 281-9281-966 Journ.Journ. Gemmol., 2222 (7)(7),, 409-25409-25 RussellRusseIl,, J.D.J.D.,, 1974.. InstrumentatioInstrumentationn anandd techniquestechniques;; iinn ThThee CassedanneCassedanne,, J.P.J.P.,, anandd SauerSauer,, D.A.D.A.,, 19841984.. ThThee SantaSanta infrareinfraredd spectrspectraa ooff mineralsminerals.. Mineralogical SocietySociety TerezinhTerezinhaa ddee GoiáGoiass emeralemeraldd depositdeposit.. Gems & Monograph,Monograph , 4, 11-2511-25 Gemology, 2020,, 9-149-14 SchwarzSchwarz,, D.D.,, 19901990.. DiDiee brasilianischebrasilianischenn SmaragdSmaragdee unundd ihrihree D'el-ReD'el-Reyy SilvaSilva,, L.J.H.,, anandd GiulianiGiuliani,, G.G.,, 19881988.. ControleControle VorkommenVorkommen:: SantSantaa TerezinhTerezinhaa ddee Goiás/GOGoias/ GO.. ZZ.. DtDt.. estruturaestruturall ddaa jazidjazidaa ddee esmeraldaesmeraldass ddee SantSantaa TerezinhaTerezinha Gemmol.Gemmol. Ges.,Ges., 3399 (1)(1),, 13-4413-44 ddee GoiásGoms:: implicaçõeirnplicaC;5ess nnaa gênesegenese,, nnaa tectônictectonicaa regionaregionall Souza,, J.O.J.O.,, anandd LeãLeaoo NetoNeto,, R.R.,, 19841984.. MapeamentoMapeamento e nnoo planejamentplanejamentoo ddee lavra.. XXXXXXVV CongressoCongresso BrasileiroBrasileiro geológicgeologicoo ddoo garimpgarimpoo ddee esmeraldaesmeraldass ddee SantSantaa dede Geologia, Belem,Belém, 413-27413-27 TerezinhTerezinhaa ddee GoiásGoias.. UnpublUnpub!'. RepRep.. DNPM/CPRDNPM/ CPRMM -- FallickFallick,, A.E.A.E.,, anandd Barros,, J.G.J.G.,, 19871987.. A stable-isotopestable-isotope ProjetProjetoo EstudEstudoo ddee GarimpoGarirnposs BrasileiroBrasileiross investigatioinvestigationn intintoo ththee origioriginn ooff beryberyll anandd emeraldemerald WoodWood,, L.L.L.L.,, anandd NassauNassau,, K.K.,, 19681968.. ThThee characterisatiocharacterisationn ooff frofromm ththee PorangatPorangatuu depositsdeposits,, GoiáGoi<\ss StateState,, BrazilBrazil.. beryberyll anandd emeralemeraldd bbyy visiblvisiblee anandd .infraredinfrared absorptionabsorption Chemical Geology, 66,66, 293-300293-300 spectroscopyspectroscopy.. AmericanAmerican Mineralogist, 5353,, 777-80777--8000

The chemical signaturesignature of emeraldsemeralds from the Campos Verdes-Santa Terezinha MiningMining DiDistrict,strict, Goids,Goiâs, Brazil Brazil An interdisciplinary approach to identifying solid inclusions in corundum: thorite in a 'Sri Lanka' sapphire Susanna Carbonin1, Gino Sbrignadello2 and David Ajò2 1. Dipartimento di Mineralogia e Petrologia, C.so Garibaldi 37, 35137 Padova, Italy 2. Istituto di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati, CNR, Corso Stati Uniti 4, 35127 Padova, Italy

ABSTRACT: A blue sapphire of commercial provenance examined using a transmitted-light microscope revealed at least two different types of inclusions. One was considered to be an idiomorphic spinel with an appreciable content of Cr3+, and the second, a metamict zircon. A more complete characterization by EDS microanalysis and gamma- spectrometry led to identification of the latter inclusion as thorite

(ThSiO4). This report emphasizes the desirability of using completely 262 independent techniques when dealing with complex identification problems. 209 Keywords: gamma-spectrometry, sapphire, Sri Lanka, solid inclusions, spinel, thorite

Introduction materials is presently in preparation. However, we think it is useful at this stage to • ^m eports have been published recently briefly demonstrate the value of a multi- Ê^T (Ajö et al, 1996a; Carbonin et ah, disciplinary approach to chemical, structural JL m. 1998) on the application of and morphological features of corundum. photoluminescence (PL) spectroscopy to gemmological problems. The PL technique was successfully employed by some of us, in addition to the more usual methods, in the Results and discussion investigation of minerals and of their A 'classic7 blue sapphire was one in a synthetic analogues. These studies are of series of samples kindly provided by interest in different fields, among which are Mr Silvano Bettella (Settore Orafo, gemmology, laser material production Confederazione Nazionale Artigianato (Barba et al., 1997) and works of art (Ajo et ah, (C.N.A.), Padova), whose experience (in the 1996b). absence of reliable information about its A comprehensive discussion concerning provenance) induced us to ascribe it to the our studies of corundum and related 'Sri Lanka' type.

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355^565 Observation by means of transmitted- light microscopy revealed at least two different types of inclusions. The first kind of solid inclusion (Figure 1) is associated with 'fingerprints' and its red colour and habit led us to think it was an idiomorphic spinel octahedron, reported as a typical feature of Sri Lanka sapphires by Gübelin and Koivula (1992) and Webster (1994). Since a red spinel should have an appreciable concentration of Cr3+, we recorded a photoluminescence (PL) spectrum of this material using a He-Ne (X = 632.8 nm, 25 mW) laser. Most sapphires, blue or even colourless (Ajö et al, 1996a; Figure 1: Idiomorphic octahedral inclusion in Carbonin et al, 1998), and spinels transmitted light (50x). investigated so far contain enough chromium to give rise to a PL spectrum. in order to confirm the assignment we The He-Ne excited PL spectrum exhibited resorted to a much more intense Ar the well-known Cr3+ (Ajö et al, 1996a) (k = 488.0 nm, 1.5 W) source (Figure 2). emission from the host sapphire but it was much weaker and noisier than those of On examination through a microscope, materials previously studied by He-Ne (Ajö the second solid inclusion (Figure 3) showed et al, 1996a; Carbonin et al, 1998). Therefore, the typical habit and tension-halos and 209263

Figure 2: Ar-excited PL spectrum of the sapphire.

An interdisciplinary approach to identifying solid inclusions in corundum: thorite in a 'Sri Lanka' sapphire Conclusions The above results indicate the value of using completely independent techniques - in the present case related to electronic (valence and core) and nuclear energy levels - when dealing with complex identification problems. In particular, we have shown that some caution is needed when an inclusion is attributed to zircon on the basis only of optical and morphological properties. Finally, our findings concerning solid inclusions indicate the possibility of Figure 3: Thorite inclusion about 45 um long, considering another mineral species in deter­ resembling zircon, transmitted light (lOOx). mining the provenance of a sapphire.

fissures of a metamict zircon grain (Gübelin Acknowledgements and Koivula, 1992; Webster, 1994). This inclusion appeared close to the surface of the The authors gratefully thank host crystal, and during preparation of the Dr A. Speghini (1st. Policattedra Facoltà di sapphire for electron probe microanalysis, it Scienze, University, Verona) for recording the was thought worthwhile to determine the Ar-excited PL spectrum, and Dr C. Brogiato nature of this inclusion by polishing the and Mr L. Tauro (Dipart. Mineralogia e sapphire until the level of the inclusion was Petrologia, University, Padova) for pictures 264209 reached and then analysing it. and for carefully polishing the sapphire, respectively. Surprisingly, once the electron beam was focused on the extremely small polished area, no characteristic Zr radiation was References detected by means of the energy dispersive system (EDS). Instead, together with the Ajò, D., De Zuane, F., Favaro, M.L., Pozza, G., Bettella, already expected silicon Ka, various wave­ S., 1996a. Photoluminescence of minerals and synthetic materials. In: Daolio, S., Tondello, E., lengths were present that could be ascribed Vigato, P.A. (Eds), Syntheses and methodologies in to thorium: among these the most intense inorganic chemistry: new compounds and materials, were Mal, Ma2 (2.996, 2.986 keV) and Mß Litografia 'la photograph', Albignasego, Vol. 6, (3.145 keV). No other major peaks were p. 342-7 present and the possibility that the mineral Ajò, D., Chiari, G., De Zuane, E, Favaro, M.L., Bertolin, M., 1996b. Photoluminescence of some blue natural was thorite (ThSi04) is supported by the pigments and related synthetic materials. In: habit which is very similar to that of zircon. Proceedings V Internat. Conf. non-destructive testing, microanal. methods and environm. eval. for study and Due to the extremely small size of the conservation of works of art (Budapest, 24-28/9/96), crystal under investigation, we thought further Budapest, pp 696 support for our identification using a different Barba, M.F., Callejas, P., Ajò, D., Pozza, G., Bettinelli, M., technique was necessary. So, using gamma- 1997. Near-IR photoluminescence of manganese (V)- spectrometry with a low-background configu­ doped synthetic materials and related minerals. Ceramic Engin. Sci., Proc., 18 (2), 22-7 ration n-type intrinsic germanium detector Carbonin, S., Visonà, D., Rizzo, I., Favaro, M., Pozza, G., equipped with an epoxy window, the presence Ajò, D., 1998. Optical properties and composition of 232 of natural Th in the sample was definitively corundum and of synthetic and mineral related confirmed. The identification was possible minerals. In: Inst. Phys. Conf. Ser. No. 152; Section G, through the gamma emission of daughters 827-30 212 208 Gübelin, E.J., Koivula, J.I., 1992. Photoatlas of inclusions in Pb and T1 at 238.6 keV (44.7% probability) gemstones. ABC Ed., Zurich, 532 pp and 583.1 keV(84.2%), respectively. Webster, R., 1994. Gemme. Zanichelli, Bologna, 1231 pp

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The treatment of samples of suevite from Black Diamonds Onaping, Sudbury, Ontario, has revealed the presence of diamonds. Their morphology, optical properties, X-ray data Gem news - the 26th International Gemmological and e.p.r. spectra show the surface and polycrystalline state Conference. of the cubic phase and prove the impact origin of the diamonds. Three forms of carbonaceous material, including M.L. JOHNSON AND J.I. KOIVULA. Gems & Gemology, 33(4), shocked and single-crystal graphite, were found together 1997,298-310, 15 illus. in colour. with diamonds, having probably originated by the Cathodoluminescence could be used to help determine transformation of graphite in the target rocks. R.A.H. the diamond type with a possible classification of mixed types given. Diamond and graphite inclusions have been found in sapphires from Ban Huai Sai, Laos. Major mineral A contribution to understanding the effect of blue inclusions in large Yakutian diamonds were found to be fluorescence on the appearance of diamonds. sulphides, olivine and chromite, with the proportions T.H. MOSES, I.M. REINITZ, M.L. JOHNSON, J.M. KING AND J.E. varying from mine to mine. Three growth morphologies are SHiGLEy. Gems & Gemology, 33(4), 1997, 244-59, 9 illus. found in natural diamonds; octahedral being the most in colour, 3 tables. common and forming the majority of gem material, cuboid Over the last few decades diamond dealers thought of which only a portion forms gem material and fibrous that fluorescence in diamonds had a negative effect on the which never yields gem-quality diamonds. J.J. overall appearance of the stone. Under concentrated LW 266 ultraviolet radiation some diamonds fluoresce blue and Mineral inclusions in diamonds from the River this should be used as an identifying feature rather than a grading factor by gem testing laboratories. The GIA GTL Ranch kimberlite, Zimbabwe. investigated the effect of blue fluorescence on colourless M.G. KORYLOVA, J.J. GURNEY AND L.R.M. DANIELS. to faint yellow diamonds when viewed from various Contributions to mineralogy and petrology, 129, 1997, positions under different lighting conditions. Four sets of 366-84. six stones were chosen, which were similar in all respects Mineral inclusions in diamonds from the River Ranch (clarity, size, etc.) except fluorescence. The observers kimberlite pipe in Zimbabwe are almost entirely composed ranged from diamond dealers to people outside the trade. of phases of harzburgitic paragenesis (olivine (Fo92), Only the experienced observers found any difference and orthopyroxene (En93)), G10 garnets and chromites. The their responses varied, but a correlation was found pipe is situated in the Late Archean Limpopo Mobile Belt between viewing position and fluorescence. Strong blue (LMB). Inclusion studies are used to assist the assignment of fluorescing diamonds were thought to have a better the tectonothermal age of the LMB and strengthen the colour appearance when viewed from the table down. theory that an ancient thick mantle root existed beneath the Otherwise no relationship between fluorescence and Belt about 530-540 million years ago. M.O'D. transparency was found. These results show that it is best to judge each diamond on its own visual merits. J.J. [Diamonds in suevites of the Sudbury impact structure, Canada.] (Russian with English abstract) Gem Trade Lab notes. V.L. MASAITIS, G.I. SHAFRANOVSKY, R.A.F. GRIEVE, T.H. MOSES, I.M. REINITZ AND S.F. MCCLURE. Gems & W.V. PEREDERY, E.L. BALMASOV AND I.G. FEDOROVA. Gemology, 33(4), 1997, 292-6, 7 illus. in colour. Proceedings of the Russian Mineralogical Society, 26(4), Diamonds can crack spontaneously without any 1997,1-6. apparent cause, but this could be linked to high amounts

Abstractors

R.K. Harrison R.K.H. J. Johnson J.J. P.G. Read P.G.R. R.A. Howie R.A.H. M. O'Donoghue M.O'D. E. Stern E.S. G. Raade G.R. P.J. Treloar P.J.T.

For further information on many of the topics referred to, consult Mineralogical Abstracts

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 ofof strainstrain withiwithinn thethe stonestone.. A squaresquare cutcut diamonddiamond ooff SyngeneticSyngenetic inclusionsinclusions inin diamonddiamond fromfrom thethe saturatedsaturated pinpinkk colourcolour withwith abundantabundant fracturesfractures waswas BirimBirim fieldfield (Ghana)(Ghana) - a deepdeep peridotitiperidotiticc profileprofile examinedexamined anandd afterafter fracturefracture fillingfilling procedurproceduree thethe colourcolour withwitHETh a historhistoryKASTEELy ofof depletiondepletion andand re-enrichment.re-enrichment. appearanceappearance waswas muchmuch enhanced,enhanced, althoughalthough thethe clarityclarity waswas T.T. STACHELSTACHEL ANANDD J.W.J.W. HARRIS.HARRIS. Contributions to Mineralogy nonott significantlysignificantly improved.improved.J.J J.J.. and Petrology, 127(4),127(4), 1997,1997, 336-52.336-52. TheThe physicalphysical propertiesproperties (size,(size, shape,shape, colour,colour, deformation,deformation, inclusioninclusion assemblage,assemblage, N content,content, % BB,, type,type, Radiation-inducedRadiation-induced diamonddiamond crystallization:crystallization: originorigin 013C,ô13C, 015N)ô15N) ofof diamondsdiamonds fromfrom placerplacer depositsdeposits ofof thethe ofof carbonadoscarbonados anandd itsits implicationsimplications onon meteoritemeteorite AkwatiaAkwatia mine,mine, southernsouthern Ghana,Ghana, areare tabulatedtabulated andand thethe nano-diamonds.nano-diamonds. inclusioninclusion abundanceabundance isis reportedreported foforr 693693 inclusion-bearinginclusion-bearing MM.. OZIMAOZIMA ANDAND M.M. TATSUMOTO.TATSUMOTO. Geochimica etet Cosmochimica diamonds.diamonds. InIn comparisoncomparison withwith a worldwideworldwide databasedatabase forfor 11001100 diamonddiamond inclusions,inclusions, thethe AkwatiAkwatiaa inclusionsinclusions havehave Acta, 61(2),61(2), 1997,1997, 369-76.369-76. olivinesolivines witwithh lowerlower Mg/FeMg/Fe ratiosratios andand extremelyextremely highighh NiNi AnalysesAnalyses areare presentedpresented ofof 1010 carbonadoscarbonados fromfrom CentralCentral contents.contents. GeothermometryGeothermometry showsshows thethe AkwataianAkwataian AfricaAfrica,, forfor U-U-Th-PTh-Pbb elementselements andand isotopes,isotopes, andand ofof inclusionsinclusions toto bebe 140-190°C140-190°C hotterhotter thanthan thethe peridotiticperidotitic Y,Th-deriveY,Th-derivedd noblenoble gases.gases. OnOn thethe basibasiss ofof thethe U-U-Th-PTh-Pbb averageaverage (1050°C)(1050°C),, andand sincesince garnet-orthopyroxenegarnet-orthopyroxene equilibria (1100°C/50 kbar to 1370°C/67 kbar) indicate a systematicssystematics a modelmodel isis proposedproposed forfor thethe originorigin ofof equilibria (1100°C/50 kbar to 1370°C/67 kbar) indicate a 22 typicaltypical shieldshield geothermgeotherm (40-42(40^2 mWmW/m /m )),, thesethese elevatedelevated carbonadoscarbonados iinn whichwhich radiation-induceradiation-inducedd diamonddiamond temperaturestemperatures implyimply anan originorigin forfor thethe AkwatiAkwatiaa diamondsdiamonds crystallizationcrystallization isis involved.involved. ThisThis mechanismechanismm maymay bebe relevantrelevant unusuallyunusually deepdeep forfor a peridotiticperidotitic suite.suite. ItIt isis consideredconsidered thatthat toto thethe origioriginn ofof nanodiamondsnanodiamonds iinn primitivprimitivee meteorites.meteorites. A thethe inclusionsinclusions inin thesethese diamondsdiamonds representrepresent ththee mostmost minimumminimum agagee ofof 26002600 m.y.m.y. andand a maximummaximum ageage ofof 38003800 m.m.y y.. completecomplete cross-sectioncross-section throughthrough peridotiticperidotitic subcontinentalsubcontinental areare assignedassigned toto thethe radiogenicradiogenic PbPb bbyy assumingassuming instantinstant lithosphericlithospheric upperupper mantlemantle soso farfar observed,observed, dowdownn ttoo a productioproductionn oorr integratedintegrated productioproductionn frofromm radioactiveradioactive decaydecay maximummaximum depthdepth ofof 200-240200-240 km.km.R.A.H R.A.H.. ofof U.U. TheThe radiogenicradiogenic PbPb inin ththee carbonadoscarbonados waswas implantedimplanted fromfrom ititss surroundingssurroundings duedue toto thethe a-recoila-recoil ofof radiogeniradiogenicc Pb.Pb. DiamantenDiamanten ausaus China.China. 4 ExcessExcess radiogeniradiogenicc PbPb andand fissionfission Xe,Xe, KrKr andand 4H Hee iinn G.G. STEINER.STEINER. Lapis, 22(11),22(11), 1997,1997,13-17, 13-17, 11 mapmap inin colour.colour. carbonadoscarbonados suggestssuggests thatthat energeticenergetic particlesparticles emittedemitted byby U TheThe presencpresencee ofof diamonddiamond inin thethe territoryterritory composingcomposing andand TThh changechangedd carbonaceouscarbonaceous precursorprecursor materialmaterial toto present-daypresent-day ChinaChina hashas beenbeen knownknown asas lonlongg agoago asas thethe diamond,diamond, thethe crystallizationcrystallization ageage ofof microdiamondmicrodiamondss inin fourthfourth century.century. SeveralSeveral ChineseChinese authoritiesauthorities areare citecitedd inin 209267 carbonadoscarbonados beinbeingg 2600-38002600-3800 m.y.m.y.R.K.H RK.H.. supportsupport ofof thisthis viewview.. TodayToday atat leastleast 1414 majormajor sitesitess havehave 261 beebeenn identifiedidentified andand threethree majormajor platformsplatforms accommodateaccommodate bothboth peridotiteperidotite andand lamproite-housedlamproite-housed diamonddiamond deposits.deposits. TheThe PremiePremierr mine,mine, Pretoria,Pretoria, SouthSouth Africa.Africa. TodayToday aboutabout oneone millionmillion caratscarats ofof diamonddiamond areare recoveredrecovered annuallyannually andand detailsdetails ofof thethe occurrenceoccurrence andand workingworking ofof thethe R. SANCROFT-BAKERSANCROFT-BAKER.. Christie's Jewellery Review 1997, 1998,1998, Chang-rnaChang-ma kimberlitekimberlite pipepipe areare given.given. ThisThis areaarea isis alreadyalready 14-15,14-15, illusillus.. inin colour.colour. responsibleresponsible forfor notablenotable crystals.crystals.M.O'D M.O'D.. ShortShort accountaccount ofof a visitvisit paidpaid toto thethe PremierPremier diamonddiamond mine,mine, PretoriaPretoria,, SouthSouth Africa.Africa. DetailsDetails ofof ththee locallocal geologygeology MetamorphicMetamorphic evolutionevolution ofof diamond-bearingdiamond-bearing andand andand ofof ththee recoveryrecovery ofof diamondsdiamonds areare given.given.M.O'D M.O'D.. associatedassociated rocksrocks fromfrom thethe KokchetavKokchetav Massif,Massif, northernnorthern Kazakhstan.Kazakhstan. MineralMineral inclusioninclusionss inin diamondsdiamonds fromfrom thethe SputnikSputnik R. ZHANG,ZHANG, J.G.J.G. LIou,LIOU, RG.R.G. COLEMAN,COLEMAN, N.VN.V.. SOSOLEVSOBOLEV ANANDD V.S.V.S. SHATSKY.SHATSKY. Journal of Metamorphic Geology, 15(4),15(4), 1997,1997, kimberlitekimberlite pipe,pipe, Yakutia.Yakutia. 479-96.479-96. N.V.N.V. SOSOLEV,SOBOLEV, EV.RV. KAMINSKY,KAMINSKY, W.L.W.L. GRIFFIN,GRIFFIN, E.s.E.S. YEFIMOVA,YEFIMOVA, RepresentativeRepresentative diamond-bearingdiamond-bearing gneissesgneisses andand T.T.T.T. WIN,WIN, CG.CG. RYANRYAN ANDAND A.I.A.I. BOTKUNOV.BOTKUNOV. Lithos,Lithos, dolomiticdolomitic marblemarble,, eclogiteeclogite andand Ti-clinohumite-bearingTi-clinohumite-bearing 39(3--4),1997,135-57.39(3-4), 1997,135-57. garnetgarnet peridotiteperidotite fromfrom KumduKumdu KolKol andand whiteschistwhiteschist fromfrom KuletKulet werweree studied.studied. Diamond-bearingDiamond-bearing gneissesgneisses containcontain TheThe SputnikSputnik kimberlitekimberlite pipepipe isis a smallsmall satellitesatellite ofof thethe variablevariable assemblagesassemblages includingincluding GrtGrt + BtBt + QtzQtz ± PPII ± KfsKfs largerlarger MirMir pippipee inin centralcentral YakutiaYakutia (Sakha),(Sakha), Russia.Russia. StudyStudy ± ZoZo ± ChiChi ± TurTur ± CalCal andand minorminor Ap,Ap, RtRt andand Zrn;Zrn; ofof 38 largelarge diamonddiamondss (0.7-4.9(0.7-4.9 ct)ct) showedshowed thathatt ninenine containcontain abundantabundant inclusionsinclusions ofof diamond,diamond, graphitegraphite + chloritchloritee (or(or inclusionsinclusions ofof thethe eclogiticeclogitic paragenesisparagenesis,, whilewhile thethe calcite),calcite), phengite,phengite, clinopyroxene,clinopyroxene, K-feldspar,K-feldspar, biotite,biotite, remainderemainderr contaicontainn inclusionsinclusions ofof ththee peridotitiperidotiticc paragenesis,paragenesis, rutile,rutile, titanite,titanite, calcitecalcite andand zirconzircon occuroccur inin garnet.garnet. Diamond-bearing dolomitic marbles consist of Dol + Di ± oror ofof uncertaiuncertainn paragenesis.paragenesis. TheThe peridotitiperidotiticc inclusioinclusionn suitesuite Diamond-bearing dolomitic marbles consist of Dol + Di ± GrtGrt + Phi;Phi; inclusionsinclusions ofof diamond,diamond, dolomitedolomite ± graphite,graphite, comprisescomprises olivine,olivine, enstatite,enstatite, Cr-diopside,Cr-diopside, chromite,chromite, Cr­Cr- biotitbiotitee andand clinopyroxeneclinopyroxene werewere identifiedidentified inin garnet.garnet. OtherOther pyropepyrope (both(both Iherzoliticlherzolitic andand harzburgitic)harzburgitic),, ilmenite,ilmenite, Ni­Ni- ultrahigh-pressureultrahigh-pressure (UHP)(UHP) indicatorsindicators includeinclude Na-bearingNa-bearing richrich sulphidesulphide andand a Ti-Cr-Fe-Mg-Sr-KTi-Cr-Fe-Mg-Sr-K phasephase ofof thethe garnetgarnet ("(s 0.140.14 wt.%wt.% Nap)Na20) withwith omphaciteomphacite CpCpxx inin lindsleyite-mathiasitelindsleyite-mathiasite series.series. TheThe eclogiticeclogitic inclusioninclusion suitesuite eclogite,eclogite, occurrenceoccurrence ofof high-Khigh-K diopsidediopside ("(<; 1.561.56 wt.wt.%% KP)K20) comprisescomprises omphaciteomphacite,, garnet,garnet, Ni-poorNi-poor sulphide,sulphide, high-high-TTii andand phlogopitphlogopitee inin diamond-bearingdiamond-bearing dolomiticdolomitic marble,marble, phlogopitephlogopite anandd rutile.rutile.G.R G.R. andand Cr-bearingCr-bearing kyanitekyanite inin whiteschist.whiteschist.P.J.T P.J.T..

Abstracts - Diamonds AussergewöhnlicheAussergewohnlicherr QuarzfunQuarzfundd iimm VallVallee Gems and Minerals BedrettoBedretto,, TessinTessin.. GemsNeue andSmaragdfunde Miners aus Chile, Siidamerika. DD.. DONATIDONATI,, RR.. GUERRAGUERRA,, NN.. OPPIZZOPP=II ANANDD PP.. OPPIZZIOPP=J.. Lapis,Lapis, Neue Smaragdfunde aus Chile, Südamerika. 23(2)23(2),1998,31-5,, 1998,31-5, illusillus.. iinn colourcolour.. A.G. BANKO, F. BRANDSTATTER, G. NIEDERMAYR AND A.G. BANKO, F. BRANDSTÄTTER, G. NIEDERMAYR AND ExtraordinarilExtraordinarilyy larglargee crystalcrystalss ooff smoksmokyy quartquartzz havhavee J. KARFUNKEL. Gemmologie (Zeitschrift der Deutschen J. KARFUNKEL. Gemrnologie (Zeitschrift der Deutschen beebeenn founfoundd neanearr ththee ValleggiValleggiaa glacieglacierr iinn ththee VallVallee Gemmologischen Gesellschaft!, 46, 1997, 213-24. 16 Gemmologischen Gesellschaft), 46, 1997, 213-24. 16 BedrettoBedretto,, TicinoTicino,, SwitzerlandSwitzerland.. ThThee largeslargestt crystacrystall ssoo farfar photographs, 3 graphs, 4 tables, bib!. photographs, 3 graphs, 4 tables, bibl. founfoundd measuremeasuress 9922 ccmm iinn lengthlength,, 4455 ccmm iinn thicknessthickness,, OnOnee neneww occurrencoccurrencee ooff emeraldemeraldss iiss highighh iinn ththee AndesAndes,, weighinweighingg 151500 kgkg.. FluiFluidd inclusion inclusionss araree visiblvisiblee iinn somsomee easeastt ooff aa towtownn callecalledd OvallOvallee iinn ChileChile,, neanearr ththee ArgentiniaArgentiniann specimensspecimens.. TemperaturTemperaturee ooff formatioformationn iiss believebelievedd ttoo bebe borderborder;; anandd anotheanotherr reporreportt indicateindicatess thathatt emeraldemeraldss havhavee 300300°° ttoo 450°450°CC witwithh aa pressurpressuree ooff betweebetweenn 22 anandd 3.3.55 kbarkbar.. beebeenn founfoundd iinn ththee AtacamAtacamaa deserdesertt betweebetweenn ththee coascoastt anandd M.O'DM.O'D.. ththee AndesAndes.. UUpp ttoo nonoww thertheree havhavee beebeenn ververyy fefeww ChileaChileann emeraldemeraldss oonn ththee marketmarket.. ThThee emeraldemeraldss havhavee protoproto-- anandd XRXRDD anandd IIRR spectroscopispectroscopicc investigationinvestigationss ooff syngenetisyngeneticc one-one-,, twotwo-- anandd multi-phasmulti-phasee mineraminerall inclusionsinclusions.. TherTheree iiss stronstrongg zonazonall colorationcoloration,, emphasizeemphasizedd undeunderr somsomee Chrysopraseschrysoprases.. crossecrossedd niçoisnicols.. ThThee inclusioninclusionss consisconsistt largellargelyy ooff actinoliteactinolite,, AA.. GAWELGAWEL,, SS.. OLKIEWICOLKIEWICZZ ANANDD WW.. ZABINSKIZABINSKI.. MineralogiaMineralogia dolomitedolomite,, pyrrhotitepyrrhotite,, rutilerutile,, witwithh alsalsoo somsomee bismuthbismuth,, Polonica,Polonica, 28,1997,43-5028, 1997, 43-50.. sulphides, silicates, oxides and phosphates (determined sulphides, silicates, oxides and phosphates (determined ChalcedonChalcedonyy contencontentt ooff somsomee Chrysopraschrysoprasee frofromm by spectroscopy, electron microprobe and an analytical by spectroscopy, electron microprobe and an analytical differendifferentt localitielocalitiess wawass examineexaminedd bbyy XRXRDD anandd IIRR scanninscanningg microscope)microscope).. ThThee ChileaChileann emeraldemeraldss araree spectroscopyspectroscopy.. SampleSampless showeshowedd aa widwidee rangrangee ooff silicsilicaa mineralogically and gemmologically very similar to the mineralogically and gemmologically very similar to the crystallinitycrystallinity.. SpecimenSpecimenss witwithh aa loloww degredegreee ooff silicsilicaa metamorphic emeralds from the Habachtal.E.S. metamorphic emeralds from the Habachta!. E.5. crystallinitcrystallinityy generallgenerallyy havhavee highehigherr NNii contencontentt anandd anan intensintensee greegreenn colourcolour.. SomSomee ooff thesthesee samplesampless alsalsoo gavgavee RadiatioRadiationn damagdamagee iinn zirconszircons.. XRXRDD reflectionreflectionss ooff ththee microcrystallinmicrocrystallinee silicsilicaa phasphasee moganitmoganitee aass welwelll aass aa broabroadd reflectioreflectionn ddhklhkl~ - 1100 ÂA whoswhosee RR.. BIAGINIBIAGINI,, II.. MEMMMEMMII ANANDD FF.. OLMIOLMI.. NeuesNeues JahrbuchJahrbuch fürfUr origioriginn iiss stilstilll unestablishedunestablished.. IInn nonnonee ooff ththee specimenspecimenss MineralogieMineralogie Abhandlungen,Abhandlungen, 6,19976, 1997,257-70., 257-70. examineexaminedd werweree reflectionreflectionss ooff NiNiOO (bunsenite(bunsenite)) presentpresent.. ThThee uraniuuraniumm anandd thoriuthoriumm contencontentt ooff zircozirconn affectaffectss ththee M.O'DM.O'D.. 268209268 degredegreee ooff metamictizatiometamictizationn observedobserved.. UU anandd TThh contentcontentss ooff samplesampless testetestedd rangerangedd frofromm 57-28957-28900 ppppmm anandd LeLess gisementgisementss d'émeraudd'emeraudee dduu BrésilBresil:: genèsgenesee e ett 27-4227-4200 ppppmm respectivelyrespectively.. DensitDensityy decreasedecreasedd iinn paralleparallell typologietypologie.. witwithh UU anandd TThh contencontentt anandd aa rangrangee 4.84.800 >> 4.14.100 g/cmg/ cm33 wawass measuredmeasured.. ChangeChangess iinn X-raX-rayy powdepowderr diffractiodiffractionn werweree alsalsoo GG.. GIULIANIGIULIANI,, AA.. CHEILLETZCHEILLETZ,, J.-LJ.-L.. ZIMMERMANNZIMMERMANN,, A.MA.M.. noticednoticed.. DurinDuringg annealinannealingg thesthesee patternpatternss gavgavee differentdifferent RIBEIRO-ALTHOFFRIBEIRO-ALTHOFF,, CC.. FRANCE-LANORFRANcE-LANORDD ANANDD GG.. FERAUDFERAUD.. resultresultss aass dididd IIRR spectraspectra.. AfteAfterr heatinheatingg aatt 950°C950°C,, X-raX-rayy ChroniqueChronique dede lala rechercherecherche miniere,minière, 526,526, 1997,1997,17-61 17--{51, , illus.illus. diffractiodiffractionn patternpatternss becambecamee sharsharpp anandd showeshowedd aa nearlnearlyy iinn colourcolour,, 99 mapsmaps.. completcompletee structurastructurall recoverrecoveryy whicwhichh waswas,, howeverhowever,, seeseenn ttoo ThThee pre-Cambriapre-Cambriann mineralizatiomineralizationn ooff ththee BraziliaBraziliann bbee incompletincompletee whewhenn comparecomparedd ttoo fullfullyy crystallincrystallinee emeralemeraldd depositdepositss iiss discusseddiscussed.. MaiMainn locationlocationss araree iinn ththee examples.M.O'Dexamples. M.O'D.. statestatess ooff BahiBahiaa (Carnaîb(Carnaibaa anandd Socotö)Socot6),, MinaMinass GéraiGeraiss (Min(Minaa BelmontBelmont,, CapoeiranaCapoeirana)) anandd GoiâGoiass (Sant(Santaa Terezinha)Terezinha).. ThThee depositdepositss araree alwayalwayss locatelocatedd iinn LoweLowerr ProterozoiProterozoicc volcanovolcano­- DossieDossierr centracentrall [o[onn pearls]pearlsl.. sedimentarsedimentaryy sequencesequencess witwithh intercalationintercalationss ooff mafimaficc ttoo JJ.. CASEIROCASEIRO,, J.-PJ.-P.. GAUTHIERGAUTHIER,, JJ.. TABURIAUXTABURIAUX,, GG.. GROSPIRONGROSPIRON,, ultramafiultramaficc rocksrocks.. MineralizatioMineralizationn iiss associateassociatedd eitheeitherr witwithh CC.. LEVI-PLLEVI-PUlÉ ANANDD RP. VERHOEVENVERHOEVEN.. RevueRevue dede gemrnologie,gemmologie, pegmatitepegmatitess intrudinintrudingg mafimaficc ttoo ultramafiultramaficc rockrockss (Socotö(Socot6,, 133,1998,10-22133,1998,10-22,, illusillus.. iinn colourcolour.. CarnaîbaCarnaiba,, BelmontBelmont,, CapoeiranaCapoeirana)) oorr araree linkelinkedd ttoo ductilductilee sheashearr zonezoness affectinaffectingg formatioformationn ooff mafimaficc oorr ultramaficultramafic AA collectiocollectionn ooff shorshortt paperpaperss dealindealingg withwith:: pearlpearlss frofromm rocksrocks.. ThThee originoriginss ooff botbothh typetypess ooff deposidepositt araree describedescribedd TahitiTahiti;; pinctadapinctada margaritifera;margaritifera; trendtrendss anandd developmentdevelopmentss iinn anandd considerablconsiderablee detaidetaill oonn ththee qualitqualityy ooff ththee emeraldemeraldss anandd ththee worlworldd ooff ththee pearlpearl;; ththee possibilitpossibilityy ooff gradingradingg pearlspearls;; theitheirr inclusioninclusionss iiss provided.provided.M.O'D M.O'D.. pearpearll restorationrestoration;; freshwatefreshwaterr pearls.pearls.M.O'D M.O'D..

LLaa foititfoititee delldellee pegmatitpegmatitii ddii SS.. PierPieroo iinn CampoCampo,, RubiesRubies,, sapphiresapphiress anandd emeraldemeraldss -- qualitqualityy anandd IsolIsolaa d'Elbad'Elba.. originorigin.. AA.. GUASTONGUASTONII ANANDD FF.. PEZZOTTAPEZZOTTA.. RivistaRivista mineralogicamineralogica italiana,italiana, A.IA.I.. CASTROCASTRO.. ChristiesChristie's JewelleryJewellery ReviewReview 1997,1997, 19981998,, 26-826-8,, 21,199721,1997,251-5,, 251-5, illusillus.. iinn colourcolour.. illusillus.. iinn colourcolour.. FoititeFoitite,, aa newly-reportenewly-reportedd end-membeend-memberr ooff ththee PropertiesProperties,, valuevaluess anandd outstandinoutstandingg featurefeaturess ooff ththee tourmalintourmalinee group group,, iiss founfoundd iinn ththee SS.. PierPieroo ddii CampCampoo majomajorr gemstonegemstoness araree brieflbrieflyy describeddescribed,, ththee piecpiecee pegmatitepegmatitess oonn ththee IslIslee ooff ElbaElba,, ItalyItaly.. IItt occuroccurss aass fibroufibrouss accompanieaccompaniedd bbyy illustrationillustrationss selecteselectedd frofromm itemitemss recentlrecentlyy crystalscrystals,, anandd detaildetailss ooff somsomee ooff ththee gem-qualitgem-qualityy elbaitelbaitee solsoldd bbyy Christie's.Christie's.M.O' M.O'DD crystalcrystalss araree alsalsoo given.given.M.O'D M.O'D..

JJ.. Gemm.,Gemm., 1998,26,4,1998, 26, 4, 266-272 Über die Bildung von Perlmutter und Perlen. Gem news - the 26th International Gemmological Conference. H.A. HÄNNI. Gemmologie (Zeitschrift der Deutschen Gemmologischen Gesellschaft), 46, 1997, 183-96, M.L. JOHNSON AND J.I. KOIVULA. Gems & Gemology, 33(4), 7 photographs, 3 diagrams, bibl. 1997, 298-310,15 illus. in colour. The Renishaw Micro-Raman spectroscopy system The author reviews various papers dealing with nacre with a near infrared system has helped to separate amber and pearls and compares these notes to his own from its various imitations. Kauri gem from New Zealand observations. Nacre and pearls are formed in the same may be labelled amber if older than Middle Tertiary way, the outer mantle epithelium first producing the otherwise younger material should be called copal. periostracum, then columnar and finally tabular calcium Fluorescence zoning in amber is associated with fauna carbonate (nacre). The same sequence produces natural inclusions and is diagnostic for natural amber. Three new pearls from the centre to the rim of the pearl. The chrysoberyl deposits were discovered in 1996 near the transplantation of an epithelium graft to an organ in the east coast of India, although separated by hundreds of shell means that a 'microchip' brings the knowledge of kilometres they were probably formed at the same nacre forming to a part of the animal with no tradition of geological time. Bactrian emeralds are now thought to pearl forming and the graft grows into an entire pearl sac. have come from Bactria (Northern Afghanistan) on the The article ends with a short survey of the properties of basis of new deposits of emeralds found in the Panjshir natural, cultured and imitation pearls.E.S. valley The country of origin of emeralds, especially Colombian emeralds, may be determined by the isotopic Quartz-Mineralisationen in Rhyolithkugeln nahe composition of oxygen of the various rock types and the des Seebachsfelsens südwestlich Friedrichroda, emeralds found in association with these rocks. Emeralds Thüringer Wald. used by the ancient Romans were probably mined in Upper Egypt. G. HOLZHEY. Gemmologie (Zeitschrift der Deutschen Blue quartz from Madagascar was found to contain Gemmologischen Gesellschaft), 46, 1997, 197-212, 16 many species of inclusion; lazulite inclusions were signif­ photographs, 2 maps, 1 table, bibl. icant and imparted the overall blue colour to the quartz. Globular rhyolites (spherulites) contain in central star- Ornamental and gem stones from Bolivia are discussed shaped cavities epigenetic jasper-like minerals, agates and with regard to their location, size and economics. Good macrocrystalline quartzes such as rock crystal and quality cultured pearls from Indonesia are produced from amethyst as well as calcite and fluorite. The agates, blister pearls grown in the mollusc Pinctada maxima; including the dominant horizontal granular type agate are recently resin has been used as the bead nuclei in some 209269 characterized by differences in genetic attributes. Layers pearls so that they resemble artificial pearls with a low SG of granular type are followed by layers of increasingly and a deceptive sheen caused by a thin nacreous layer. crystalline grained structure, followed by layers showing Several new sapphire deposits have been found in macrocrystalline quartz.E.S. Madagascar especially in the north. The Tunduru-Songea HET KASTEEL gem field in southern Tanzania produces many different varieties of gemstone such as corundum, spinel, garnet, Some new unusual cat's-eyes. quartz, beryl, tourmaline, kyanite, diamond, etc.J.J. J. HYRSL. Canadian Gemmologist, 18, 1997, 105-6, illus. in black-and-white. Pearl identification.

Some rare chatoyant gem materials recently reported S.J. KENNEDY. Australian Gemmologist, 20(1), 1998, 2-19, 48 include yellow baryte from the Czech Republic, brazil- black-and-white illustrations and 1 in colour, 1 graph. ianite, dark blue translucent kyanite from India, red to Commencing with the description of a new X-ray dark red Tasmanian crocoite, bluish danburite from Alto unit, designed as a replacement for the original unit in the Chapare area of Bolivia and from Madagascar, light Gem Testing Laboratory's London premises, this review brown enstatite from Tanzania, rhodochrosite from a new of pearl identification covers their mode of formation and locality in Kazakhstan and opaque, brownish-black rutile the various techniques employed to test both individual from SrHETi Lanka.M.O'DKASTEEL. pearls and pearl necklaces. The use of X-ray techniques to test pearls is discussed as well as the visual features which allow pearls to be categorized. 'Keshi cultured pearls', Darwin-Glas: ein schleifwürdiger, grüner Tektit. natural blister pearls, imitation pearls and the treatment SR.-A. JACOBS. Gemmologie (Zeitschrift der Deutschen of pearls are also covered. The differentiation of natural Gemmologischen Gesellschaft), 46(1), 1997, 7-12. pearls from non-nucleated cultured pearls is considered to be the biggest challenge facing the pearl tester. RG.R. Tektites of gem quality have been recovered from the area of Mount Darwin, Tasmania, and have been found to Pearls and pearl oysters in the Gulf of be compositionally similar to moldavites from Bohemia. They arise from an impact event and are mostly pale to dark California, Mexico. green with a few greenish-brown and black specimens. The D. MCLAURIN, E. ARIZMENDI, S. FARELL AND M. NAVA. RI range is 1.470-1.482 and SG is 2.26. Swirl marks and gas Australian Gemmologist, 19(12), 1997, 497-501, 6 illus. bubbles are found as inclusions.M.O'D. in colour, 1 map.

Abstracts - Gems and Minerals For more than four centuries until overfishing caused 1859. Some outstanding specimens are illustrated with a their demise, pearl fisheries in the Gulf of California were brief biography. The Princess played a conspicuous part the main source of natural coloured pearls. Now a pilot- in HETthe RevolutioKASTEELn of 1762.M.O'D. scale commercial venture has been set up by I.T.E.S.M.- Perlas de Guaymas for culturing the native pearl oysters Titanite und seine Einschlüsse. Pteria sterna and Pinctada mazatlanica, and their pearls. The pearl farm is located at Bacochibampo Bay, Guaymas, G. NIEDERMAYR. Mineralien Welt, 9(1), 1998,15-16, illus. in Sonora, Mexico, and uses the suspended culture system colour. and the Mexican grafting technology developed by Titanite (sphene) has been found to contain a number I.T.E.S.M. Around 150,000 pearl oysters were cultured of fluid inclusion patterns which are described and from both the above species, and in 1997 produced 30,000 illustrated from specimens originating from Austria and mabe pearls and some round pearls.P.G.R. Brazil.M.O'DHET KASTEEL.

What's new in minerals. Business review: gemstones. T. MOORE. Mineralogical Record, 28, 1997, 505-8 illus. in M. O'DONOGHUE. Britannica Book of the Year 98,1998,164. colour. Reviews new gem species and varieties, stones Gem-quality yellow prisms of the rare mineral returning to the market after long periods of absence, sturmanite are reported from the Springfield, Massachusetts developments in gemstone commerce and the saleroom Mineral Show, 1997. Other species of interest and of gem with details of particularly important prices paid. Reports quality include sea-green fluorite octahedra from the Wise on the use of child labour in the Indian diamond trade are mine, Westmoreland, New Hampshire (once more being noted and the economic financial situation in some Asian worked for specimens), orange transparent baryte from the countries is reviewed as it affects gemstone prices. Rosh Pinah mine in southern Namibia and crystals of pale (Author's abstract) M.O'D. brown transparent axinite from Khapalu, Ghanche District, Baltistan, Pakistan.M.O'D. HET KASTEEL Le contrôle des perles à partir de 1929 au Gem Trade Lab notes. Laboratoire Gemmologique Français (du T.H. MOSES, I.M. REINITZ, AND S.F. MCCLURE. Gems & laboratoire syndical au laboratoire CCIP). Gemology, 33(4), 1997, 292-6, 7 illus. in colour. J.-P. POIROT AND E. GONTHIER. Revue de gemmologie, 133, 272090 A green aquamarine showed an unusual absorption 1998, 26-7, illus. in colour. band at 537 nm in addition to the bands at 427 and History of the part played by the Laboratoire 456 nm, this line is typical of untreated aquamarines and Gemmologique Français in pearl testing since 1929 with is found in yellow and colourless beryls. A violetish-blue details of some of the instruments and tests used. cushion-shaped stone thought to be tanzanite was found M.O'D. to be beryl and it was strongly pleochroic with six sharp closely spaced lines between 575 and 690 nm. The colour in these stones is not stable and liable to fade. Using a Türkis aus Thüringen und Sachsen. Raman spectrometer and EDXRF a large dark red H. RIEDEL, G. HOLZHEY, S. PESTEL AND S. WEISS. Lapis, 23(2), cabochon was found to be a pyrope-almandine garnet and 1998, 42-4, illus. in colour, 1 map. not highly refractive HETglass.J.JKASTEEL. Turquoise of ornamental quality is reported from Weckersdorf, Thuringia, Germany, where it occurs in a Chrysoprase from Warrawanda, Western Australia. siliceous schist with iron hydroxides and translucent

T. NAGASE, M. AKIZUKI, M. ONODA AND M. SATO. Neues crystals of yellow baryte. Turquoise is also described from Jahrbuch für Mineralogie, Monatshefte, 1997(7), 289-300. Chrieschwitz near Plauen in the Vogtland area of Saxony. A study of Chrysoprase from the boundary between Some of this material may also be of fashioning quality. granite and serpentinite in the Warrawanda district, M.O'D. 80 km SW of Newman, Western Australia, is reported using EM, TEM, FTIR and EPMA techniques. Inclusions Green vanadium-bearing titanite from of a cotton-like aggregate of kerolite were found as Chibougamau, Quebec, Canada. extremely fine-grained crystals; the kerolite contains G. ROBINSON AND W WIGHT. Gemmologie (Zeitschrift der -10 wt.% NiO, the NiO content increasing with the Deutschen Gemmologischen Gesellschaft), 46, 1997, degree of silicification of the surrounding serpentinite. It 225-8,1 photograph, 2 tables, bibl. is inferred that this Ni-bearing kerolite is the cause of the apple-green colour of the Chrysoprase.R.A.H. Gem-quality emerald-green titanite (sphene) has been found at the Lemoine vanadium mine near Chibougama, Quebec, where it occurs in alpine-type hydro thermal Gems from the collection of Princess Dashkov. veins in magnetite and gabbro. RI 1.90-1.99, SG 3.519. O. YA NEVEROV. World of Stones, 12, 1997, 39^1, illus. in Because chromium is present only in trace amounts, colour. vanadium seems to be the principal chromophore; Engraved gems form part of the collection of Princess vanadium causing emerald-green colour in titanite has Catherine Dashkov, whose Memoirs were published in not previously been reported.E.S.

/. Gemm., 1998, 26, 4, 266-272 HistorieHistorie,, GeologieGeologie unundd MineralogiMineralogiee dederr QuarzQuarz­- What'What'ss newnew inin minerals.minerals. KristalleKristalle vonvon HerkimerHerkimer,, NewNew YorkYork.. [VARIOUS[VARIOUS AUTHORS.]AUTHORS.] Mineralogical Record, 28(5)28(5),, 1997,1997, R.HR.H.. RussRuss.. Mineralien Welt, 8(6),8(6), 1997,1997, 61-71,61-71, illusillus.. inin 409-17409-17,, illusillus.. inin colour.colour. colour,colour, 2 maps.maps. AmonAmongg gemgem mineralmineralss displayedisplayedd atat recenrecentt showshowss werewere RocRockk crystalcrystal quartquartzz frofromm thethe HerkimeHerkimer'r 'diamonddiamond' ' minemine largelarge greegreenn ChineseChinese fluoritefluoritess fromfrom thethe ZianghualiZianghualinn mine,mine, iinn ththee UppeUpperr CambrianCambrian atat MiddlevilleMiddleville,, north-wesnorth-westt ooff Hunan,Hunan, andand largelarge rutilrutilee crystalcrystalss frofromm ththee classiclassicc sitsitee atat Albany,Albany, NeNeww YorkYork,, iiss famousfamous foforr ititss perfectioperfectionn ofof form.form. GravesGraves Mountain,Mountain, Georgia,Georgia, USAUSA.. TheThe ChinesChinesee fluoritesfluorites CrystalsCrystals tootookk theitheirr varietavarietall namnamee fromfrom NicholaNicholass HerkimerHerkimer areare reportereportedd frofromm mormoree thanthan oneone shoshoww iinn ththee UnitedUnited (1728-1777),(1728-1777), frofromm a familyfamily ofof GermaGermann originorigin.. TheyThey occuroccur atat StatesStates.. TanzaniteTanzanite crystalcrystalss areare stilstilll onon thethe market;market; ononee finefine differentdifferent levellevelss inin ththee minminee andand mamayy shoshoww phantophantomm effectseffects specimenspecimen wawass nearlnearlyy 3 cmcm long.long. TheThe areareaa ofof XuXu BaBaoo Diang,Diang, oror sceptresceptre formsforms.. SomeSome specimensspecimens ooff particulaparticularr claritclarityy havehave PiugwuPiugwu,, Sichuan,Sichuan, China,China, isis knownknown foforr finfinee specimenspecimenss ooff traditionalltraditionallyy beebeenn callecalledd HerkimeHerkimerr diamonds.diamonds.M.O'D M.O'D.. cassiteritecassiterite.. ItIt isis associateassociatedd withwith crystalscrystals ooff colourlescolourlesss berylberyl ttoo makmakee attractivattractivee groups.groups. CrystalsCrystals ooff rubrubyy oonn calcitecalcite matrixmatrix,, somsomee withwith a finefine raspberry-redraspberry-red colourcolour,, andand BitterfeldeBiUerfelderr BernsteinBernstein:: derder SchatzSchatz ausaus dederr measurinmeasuringg uupp ttoo 5 cmcm,, havhavee beebeenn foundfound atat ththee LuLucc YeYenn 'Goitsche'.'Goitsche'. rubrubyy minminee inin VietnaVietnamm anandd featuredfeatured iinn thethe ParisParis showshow.. FineFine S.S. SCHELLHORN.SCHELLHORN. Lapis, 23(3)23(3),1998,35-7,, 1998, 35-7, Illus.Illus. inin colour.colour. reddisreddishh crystalscrystals ooff grossulargrossular frofromm SierrSierraa dede laslas Cruces,Cruces, ShortShort historyhistory ofof ththee ambeamberr findsfinds,, estimatedestimated aatt approxi­approxi­ Coahuila,Coahuila, MexicoMexico,, measuremeasuredd uupp toto 2.82.8 cmcm anandd beautifulbeautiful matelymately 2222 milliomillionn yearsyears oldold,, inin thethe BitterfeldBitterfeld regioregionn ofof centralcentral crystalcrystalss ofof amethysamethystt andand smoksmokyy quartzquartz uupp ttoo 12.712.7 ccmm werewere GermanyGermany.. TheThe actualactual amber-producinamber-producingg areaarea,, knowknownn locallylocally showshownn fromfrom ththee PhilliPhilliss AnAnnn claim,claim, LakeLake George,George, Colorado. The same locality produces twins of purple asas Goitsche,Goitsche, containcontainss brown-coabrown-coall recoverrecoveryy sites,sites, somesome Colorado. The same locality produces twins of purple fluorite.M.O'D. floodedflooded,, whichwhich havehave beenbeen illegallyillegally raideraidedd foforr amberamber speci­speci­ fluorite. M.O'D. mensmens.. SomeSome insecinsectt inclusionsinclusions havhavee beebeenn reportedreported.. M.O'D.M.O'D. What'sWhat's neneww iinn mineralsminerals.. DiDiee TucsonTucson ShoShoww 1998.1998. [VARIOUS[VARIOUS AUTHORS.]AUTHORS.] Mineralogical Record, 29,29,1998,125-41 1998, 125-41,, J.J. ScOVILSCOVIL ANANDD B.B. LEESLEES.. Lapis, 23(4)23(4),, 1998,1998, 35-835-8,, illusillus.. inin illus.illus. iinn colour.colour. colourcolour.. DifferenDifferentt correspondentscorrespondents describdescribee mineraminerall specimensspecimens AmonAmongg gem-qualitygem-quality mineralsminerals appearingappearing aatt ththee 19981998 seenseen atat a numbenumberr ofof gegemm anandd mineraminerall showshowss duringduring 19971997 TucsoTucsonn ShowShow werweree finfinee crystalcrystalss ooff amazoniteamazonite frofromm TreeTree allall inin thethe UniteUnitedd StatesStates exceptexcept foforr thethe MiinchenMünchen RooRoott PocketPocket,, Pike'sPike's Peak,Peak, ColoradoColorado,, USAUSA,, wherwheree itit occursoccurs MineralientageMineralientage.. AmongAmong ththee specimensspecimens ofof gegemm qualitqualityy areare 209271271 iinn a pegmatitpegmatitee witwithh smokysmoky quartzquartz.. FineFine blubluee aquamarineaquamarine amazoniteamazonite andand smokysmoky quartzquartz fromfrom ththee classicclassic localitylocality atat crystalcrystalss fromfrom ththee ThuonThuongg XiaXiann districtdistrict,, HoHoaa Province,Province, Pike'Pike'ss PeakPeak,, Colorado,Colorado, pinpinkk fluoritefluorite octahedroctahedraa frofromm thethe VietnamVietnam,, werweree alsalsoo onon display.display.M.O'D M.O'D.. ChamoniChamonixx areareaa ooff ththee FrencFrenchh Alps,Alps, yellow-brownyellow-brown sphenesphene crystalscrystals frofromm AlchuriAlchuri,, BaltistanBaltistan,, PakistanPakistan,, emeraldemerald crystals from the Brumado mine, Bahia, Brazil, and from crystals from the Brumado mine, Bahia, Brazil, and from A newnew eraera forfor opalopal nomenclature.nomenclature. the Medina mine, Minas Gerais, Brazil. the Medina mine, Minas Gérais, Brazil. A.A. SMALLWOODSMALLWOOD.. Australian Gemmologist, 19(12),19(12), 1997,1997, The feature also describes the newly-opened mineral 486-96,486-96, 2626 illusillus.. iinn colour.colour. The feature also describes the newly-opened mineral hallhall atat ththee NationaNationall MuseuMuseumm ooff NaturaNaturall History,History, A neneww opaopall nomenclaturenomenclature,, formulatedformulated bbyy ththee GAAGAA SmithsonianSmithsonian Institution,Institution, WashingtoWashingtonn DC,DC, USAUSA.. M.O'D.M.O'D. OpalOpal NomenclaturNomenclaturee Sub-committee,Sub-committee, iiss designeddesigned foforr useuse throughoutthroughout thethe gemstonegemstone andand jewellerjewelleryy industryindustry,, nonott onlyonly inin AustraliAustraliaa bubutt internationally.internationally. Synthetics and Simulants UndeUnderr ththee categorycategory 'Type'Typess ooff naturanaturall opal',opal', threethree formsforms ofof naturanaturall opaopall araree listedlisted whichwhich aparapartt fromfrom beingbeing GeGemm newsnews - ththee 26th26th InternationalInternational GemmologicalGemmological cucutt anandd polishepolishedd areare otherwiseotherwise untreated untreated.. TheseThese typestypes includeinclude opalopal havinhavingg a substantiallsubstantiallyy homogeneoushomogeneous Conference.Conference. chemicachemicall compositioncomposition,, bouldeboulderr opaopall andand matrixmatrix opal.opal. M.L.M.L. JOHNSONJOHNSON ANANDD J.LJ.I. KOIVULAKOIVULA.. Gems & Gemology, 33(4)33(4),, TheThe nexnextt categorycategory,, 'Varieties'Varieties ofof naturalnatural opal',opal', describesdescribes 1997,298-310,151997,298-310,15 illus.illus. inin colour.colour. ththee gem'sgem's bodbodyy tontonee (i.e.(i.e. ititss face-upface-up relativrelativee darknessdarkness oror (Further(Further summariessummaries ofof paperpaperss givegivenn atat thethe 26th26th IGCIGC lightness,lightness, ignorinignoringg play-of-colourplay-of-colour)) andand itsits transparency.transparency. covercover a rangrangee ofof topics.topics.)) 8080%% ofof imitatioimitationn pearlspearls BodyBody tonestones NNll ttoo NN44 areare usedused foforr blacblackk opal,opal, NN55 anandd N6N6 manufacturemanufacturedd inin JapanJapan ususee plastiplasticc beabeadd centres,centres, whilewhile foforr dardarkk opalopal,, anandd NN77 ttoo NN99 foforr lightlight opal.opal. AAnn opalopal witwithh a otheotherr imitatioimitationn pearlpearlss havhavee shelshelll oorr whitwhitee alabastealabasterr glassglass distinctldistinctlyy colourecolouredd bodbodyy hahass a huhuee notationotationn appendeappendedd toto foforr ththee centracentrall beadbead.. GrowthGrowth induceinducedd imperfectionimperfectionss andand ititss bodbodyy tontonee classification.classification. TransparencTransparencyy codescodes AA,, BandB and inhomogeneitieinhomogeneitiess iinn crystalcrystalss araree importanimportantt especiallespeciallyy iinn thethe C areare usedused toto covercover allall formsforms ofof diaphaneitydiaphaneity rangingranging fromfrom identificatioidentificationn ofof synthetisyntheticc material.material. RecenRecentt researchresearch intointo transparentransparentt toto opaque.opaque. syntheticsynthetic quartquartzz growgrownn iinn sodiumsodium hydroxidhydroxidee solutionssolutions AlthougAlthoughh notnot associateassociatedd withwith thethe descriptivedescriptive showsshows variationsvariations inin morphologmorphologyy witwithh anan increasincreasee inin classificationsclassifications foforr naturanaturall opals,opals, ththee nomenclaturenomenclature alsoalso temperaturetemperature.. ThreThreee piecepiecess ofof a transparenttransparent purplish-pinkpurplish-pink discussediscussess opalopal treatmentstreatments,, compositecomposite naturanaturall opal,opal, materiamateriall werewere founfoundd ttoo bbee neodymiuneodymiumm penta-phosphatepenta-phosphate synthetisyntheticc opaopall andand imitatioimitationn opal.opal.P.G.R P.G.R.. (NdP(NdPP14)'5014).

Abstracts - Synthetics and SimulantsSimulants TitaniuTitaniumm anandd chromiuchromiumm diffusion-inducediffusion-inducedd starstar gemmologicagemmologicall methods.. DiagnostiDiagnosticc microscopimicroscopicc featuresfeatures sapphiresapphiress cacann bbee identifieidentifiedd bbyy characteristicharacteristicc colourcolour werweree observeobservedd iinn ththee stonstonee whicwhichh includeincludedd naturanaturall oorr zoningzoning,, absorptioabsorptionn spectrspectraa togethetogetherr witwithh a reredd halhaloo oonn ththee synthetisyntheticc beryberyll seedseedss togethetogetherr witwithh characteristicharacteristicc growthgrowth surfacsurfacee anandd a highighh relierelieff reredd outlinoutlinee whewhenn immerseimmersedd iinn zoningzoning., usuallusualJyy associateassociatedd witwithh coloucolourr zoningzoning., paralleparalJell ttoo methylenmethylenee iodide.HETiodide.J.J KASTEELJ.J.. ththee seedseed.. ThThee zoninzoningg formeformedd aatt aann anglanglee ooff betweebetweenn 20°° anandd 4040°° ttoo ththee c-axic-axiss ooff ththee synthetisyntheticc emeralemeraldd anandd aass noo crystacrystall facefacess iinn naturanaturall emeralemeraldd araree founfoundd withiwithinn thithiss LaLabb notes.notes. rangrangee iitt iiss aann importanimportantt diagnostidiagnosticc featurefeature.. SpiculesSpicules TT.. MOSESMOSES,, Il.. REINITREINITZZ ANANDD S.FS.P.. MCCLURE.. Gems & Gemology, orientateorientatedd paralleparallell ttoo ththee c-axic-axiss werweree commonlycommonly 33(4)33(4),1997,292-6,7, 1997, 292-6, 7 illusillus.. iinn colour.colour. associateassociatedd witwithh tintinyy crystalcrystalss ooff chrysoberychrysoberyll oorr A paipairr ooff sunglassesunglassess madmadee foforr EltoEltonn JohJohnn hahadd lenseslenses occasionalloccasionallyy berylberyl.. AlsAlsoo typicatypicall werweree needlneedle-like-likee madmadee frofromm synthetisyntheticc sapphire.sapphire.J.J J.J.. inclusioninclusionss whicwhichh werweree founfoundd orientateorientatedd almostalmost perpendiculaperpendicularr ttoo ththee seeseedd oonn dominandominantt growtgrowthh facesfaces.. EDXRF analysis and infrared spectroscopy showed SynthetiSyntheticc moissanitemoissanite:: a neneww diamondiamondd substitutesubstitute.. EDXRF analysis and infrared spectroscopy showed chlorinchlorinee tto bbee a diagnosticdiagnostic elemenelementt givingivingg risrisee ttoo a serieseriess -1 KK.. NASSAUNASSAU,, S.FS.P.. MCCLURE, SS.. ELEN ANANDD J.E.. SHIGLEYSHIGLEY.. Gems & ooff absorptioabsorptionn bandbandss iinn ththee 2500-3102500-31000 cmem-! region,, whicwhichh Gemology,Gemology, 33(4), 1997, 260-75,1260-75, 199 illus.. iinn coloucolourr anandd 22 araree nonott seeseenn iinn naturanaturall emeraldsemeralds.. ThThee stonestoness examineexaminedd diddid tablestables.. nonott shoshoww ananyy detectabledetectable ironiron,, bubutt thithiss iiss similasimilarr ttoo certaincertain A neneww diamondiamondd substitutsubstitutee iiss synthetisynthetiCc moissanitemoissanite,, aa naturanaturall emeraldsemeralds.. AlsAlsoo iitt wawass founfoundd thathatt ththee RRII anandd SGSG silicosiliconn carbidcarbidee (SiC)(SiC),, anandd hahass onlonlyy recentlrecentlyy beenbeen valuevaluess ooff ththee synthetisyntheticc stonestoness overlappeoverlappedd thosthosee ooff lowlow manufacturemanufacturedd aass a neanearr colourlescolourlesss materialmaterial.. ThThee GIAGIA alkalalkalii naturanaturall emeralds.emeralds.J.J J.).. examineexaminedd 2233 samplesampless ooff neanearr colourlescolourlesss ttoo lighlightt yellow,yellow, greegreenn anandd gregreyy stones,stones, bubutt alalll appeareappearedd colourlescolourlesss whenwhen vieweviewedd facfacee upup.. AlthougAlthoughh thertheree iiss nnoo simplsimplee testestt ttoo 174and identifidentifyy moissanitmoissanitee conclusivelyconclusively,, thertheree araree manmanyy testtestss thatthat wilwilll provprovee iitt iiss nonott diamonddiamond.. MoissanitMoissanitee iiss slightlslightlyy lessless ThThee HodgkinsoHodgkinsonn methodmethod,, a.k.aa.k.a.. ththee eyeyee anandd brillianbrilliantt thathann diamond,, showshowss mormoree dispersiodispersionn anandd iiss prisprismm methodmethod:: somsomee furthefurtherr adaptionsadaptions.. doublydoubly refractivrefractivee witwithh a birefringencbirefringencee ofof 0.043, whicwhichh iiss mosmostt readily seenseen whewhenn vieweviewedd througthroughh ththee girdlegirdle aass allal l D.BD.B.. HOOVERHOOVER.. Australian GemmologistGemmologist,, 20(1)200), 1998, 20-33,, 5 ththee sstonetones examinedexamined werweree cutcut witwithh theitheirr c-axisc-axis diagrams,diagrams, 4 graphs, 3 tables.tables. 209272 perpendiculaperpendicularr ttoo ththee tabltablee facetfacet.. MoissanitMoissanitee showsshows nonenone ooff TheThe HodgkinsoHodgkinsonn method,, whicwhichh useusess onlyonly ththee humanhuman 272 ththee strainstrain fracturefracturess andand inclusiinclusiononss associatedassociated withwith eyeeye andand a distantdistant lightlight source,source, permitpermitss thethe identificidentificatioationn ooff diamonds,diamonds, bubutt insteadinstead therethere areare whitwhitee linlinee inclusionsinclusions manmanyy gemstonesgemstones bbyy enaenablinblingg theitheirr refractiverefractive indices,indices, paralleparallell ttoo ththee c-axis.c-axis. Moissanite hass anan SGSG ofof 3.20-3.243.20-3.24 absorptionabsorption spectra,spectra, dispersiondispersion andand birefringencbirefringence-toe-to­- 1 (diamond(diamond 3.52)3.52) andand a hardnesshardness ofof 9!//,4.. ProblemProblemss dodo occuroccur dispersiondispersion ratiratioo to bbee estimated.estimated. TheThe fundamentalfundamentalss ofof thisthis whewhenn a thermathermall probeprobe isis usedused asas diamonddiamond andand moissanitemoissanite methodmethod areare reviewed,reviewed, anan alternativealternative technique foforr havhavee overlappingoverlapping thermalthermal inertialinertial rangrangeess andand furtherfurther teststests estimatingestimating rrefractivefractive indindeexx explained,explained, andand thethe methomethodd ooff mustmust bbee useusedd ttoo separateseparate thesthesee stones.stones.J.J J.J.. quantifyingquantifying thethe birbirefringence-to-dispersioefringence-to-dispersionn ratiratioo foforr identificatioidentificationn purposespurposes described.described.P.G.R P.G.R.. CharacterizationCharacterization ofof ChineseChinese hydrothermalhydrothermal syntheticsynthetic emerald.emerald. KristalleKristalle unundd LichtLicht.. K.K. ScHMETZER,SCHMETZER, L.L. KIEFERTKlEFERT,, H.-J.H.-J . BERNHARDBERNHARDTT ANDAND Z.Z. BEIu.BEILI. O.O. MEDENBACH,MEDENBACH, P.w.P.W. MIRWALDMIRWALD ANDAND P.P. KUBKUBATHATH.. Mineralien Gems & GemologyGemology,, 33(4),, 1997,1997, 276-91, 2020 i1lusillus. iinn WeltWelt,, 9(2),1998,, 1998,17-3217-32, lIluIlluss.. inin colourcolour. cocoloulourr andand 3 tables.tables. DespiteDespite ththee title,title, thethe articlearticle illustratesillustrates andand describesdescribes a IInn 19931993 hydrothermalhydrothermal syntheticsynthetic emeraldsemeralds mademade bbyy numbernumber ofof opticaloptical instrumentsinstruments usedused forfor minermineraall ProfessorProfessor ZengZeng Jiliang,Jiliang, China,China, becamebecame commerciallycommercially identificationidentification.. Microscopes,Microscopes, producersproducers ofof polarizedpolarized light,light, available.available. TheseThese emeraldsemeralds werewere growngrown inin anan alkali-freealkali-free goniometers, universaluniversal stagesstages andand instrumentsinstruments foforr chlorine-bearingchlorine-bearing solutionsolution atat muchmuch higherhigher pressurespressures thanthan obtainingobtaining refractiverefractive indexindex areare presentedpresented withwith briefbrief normallynormally associatedassociated withwith syntheticsynthetic emeralds.emeralds. TheThe authorsauthors biographicalbiographical notesnotes ofof pioneerspioneers inin mineralogicalmineralogical examinedexamined 1111 stonesstones andand testedtested ththeemm byby standardstandard instrumentationinstrumentation.M.O'D. M.O'D..

]./. Gemm., 1998,26,4,266-2721998,26, 4, 266-272 BOOK REVIEWS

Famous diamonds. [Third edition] English regalia of 1897. It seems then to have been copied by many later authorities. However, both Dieulafait in I. BALFOUR, 1997. Christie's, London, pp 320, 150 colour 1871 and Professor Church in 1882 give a weight of 102 and 70 black-and-white illustrations. Hardback and 3/ ct. This converts to 105.53 metric carats, extremely DW £65.00. ISBN 0 903432 56 X. 4 close to the actual weight. Although this is the third edition of Famous diamonds, it is on an altogether more lavish scale than its predecessors. It An absolutely fascinating appendix is included which has a slightly larger format, is on better quality paper, and reproduces, over five pages, Asscher's step-by-step diary much new information has been added on important of their cutting of the Cullinan between February and stones, including stones auctioned up to 1997. October 1908. The book starts with a most informative general There is a useful bibliography of two pages with some introduction to diamonds, detailing their history, sources, interesting items, although it should really be headed 'A mining, trade cutting and use. The mention of their selected bibliography' because the literature on diamonds is properties of brilliance and fire is unfortunately so brief as now immense. It is satisfying to find that the book ends with to be, perhaps, unhelpful to those not already familiar a good index, the lack of which has ruined many an other­ with these properties. wise good publication. This is, perhaps, the place to plead with publishers to revert to the old custom of binding in a There are then 76 separate chapters dealing bookmark (or even two). This greatly facilitates looking up alphabetically with individual major stones, most in items that have more than one reference in indexes. impressive detail including descriptions of the stones themselves, their history and often details of associated This is a most desirable book, full of useful and and similar material. Some of these chapters, particularly fascinating information, beautifully produced at a price that on the Hope, have been significantly expanded from which, by current standards, is quite reasonable. It should the previous edition. These are followed by a chapter have wide appeal to both jewellery and other historians, devoted, again alphabetically, to describing more briefly a as well as to a large spread of general readers.N.B.I. 209273 further 40 'notable' stones. In many cases, due to their value, the ownership of such Identifying gems and precious stones stones is extremely closely guarded, and it is very difficult C. HALL, 1997. Apple Press, London, pp 80, illustrated in to acquire accurate knowledge about them. Ian Balfour, who colour, hardcover. £5.99. ISBN 0 85076 426 3. spent many years in the diamond business, has been Reprint of an excellent short guide first published in granted unprecedented access to many of these stones and 1993 by Quintet Publishing Ltd. The major gem species their associated archival material. He has gathered together are described with notes on properties neatly set out in this book a vast amount of information on major diagrammatically and in colour.M.O'D. diamonds that is simply not available elsewhere. A table is included towards the end of the book listing the 89 diamonds of over 100 carats known up to 1997. Diamonds Collecting and classifying coloured diamonds: are not easy to photograph well, and the producers of this an illustrated history of the Aurora collection. book are to be congratulated on the generally fine illustra­ S.C. HOFER, 1998. Ashland Press Inc., New York, USA tions throughout. (distributed in the UK by CRU Publishing Ltd., There is a section of three pages on fancy coloured London), pp xxi, 742, illus. in colour. Hardcover diamonds and the causes of their colour. This has been ISBN 0 9659410 1 9. £197.00. written by Eric Emms, FGA, DGA, who has handled a This very large and heavy book is a celebration of the difficult subject very well in such a small space. 260 polished coloured diamond specimens at present on A column is included on the carat weight and the display at the American Museum of Natural History, New confusion that can occur from the difference between York. The collection is catalogued, described and various old carats and the modern metric carat (0.2 gram). illustrated at the beginning of the book, which continues It is unfortunate that, as an example of such confusion, the with an account of the world of coloured diamonds, Koh-i-Noor is used. The previously much quoted weight including a lengthy examination of the cause and of the Koh-i-Noor (after re-cutting in 1852) as 108.93 ct, perception of colour. Chapters deal with the collecting of rather than the recently authenticated weight of coloured diamonds, natural supply and human demand 105.60 metric ct, seems, in fact, to have arisen from faulty and the conception of rarity, buying and selling, colour research by authors rather than from any confusion over perception and colour grading, how face-up colour can be the unit of weight (108.93 metric carats converts to 106 Vie- defined, coloured diamond classification and the old English carats). This incorrect weight is reported in terminologies used. Appendices include a cut and colour several nineteenth-century books including Davenport's compendium, a glossary and a bibliography.

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 ThThee boobookk iiss beautifullbeautifullyy produceproducedd anandd thertheree iiss nnoo AfteAfterr a survesurveyy ooff whawhatt jewellerjewelleryy meanmeanss iinn ththee contexcontextt doubdoubtt thathatt seriouseriouss collectorcollectorss wilwilll wanwantt ttoo bubuyy itit,, whethewhetherr oorr ooff RomaRomann BritainBritain,, ththee boobookk considerconsiderss somsomee ooff ththee nonott thetheyy alsalsoo colleccollectt colourecolounedd diamondsdiamonds.. ThThee standarstandardd ooff evidencevidencee witwithh aann examinatioexaminationn ooff hoardhoardss anandd ooff ththee photographphotographyy iiss state-of-the-arstate-of-the-artt anandd ththee hundredhundredss ooff illustra­illustra­ generagenerall archaeologicaarchaeologicall contextcontext.. ThThee twtwoo cultures,, CeltiCelticc tiontionss gaigainn a greagreatt deadeall bbyy beinbeingg kepkeptt small.. MounteMountedd stonesstones anandd Graeco-RomaGraeco-Romann (i.e(i.e.. nativnativee anandd importedimported)) broughbroughtt araree ssoo ofteoftenn chosechosenn ttoo illustratillustratee bookbookss oonn gemstonegemstoness thathatt ththee togethetogetherr distincdistinctt typetypess ooff ornamenornamentt anandd ththee designsdesigns,, readereaderr cannocannott seseee ververyy mucmuchh ooff individuaindividuall diamonddiamondss andand metalmetalss anandd workmanshiworkmanshipp ooff ththee twtwoo areaareass makmakee uupp mosmostt whewhenn colourecolouredd diamonddiamondss araree featurefeaturedd iitt iiss mucmuchh bettebetterr ttoo ooff ththee followinfollowingg texttext.. grougroupp loosloosee polishepolishedd exampleexampless togethertogether,, sometimesometimess withwith MateriaMateriall iiss considereconsideredd undeunderr ththee headingheadingss fjngfingerer­- severaseverall everydaeverydayy colourecolouredd objectobjectss foforr comparisocomparisonn anandd thithiss iiss ringsrings,, gemstonegemstoness anandd otheotherr settingssettings,, necklacenecklacess andand whawhatt hahass beebeenn dondonee herehere.. OpeninOpeningg ththee pagespages,, witwithh ththee textextt braceletsbracelets,, earringearringss anandd hair-ornamenthair-ornamentss anandd brooches.. The embraceembracedd bbyy ververyy widwidee marginsmargins,, ththe carefully-placedcarefully-placed laslastt chaptechapterr describedescribess hohoww RomaRomann jewellerjewelleryy waswas photographs,, manmanyy bbyy NicNickk HalHalee anandd TinTinoo HammidHamrnid,, lealeadd manufacturemanufacturedd anandd there iiss aann afterworafterwordd iinn whicwhichh ththee ththee eyeyee naturallnaturallyy througthroughh ththee printprint.. IInn manmanyy pagepagess ththee textextt authoauthorr askaskss foforr jewellerjewelleryy anandd otheotherr ancienancientt artefactartefactss ttoo bbee iiss alsalsoo brokebrokenn uupp bbyy quotationsquotations,, printeprintedd iinn lighlightt redred,, takentaken considereconsideredd iinn contexcontextt ratheratherr thathann iinn isolatioisolationn andand foforr mormoree frofromm a varietvarietyy ooff sourcessources,, whicwhichh amplifamplifyy oorr givgivee a freshfresh carcaree ttoo bbee exerciseexercisedd bbyy ththee metametall diggerdigger.. ThThee archaeologyarchaeology imaginative dimension to the topic under discussion. imaginative dimension to the topic under discussion. ooff jewellerjewelleryy (an(andd mineraminerall collectingcollecting)) iiss nonott ththee onlonlyy areareaa iinn SSoo aass a productioproductionn ththee boobookk scorescoress ververyy highlyhighly.. AAss a whicwhichh a certaicertainn typtypee ooff tedioutediouss amateuamateurr wastewastess ththee timtimee ooff treatistreatisee oonn colourecolouredd diamonddiamondss iitt firsfirstt provideprovidess a cataloguecatalogue scholarscholarss anandd manmanyy faifaill ttoo seseee thathatt persistencpersistencee witwithh the raisonnéraisonne ttoo ththee AurorAuroraa collectiocollectionn whichwhich,, maintainemaintainedd foforr a privatprivatee possessiopossessionn ooff particulaparticularr artefactartefactss mamayy causcausee ththee lonlongg timtimee withouwithoutt additionaddition,, wawass greatlgreatlyy enhanceenhancedd inin progresprogresss ooff identificatioidentificationn ttoo bbee sloweslowedd down.down. recenrecentt yearyearss bbyy additionaadditionall specimenspecimenss provideprovidedd bbyy AlanAlan AAnn appendiappendixx givegivess detaildetailss ooff ththee BackwortBackworthh treasuretreasure BronsteinBronstein,, whowho,, witwithh ththee authorauthor,, visualizevisualized a majomajorr bookbook (Tyn(Tynee anandd Wear)Wear),, ththee SnettishamSnettisham hoardhoard,, thethe ThetfordThetford oonn colourecolouredd diamondsdiamonds.. EacEachh ooff ththee stonestoness iinn ththee collectioncollection treasurtreasuree anandd ththee HoxnHoxnee treasuretreasure.. NoteNotess relatinrelatingg ttoo the iiss fullfullyy describedescribedd anandd eaceachh ononee illustrateillustratedd ttoo shoshoww ononee ooff chapterchapterss follofolloww thithiss sectiosectionn anandd thertheree iiss aann excellentexcellent ththee wideswidestt coloucolourr rangerangess ooff diamondiamondd kepkeptt aass a singlesingle bibliography.M.O'Dbibliography. M.O'D.. collectioncollection.. ThThee formatioformationn ooff a collectiocollectionn ooff colouredcoloured diamonds is described with particular reference to the diamonds is described with particular reference to the GeGemm identificatioidentificationn madmadee easyeasy.. SecondSecond editionedition.. AurorAuroraa collectiocollectionn andand hohoww somesome ofof ththee stonesstones werewere acquired.acquired. ChapterChapterss onon rarity, buyinbuyingg andand sellingselling andand AA.. L.L. MATLINMATLlNS ANANDD AA.. C.C. BONNANOBoNNANO,, 1997.1997. GemstoneGemstone Press, 274 colourcolour perceptioperceptionn lealeadd veryvery easilyeasily ttoo ththee secondsecond majormajor Woodstock,, VTVT.. ppxxiipp xxii, 322,322, illustrateillustratedd iinn colour, 274209 themthemee ofof ththee bookbook,, ththee singularsingular importanceimportance ofof colourcolour andand hardcover.hardcover. USUS $34$34.95.95.. ISBNISBN 0 943763943763 1616 9.9. hohoww 'ttoo describedescribe itit.. DuringDuring examinationexamination ofof thesthesee topicstopics,, thethe Well-conceiveWell-conceivedd andand constructedconstructed gemgem testintestingg manuamanuall inin currentcurrent colourcolour theoriestheories areare discusseddiscussed witwithh well-drawnwell-drawn whichwhich thethe readereaderr cancan quitequite easilyeasily findfind cluesclues toto thethe nature ooff diagramsdiagrams anandd applied,applied, witwithh explanationsexplanations ofof colourcolour mostmost gemgem specimens.specimens. WritteWrittenn fromfrom thethe standpointstandpoint ooff the grading,grading, ttoo diamonds.diamonds. AllAll throughthrough ththee textextt ththee specimensspecimens retailretail jewellerjeweller,, ththee textextt beginsbegins withwith describingdescribing thethe equipmentequipment illustratedillustrated areare givengiven theirtheir provenanceprovenance wherwheree itit hashas beenbeen neededneeded byby ththee beginner,beginner, withoutwithout goinggoing tootoo deeplydeeply intointo thethe ascertainedascertained andand oneone featurfeaturee ofof thethe boobookk isis ththee notingnoting ofof principlesprinciples behinbehindd theitheirr operation.operation. InsteadInstead thethe authorsauthors importantimportant colouredcoloured diamondsdiamonds thatthat havhavee passepassedd throughthrough concentrateconcentrate uponupon eevaluatinvaluatingg thethe resultsresults obtained:obtained: a centralcentral thethe majomajorr salerooms.salerooms. I havehave longlong advocatedadvocated thethe collectioncollection colourcolour sectionsection illustratesillustrates syntheticsynthetic andand treatetreatedd gemstonesgemstones ofof saleroomsaleroom cataloguescatalogues whichwhich areare notnot usuallusuallyy indexedindexed inin witwithh excellentexcellent clcleaearr photographs.photographs. SinceSince thethe publicationpublication ooff thethe waysways gemmologistsgemmologists wouldwould want!want! thethe firstfirst editionedition inin 19891989 developmentsdevelopments inin thesethese areasareas havehave beebeenn soso extensive thatthat thethe texttext hashas beebeenn re-written.. TheThe bulkbulk TheThe glossaryglossary andand bibliographbibliographyy areare wellwell upup toto present­present- ofof thethe texttext isis writtenwritten aroundaround thethe majormajor gemgem testingtesting instru­instru­ dayday standardstandard withwith manymany citationscitations ofof significantsignificant papers.papers. mentsments andand therethere areare usefuluseful chapterschapters onon lessless commoncommon instru­instru­ InterestingInteresting sidelightssidelights onon diamond, colour,colour, buyingbuying andand mentsments andand onon thethe handlinghandling byby thethe retailretail jewellerjeweller ofof antiqueantique sellingselling aboundabound throughthrough thethe bookbook whichwhich isis a delightdelight inin andand estateestate jewellery. AppendicesAppendices includeinclude listslists ofof ususefuefull eeververyy wayway:: expensiveexpensive butbut wellwell wortworthh it.it.M.O'D M.O'D.. addressesaddresses andand a shortshort bibliography.bibliography. UsedUsed inin conjunctionconjunction withwith otherother ttextextss thisthis wouldwould makemake a goodgood additionaddition toto a TheThe JewelleryJewellery ofof RomanRoman Britain:Britain: celticCeltic andand clasclas­­ gemmologicalgemmological librarylibrary andand forfor thethe beginnerbeginner itit isis a worth­worth­ sicalsical traditionstraditions.. whilewhile firstfirst book.book.M.O'D M.O'D.. C.C. JOHNS,JOHNS, 1996.1996. UCLUCL Press,Press, London.London, pppp xvii,xvii, 246,246, iIlusillus inin black-and-whiteblack-and-white andand inin colour.colour. HardbackHardback £36.00.£36.00. Synthetic,Synthetic, imitationimitation andand treatedtreated gemstones.gemstones. ISBNISBN 1 8572885728 566566 2.2. M.M. O'DoNOGHUE,O'DONOGHUE, 19971997. ButterworthButterworth Heinemann,Heinemann, OxfordOxford,. TheThe authorauthor statesstates inin herher introductionintroduction thatthat thisthis isis thethe pppp x,x, 203.. IIlusIllus. inin black-and-whiteblack-and-white withwith 1010 pagespages ofof firstfirst generalgeneral surveysurvey devoteddevoted toto thethe jewelleryjewellery wornworn inin colourcolour plates. SoftcoverSoftcover £35.00.£35.00. ISBNISBN 0750607506 31733173 2. RomanRoman BritainBritain andand thatthat thisthis country, distantdistant fromfrom thethe FillingFilling anan importantimportant gapgap inin gemstonegemstone literature,literature, thisthis centrescentres ofof empireempire onon thethe Continent, hadhad receivedreceived lessless bookbook byby thethe well-knownwell-known author,author, lecturerlecturer andand gemmologistgemmologist considerationconsideration thanthan othersothers whenwhen ornamentornament waswas discussed.discussed. encompassesencompasses threethree relatedrelated subjectssubjects ofof synthetic,synthetic, imitationimitation TheThe bookbook takestakes 'jewellery''jewellery' asas anyany itemitem ofof personalpersonal andand treatedtreated ggememss inin aa mannermanner suitablesuitable forfor bothboth thethe adornment,adornment, whateverwhatever itit waswas mademade ofof andand equatesequates thethe studentstudent gemmologistgemmologist withwith perhapsperhaps littlelittle knowledgeknowledge ofof EnglishEnglish nounnoun jewellery toto thethe GermanGerman Schmuck.Schmuck. gemgem testingtesting techniquestechniques,, andand thethe professional.professional.

J./. Gemm., 1998,1998, 26, 4,4,273-275 273-275 Following a brief preface and introduction, the plan of As in previous issues of extraLapis the work of the the book is outlined (a glossary is mentioned here but different authors does not fall easily into separate papers: appears to have been omitted in production!) and rather, they combine their work in a long undifferentiated suggestions for further reading are listed. The book proper survey of the species. Thus we begin with topaz in then gets underway with a chapter giving an account of the antiquity, its chemical, physical and optical properties and basic ground rules and methods for the commercial growth its distribution. The main topaz-producing areas are then of synthetic gemstone crystals. This is followed by a chapter described, this task taking up most of the remainder of the on gem testing which describes the basic identification tech­ text. Considerable attention is given to topaz from niques and equipment. The next chapter, 'The major natural Schneckenstein, Saxony, and from the Russian Urals, with gemstones', describes the most important identifying crystal drawing reproductions from Goldschmidt's Atlas features of diamond, corundum, spinel, beryl, quartz, opal, der Krystallformen and from other authorities. Topaz alexandrite and topaz in order that these can be compared mining in Brazil and Pakistan as well as at other sites is with their synthetic, imitation and treated versions in the also described, with a continuous series of very fine body of the book. photographs. There is no general bibliography but this is not too serious a loss. This is altogether a beautiful Each subsequent chapter takes one of these gem species production and German printing has lost none of its skill. and describes the tell-tale features which will enable the reader to distinguish the real from the man-made or imita­ M.O'D. tion, or the untreated from the treated. One chapter deals with the organic gems, and the penultimate chapter Gemmologists' compendium. [Seventh edition.] includes other materials such as lapis lazuli, turquoise, the R. WEBSTER, revised by E.A. JOBBINS, 1998. NAG Press, synthetic garnets and cubic zirconia. The final chapter London. pp240, illus. in colour. Hardcover £16.99. covers glass, ceramics, plastics, composites and experi­ ISBN 0 7198 02911. mental materials. Many of the features described are illus­ trated by black-and-white sketches and in the book's 40 First published as a now rare and collectable small- colour plates (although the latter would have benefited format edition in 1938, this old friend has undergone from being printed larger at three-to-the-page. further revision necessitating a new edition rather than a reprint. In general appearance alone this is welcome since Perhaps the most valuable section in each of the gem the typeface is much more pleasant to read. The colour chapters is the 'Reports of interesting and unusual photographs are chiefly the work of the reviser and are examples from the literature'. Here, the author has first-class. As always there is ever more material to choose gathered together a valuable hoard of information from from and the reviser has unerringly selected a number of articles, laboratory reports, gem shows and his own gem topics for consideration outwith the glossary which observations to give the reader faced with a puzzling 209275 comprises most of the text. These topics include methods specimen the chance to find matching features among the of gemstone manufacture and treatment, colour grading more unusual gems described. scale for diamond and an update on the hazards likely to As a practical guide to ways of avoiding the pitfalls of be encountered in gem testing outside a laboratory. The misidentification, the book is a must for the jeweller, the short bibliography, too, has been updated and contains no valuer and the gemmologist.RG.R. dross (in fact it serves very well as an introduction to the subject). Topas: das prachtvolle Mineral, der lebhafte Naturally everyone will find some favourite topic Edelstein. omitted (several mentioned in the photograph captions 1997, extraLapis no. 13 (not covered by Lapis subscription). are not in the glossary) and brush aside some strays from Christian Weise Verlag, Munich, pp 95, illus. in colour. the past (not very many and not worth worrying about). Softcover DM 34.80. ISBN 3 921656 42 7 (series ISSN For general lucidity the descriptive sections would be 0945-8492). hard to beat and the junction between original author and Numbers 1 to 6 of extraLapis are already out of print reviser, apart from obvious chronological differences, is and readers who are unfamiliar with this out-of-series set imperceptible. My only criticism is that moissanite is out of thematic monographs should try hard to obtain as of sequence (but easily spotted) in the glossary and that complete a set as possible before second-hand prices there are a few unimportant typos. In my copy at least, the become unreasonably high. Since the series deals in the cover picture is quite noticeably out of focus, one large main with gem-quality minerals and precious metals specimen showing as a glaring white and upsetting the (totalling nine out of the thirteen) it is clear that this forms otherwise fine balance. The caption to the cover might be a major information resource for the study of gemstones. misread by a beginner not realizing that all specimens depicted are opals. The price is unbelievably low for Each issue that I have received seems even more today! The reviser (and the author, from some excitingly produced than its predecessors: topaz is not the unimaginable shore) should be proud.M.O'D. easiest gemstone for frequent reproduction since there is less colour variation than in some of the other species. None the less the publishers have faithfully shown the colour from yellow through to brown with amazing accuracy and as I particularly admire these colours I found the whole production the best illustrated guide to topaz that I have yet seen.

Book Reviews Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices

OBITUARY On 25 September at the Royal British Hotel, Princes Street, Edinburgh, Alan Hodgkinson gave Professor Harold Schnieden, FGA (D.1967), a talk entitled What's new in gemmology, gems, Bramhall, Stockport, Greater Manchester, died in simulants and synthetics. January 1998.

NEWS OF FELLOWS MEMBERS' MEETINGS Congratulations to Martin Donoghue, London Newlands, Glasgow, who gained top marks in the annual competition of the UK Facet Cutters7 Guild. On 8 July 1998 at the Gem Tutorial Centre, 27 This is the first time that the competition has been Greville Street, London EC IN 8TN, John Benjamin won by a gemmologist. gave a talk entitled The evolution of Georgian and 276 Victorian jewellery. 209 On 26 August at the Gem Tutorial Centre ANNUAL GENERAL MEETING Shyamala Fernandes of the Gem Testing The Annual General Meeting of the GAGTL Laboratory, Jaipur, India, gave a lecture entitled was held on 29 June 1998 at 27 Greville Street, Gemstones of India: variety, quality, availability. The London EC1N 8TN. Noel Deeks chaired the talk was illustrated by slides and a collection of meeting and welcomed those present. The Annual gemstones from India was displayed. Report and Accounts were approved and signed. Professor R.A. Howie was re-elected President for the period 1998-2000. Christopher R. Cavey Midlands Branch and Ian Thomson were re-elected to the Council of On 25 September 1998 an introductory social Management. evening was held to explore the new Branch Tony Allnutt, Robert G. Fuller and Brian meeting venue in the Earth Sciences Building of Jackson were re-elected and Sally A. Everitt, Birmingham University. A guided tour of the Amanda G. Good and Peter J. Wates elected to the Lapworth Museum was also held during the Members' Council. Messrs. Hazlems Fenton were evening. re-appointed Auditors. In response to comments from members, North West Branch further details of the figures in the accounts were provided, the desirability of improving access to On 16 September 1998 at Church House, the library was discussed, and the possibility aired Hanover Street, Liverpool 1, John Pyke Snr gave a of the laboratory extending certification of fancy talk entitled Gem collection with anecdotes. coloured diamonds. In answer to an opinion from the floor that membership of the Council of Management and the Members' Council could do Scottish Branch with some new faces, the Chairman said A field trip to Glenbuchat, Pitscurrie Quarry nominations would be welcome. and the Pass of Ballater in Aberdeenshire was held Following the Annual General Meeting, a from 25 to 27 July 1998. Reunion of Members and Bring and Buy Sale were

© Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-565 GIFTS TO THE ASSOCIATION The Association is most grateful to the following for their gifts for research and teaching purposes: The American Institute of Diamond Cutting, Deerfieid Beach, Florida, USA, for Rough diamonds: internal and external features by Nizam Peters. Mr Ismail Hussein Duale, London, for a blue beryl crystal. Mrs Shyamala Fernandes, Gem Testing Laboratory, Jaipur, India, for the Silver Jubilee book of the Jaipur Gem Testing Laboratory, a geological map of India, a picture made from various powdered gem materials, and cut gems and gem crystals from India including ruby, fluorite, feldspar, chrysoberyl, beryl, apatite, garnet and sillimanite. Mrs Sonja Glaser NVK, Galle, Sri Lanka, for 12 stones including sapphire, aquamarine, tourmaline and kornerupine. Mrs Gwyn Green, Barnt Green, Birmingham, for a collection comprising ruby, sapphire, emerald, shell cameos, pastes, garnet-topped doublets, quartz, opal, cultured pearls and pearl simulants, and many other materials, amounting to well over a thousand specimens. Professor Robert A. Howie, President of the GAGTL, for Exploring Minerals and Crystals by R.I. Gait and Rocks, Minerals and Gemstones by I.O. Evans. Mrs Brenda Hunt, London, for two pieces of opal. Mrs Ameena Kaleel, Mount Lavirda, Sri Lanka, for eight pyrite crystals Mrs Janice Kalischer, Finchley, London, for many interesting pieces including imitation coral and ivory bangles, star rubies, citrines and dress jewellery. Mr Peter H.A. Nancarrow, West Horsley, Surrey, for two pieces of turquoise from Gunheath Pit, St Austell, Cornwall. 209 Mr Daniel Piat, Paris, France, for L'émeraude, D. Giard (Editor), Assoc. Française de Gemmologie, 277 Paris, 1998. Mr Samuel R Redknap, Twickenham, Middlesex, for a microscope, a refractometer, books and journals. Miss Elisabeth Strack, Gemmologisches Institut Hamburg, Germany, for a copy of Antiker Schmuck. E.A. Thomson Gems, London, for two specimens of coated topaz.

held, at which the winners of the 1998 Sharpe, Erica J., Wells, Somerset Photographic Competition were announced and Vernon, Penny, High Wycombe, Buckinghamshire entries displayed. Zhaoyang Wu, Wuhan, Hubei, P.R. China

GEM DIAMOND EXAMINATIONS Qualified Ali, Shaukat, Karachi, Pakistan In June 1998, 97 candidates sat the Gem Anastassiou, Evangelia, Athens, Greece Diamond Examination, 71 of whom qualified, Anderson-Slight, Jamie, Horsham, West Sussex including seven with Distinction. The names of the Arnold, Jane E., London successful candidates are listed below: Ashton, David, London Au, Leslie Pak Hong, Kowloon, Hong Kong Qualified with Distinction Begley-Gray, Margaret, Little Carlton, Nottinghamshire Bell-Burrow, Briony, London Bo Zhong, Wuhan, Hubei, P.R. China Goddard, Valerie J., Alford, Surrey Britton, Andrea L., Woking, Surrey Kearton, Michael J., Eastbourne, East Sussex Brohi, Nosheen, Wanstead, London Makri, Hariklia, Thessaloniki, Greece Carter, Kevin J., Dagenham, Essex

Proceedings and Notices Chan Yuk Yee, May, Kowloon, Hong Kong Clancy, Jo, London INTERNATIONAL Cowley, Jacalyn G., Wimbledon, London GEMMOLOGICAL Damiao, Lourenco, Streatham, London CONFERENCE - '99 Dan Long, Wuhan, Hubei, P.R. China The 27th IGC will be hosted in India by De Souza, Suzanne P., Walton on Thames, Surrey the Forum of Indian Gemmologists for de Vries, Marius, London Scientific Studies, a non-profit organization Deer, Georgina, Manchester established by qualified gemmologists in Deligianni, Christina, Athens, Greece India. Edwards, Heidi L., Burntwood, Staffordshire IGC - '99 will be held in Goa from Flynn, Matthew, Amersham, Buckinghamshire 27 September to 2 October 1999 and will be Forward, Stephen, London accompanied by pre- and post-conference Franks, Ivor S., London excursions. Garrett, Frances S.J., West Worthing, West Sussex The Forum of Indian Gemmologists has Gillary, Adam J., Woodley, Reading, Berkshire set up an organizing committee to make the Hill, Emma, Maida Vale, London necessary arrangements chaired by Howard, Christine, Sevenoaks, Kent Mr K.T Ramchandran, with Dr (Mrs) Jayshree Hussain, Arshid, Birmingham, Warwickshire Panjikar as the Executive Secretary. Irwin, Edward, Limerick, Ireland Attendance at IGC is strictly by invitation Kimber, Sarah J., Weybridge, Surrey and enquiries should be directed to the Kleiser, Alwen M., Anglesey, North Wales Forum at 29 Gurukul Chambers, 187-189 Kong Jie, Beijing, P.R. China Mumbadevi Road, Bombay 400 002, India. Leung Andy Wing-Lok, Kowloon, Hong Kong Tel: +91 342 0039. Ling Yu, Wuhan, Hubei, P.R. China Liu Decai, Beijing, P.R. China Liu Feng, Beijing, P.R. China EXAMINATIONS IN 278209 Ma Si Ji, Beijing, P.R. China Michael, Marios, Limassol, Cyprus GEMMOLOGY Moore, Rowan D., Stoke, Coventry, Warwickshire In the Examinations in Gemmology held Okutu, Yula, London worldwide in June 1998, 190 candidates sat the Ouxiang Zhang, Beijing, P.R. China Preliminary Examination of whom 113 qualified. Owen, Charryn P., Rudheath, Cheshire In the Diploma Examination 234 candidates sat of Papadopoulos, Desiree, Wimbledon, London whom 96 qualified, including two with Paphitis, Constantinos, Limassol, Cyprus Distinction. The Tully Medal for the candidate Pasmooy, Pauline B., London who submits the best set of answers in the Patel, Purnima, Kintbury, Berkshire Diploma Examinations in 1998 which, in the opinion of the Examiners, are of sufficiently high Perks, Helen E., Kinver, Staffordshire standard, was awarded to Mr Laurent Kellerson of Pinter, Max, London London. Mr Kellerson was also awarded the Raphael, Menachem, Alwoodley, Leeds, West Anderson Bank Prize for the best non-trade candi­ Yorkshire date of the year in the Diploma Examination. Reilly, Clare, Sutton Coldfield Reineke, Antony M., Chelsea, London The Diploma Prize for the best candidate of the Rennes, Michael, London year who derives her main income from activities Shi Yan, Beijing, P.R. China essentially connected with the jewellery trade was Shun Yam Yau, Kowloon, Hong Kong awarded to Miss Tina Notaro of Madison, Smith, Colin, Teddington Wisconsin, USA. Tete, Nair C, Waltham Cross, Hertfordshire The Anderson Medal for the best candidate of Uhlin, Christophe, Leytonstone, London the year in the Preliminary Examination was Vassiliou, Marianna, London awarded to Miss Long Chu of Guilin, P.R. China. Wealthall-Morrison, Maxine, Cold Ash, Berkshire The Preliminary Trade Prize for the best White, Joannne C, Sheffield, South Yorkshire candidate of the year who derives her main Willis, Keith T.J., Romford, Essex income from activities essentially connected with Wong King Suen, Kowloon, Hong Kong the jewellery trade was awarded to Miss Linda Yoshitake, Yumi, Golders Green, London Rythen of Stockholm, Sweden.

/. Gemm., 1998, 26, 4, 276-284 FORTHCOMING EVENTS 1NovemberAnnual Conference. Gems in Jewellery. To be held at the Barbican Centre, London. Current issues concerning gems and jewellery presented by a distin­ guished gathering of experts,

2NovemberTours of jewellery and gemstone galleries at two London museums.

4NovemberLondon. F.EH, Moissan, polytypes and synthetic moissanite. Kurt Nassau.

12NovemberScottish Branch. Moissanite, a new diamond simulant. Kurt Nassau.

18 NovemberNorth West Branch. Annual General Meeting.

27 NovemberMidlands Branch. Gemmological journeys in Brazil. £. Alan Jobbins.

5DecemberMidlands Branch 46th Annual Dinner.

1999

13JanuaryLondon. Insects in amber. Andrew Ross.

29 JanuaryMidlands Branch. Bring and Buy followed by Quiz.

26 FebruaryMidlands Branch. Cameo and gemstones carvings. David Callaghan

11 MarchLondon. Some current problems in diamond research. Dr H. Judith Milledge.

26 MarchMidlands Branch. Jewels in the hand. James Gosling

For further information on the above events contact: 209279 London:Mary Burland on 0171 404 3334 Midlands Branch: Gwyn Green on 0121445 5359 North West Branch: Deanna Brady on 0151 648 4266 Scottish Branch: Catriona Mclnnes on 0131667 2199

GAGTL WEB SITE For up-to-the-minute information on GAGTL events and workshops visit our web site on www.gagtLac.uk/gagtl

The names of the successful candidates are as Bin Gao, Wuhan, Hubei, RR. China follows: Boels, Vigdis, leper, Belgium Burgoyne, Sheila, Totteridge, London Diploma Castoro, Loretta C, New York, USA Cho Ka Wah, Hong Kong Qualified with Distinction Combee, Mireille M., Capelle aan den Yssel, The Kellerson, Laurent P., London Netherlands Notaro, Tina M., Madison, Wisconsin, USA Cooksey, Brian, Bures St. Mary, Suffolk Dalsplass, Line M., Oslo, Norway Qualified French, Thomas, Woking, Surrey Amor, Miranda, Taunton, Somerset Fujii, Noriyuki, Higashi, Osaka, Japan Astor, Flora, London Fujiwara, Motoko, London Avery, Hilary E., Bangor, Co. Down, N. Ireland Gudmundson, Inger, Lit, Lannavaara, Sweden

Proceedings and Notices Haitsma, Maaike C, Schoonhoven, The Netherlands Taylor, Christopher, Selsdon, Surrey Han Xiao, Guilin, Guangxi, P.R. China Thomas, Caan, Chesham, Buckinghamshire Harding, Rachel A., Twickenham, Middlesex Usami, Yumi, Suita City, Osaka, Japan Haris, Mohamed Thowfeek Mohamed, Maggona, Wang Shu-Ying, Taipei, Taiwan, R.O. China Sri Lanka Waring, Paul, Highbury, London Hodgson, Jane E., Watford, Herfordshire Watson, Mendis A., Toronto, Ontario, Canada Hong, Angela, London Weisheng Wen, Wuhan, Hubei, P.R. China Hsiao Chin-Kang, Taipei, Taiwan, R.O. China Wu Tsai-Yi, Taipei, Taiwan, R.O. China Ikebe Emi, London Xianshu Li, Wuhan, Hubei, P.R. China Ikeda, Yumi, Osaka City, Osaka, Japan Xu Lizhen, Guangzhou, P.R. China Inoue, Kazuko, Tokyo, Japan Yahampath, Hirosha, Maharagama, Colombo, Sri Jacky Lee Chun Man, Hong Kong Lanka Jain, Reena, Jaipur, India Yamashita, Yuko, Osaka, Japan Jing Zhang, Wuhan, Hubei, RR. China Yang Sibo, Guilin, Guangxi, PR. China Jones, Jesse, Auckland, New Zealand Ye Li, Wuhan, Hubei, P.R. China Jung-In Yang, Taegu, R.O. Korea Yeung, Michelle, Thornhill, Ontario, Canada Kim Mi Young, Taegu, R.O. Korea Yin Xiong, Wuhan, Hubei, P.R. China Konstandopoulou, Garoufallia, Athens, Greece Ying Zhang, Wuhan, Hubei, P.R. China Kuroda, Chikako, Kawanishi City, Hyogo Pref, Japan Ying Liana Ching, North York, Ontario, Canada Lam Lai Chun, Kowloon, Hong Kong Yixiang Zhang, Wuhan, Hubei, P.R. China Lanz, Ernst, Veytaux, Switzerland Yizhi Huang, Wuhan, Hubei, P.R. China Lee Yin Wa, Kowloon, Hong Kong Yoneda, Chie, Nishinomiya City, Hyogo, Japan Lempinen, Marita, Lahti, Finland Young, Geoffrey W, Surbiton, Surrey Liying Fan, Shanghai, P.R. China Zhimei Wei, Shanghai, P.R. China Long Chu, Guilin, Guangxi, P.R. China Zou Hon Wah, Hong Kong Lule, Cigdem, Ankara, Turkey Maddison, Steven, Benfleet, Essex Makri, Hariklia, Thessaloniki, Greece Preliminary 280209 Marshall, Andrew P., Gravesend, Kent Adcock, Graham D., Lutterworth, Leicester Miwa, Yosuke, Tokyo, Japan Asanuma, Yukiko, Kyoto, Japan Miyamoto, Takuya, Himeji City, Hyogo Pref, Japan Atarashi, Yoshie, Osaka, Japan Miyamura, Kayoko, Otsu city, Shiga Pref, Japan Bai Chen Guang, Guilin, P.R. China Morgan, Jacqueline, London Bartels, Daphne K., Schoonhoven, The Netherlands Murakoshi, Mitsuko, Nagareyama City, Chiba Birrer, Julia M., Ruttenen, Switzerland Pref, Japan Borg, David, Paola, Malta Muratsu, Hirotoshi, Neyagawa, Osaka, Japan Boyle, Joyce, Clonakilty, R. Ireland Nakazawa, Haruyo, London Chang Kang Jung, Taipei, Taiwan, R.O. China Ning Zhang, Wuhan, Hubei, P.R. China Cheng Qing Ye, Singapore Nishimura, Yoko, Nabari City, Mie Pref, Japan Cheng Chin-Sheng, Taipei, Taiwan, R.O. China Nunn-Weinberg, Danielle, Toronto, Ontario, Canada Cheung Sze Wai, Lantau Island, Hong Kong O'Byrne, Rose-Marie, Bicester, Oxon Cheung Kwok Man, Kowloon, Hong Kong Okamoto, Chizuko, Kochi, Japan Christoylakis, Theodore, Athens, Greece Ono, Shiho, Kaidori Tama City, Tokyo, Japan Chun Choi Sun Young, Yangon, Myanmar Patel, Nita, Newbury, Berkshire Clouder, Carol J., Southampton Peng Gao, Guangzhou, P.R. China de Landmeter, Edward, Schoonhoven, The Plitsi, Catherine, Larissa, Greece Netherlands Qiong Wei, Wuhan, Hubei, P.R. China Dennis, Damon, S., Stamford, Lincoln Ramirez-Achinelli, Soledad, London Dines, Rachel S., London Richardson, Julia H., London Ding He, Guilin, Guangxi, P.R. China Said, Mohammad Ali, Göteborg, Sweden Dittrich, Helene, Utrecht, The Netherlands Segelken, Christine, Vancouver, Canada Donnelly, Lee-ona, F., Ayr, Scotland Shah, Varsheet, Kingston, Surrey Dower, Daniel, G., London Sheng Chun-Wei, Taipei, Taiwan, R.O. China Ellis, Nigel C, Tasmania, Australia Shyng Jin Chyr, Taipei, Taiwan, R.O. China Englezos, Antonios, Birmingham, Warwickshire Smits, Cyntha, Alphen a/d Rijn, The Netherlands Farrell, Terry, Cambridge Stern, Sara, Arlington, Virginia, USA Fingland, Samantha, Condorrat, Cumbernauld, Stratton, Claire A., London Scotland

/. Gemm., 1998,26,4,276-284 GEGEMM TUTORIATUTORIALL CENTRCENTREE 2277 Grevill Grevillee Street Street,, Londo Londonn EC1 ECINN 8S8SUU

EVERYDAEVERYDAYY LIFLIFEE -- TREATMENTTREATMENTSS ANANDD SYNTHETICSYNTHETICSS 2288 OctobeOctoberr ThiThiss one-da one-dayy cours coursee wil willl loo lookk a att th thee synthetic synthetic,, imitatio imitationn an andd treate treatedd materialmaterialss encountereencounteredd i nin th thee jeweller jewelleryy trad tradee today today.. Th Thee cours coursee wil willl concentrat concentratee o onn emerald emerald,, rubyruby,, sapphirsapphiree an andd diamond diamond,, emphasizin emphasizingg observatio observationn techniques techniques.. PricePrice £80 + VATVAT (£94.00) (£94.00) - -Includes Includes a sandwich a sa?idwich lunch lunch

OPALOPALSS -- GLORIOUGLORIOUSS TECHNICOLOTECHNICOLORR 33 NovembeNovemberr AAnn opportunit opportunityy t oto se seee a a privat privatee collectio collectionn o off som somee o off th thee fines finestt gem-qualitgem-qualityy opalopalss iinn ththee world world!! JoiJoinn Davi Davidd Callagha Callaghann fo forr a ann in-dept in-depthh loo lookk a att opals opals.. DavidDavid,, wh whoo wa wass witwithh HancockHancockss && Co. Co. Ltd Ltd.. o off Londo Londonn fro fromm 195 19555 t oto 19971997,, hahass lon longg bee beenn aann aviavidd fafann ooff thesthesee beautifubeautifull stonesstones.. Thi Thiss one-da one-dayy worksho workshopp will will loo lookk a att th thee variou variouss aspect aspectss ooff opal opalss includinincludingg nomenclaturenomenclature,, synthetics synthetics,, imitation imitationss an andd treatmentstreatments.. PricePrice £104 ++ VATVAT (£122.20) (£12220) - -Includes Includes a sandwicha sandwich lunch lunch 209281281 STUDENSTUDENTT WORKSHOPWORKSHOPSS Preliminary Workshop 21 October Preliminary Workshop 21 October Preliminary Theory Review 9 November Preliminary Theory Review 9 November Three-day Preliminary Workshop 9 to 11 November Three-day Preliminary Workshop 9 to 11 November Diploma Theory Review 23 November Diploma Theory Review 23 November Four-day Diploma Workshop 23 to 26 November Four-day Diploma Workshop 23 to 26 November Weekend Diamond Grading Revision 12 and 13 December Weekend Diamond Grading Revision 12 and 13 December Two-day Diploma Practical Workshop 9 and 10 January 1999 Two-day Diploma Practical Workshop 9 and 10 January 1999

For further details contact the GAGTL Education Department For further details contact the GAGTL Education Department Tel: +44 (0)171 4043334 Fax: +44 (0)1714048843 Tel: +44 (0)171404 3334Fax: +44 (0)171 404 8843

Grauwiller,Grauwiller, Robert,Robert, Freiburg,Freiburg, SwitzerlandSwitzerland Iqbal,Iqbal, Zaigham,Zaigham, SingaporeSingapore Grostate,Grostate, StephenStephen E.,E., LondonLondon JiJi Yan,Yan, Shanghai,Shanghai, P.RRR. ChinaChina Guzman,Guzman, CarolinaCarolina c.,C, LondonLondon Jinsenji,Jinsenji, Osamu,Osamu, TodaToda City,City, JapanJapan Haden,Haden, ClaireClaire L.,L., Birmingham,Birmingham, WarwickshireWarwickshire Keane,Keane, Barbara,Barbara, Kilkenny,Kilkenny, IrelandIreland Ho,Ho, PaulaPaula S.Y.,S.Y., LondonLondon Keating,Keating, MichelleMichelle E.,E., Kilkenny,Kilkenny, IrelandIreland Hooley,Hooley, Julie,Julie, Birmingham,Birmingham, WarwickshireWarwickshire Houser,Houser, ElizabethElizabeth,, Burbank,Burbank, California,California, USUSAA Kemmesies,Kemmesies, Heidi,Heidi, Toronto,Toronto, Ontario,Ontario, CanadaCanada HsiaoHsiao ChinChin Kang,Kang, Taipei,Taipei, Taiwan,Taiwan, RO.R.O. ChinaChina Kinnaird,Kinnaird, JudithJudith A.,A., Fife,Fife, ScotlandScotland HuHu YiYi Qing,Qing, Guangzhou,Guangzhou, P.RRR. ChinaChina KwonKwon SungSung HaeHae Yoon,Yoon, Yangon,Yangon, MyanmarMyanmar Hugo,Hugo, Philippe,Philippe, KortrukKortruk,, BelgiumBelgium KwongKwong WanWan Sze,Sze, Fanling,Fanling, HongHong KongKong

Proceedings andand NoticesNotices Lai Kar Cheung, Apleichau, Hong Kong Van der Have, Ciska A., Amsterdam, The Lam King Nam, Hong Kong Netherlands Lam Ho Keung, Kwai Chung, Hong Kong Van der Made, Barbara, Oegstgeest, The Lawrence, Rebecca C, London Netherlands Lee Seung-Jun, Taegu, Korea Walker, Zoe, Walsall, West Midlands Lei Wei Hong, Singapore Withington, Philip K., Shifnal, Shropshire Li Zhi Jun, Guilin, Guangxi, RR. China Wu Oi Lin, Shing, Hong Kong Li Ru Tian, Guilin, Guangxi, RR. China Xayaboun Singkham, Felsberg, Switzerland Lin Ling, Guilin, Guangxi, P.R. China Yan, Lesley, Toronto, Ontario, Canada Liu Meng Na, Guilin, Guangxi, RR. China Yeung Wan Ki, Twuen Wan, New Territories, Hong Liu Kaiting, Guangzhou, RR. China Kong Lopez Perez, Jose M., Valencia, Spain Ying Liana Ching, Toronto, Ontario, Canada Lu Ning, Shanghai, P.R. China Yu Shi-Wei, Shanghai, P.R. China Michael, Marios, Limassol, Cyprus Yun Dong, Guilin, Guangxi, P.R. China Miles, Damian J., Newton Abbott, Devon Zin Win Mon, Yangon, Myanmar Mossuto Mori, Maria E., Yangon, Myanmar Negard, Janne, Skein, Norway Ocloo, Charles S., London SUBSCRIPTIONS 1999 Odber, Marianne R., Surrey, British Columbia, The following are the membership subscription Canada rates for 1999. Existing Fellows, Diamond Okamoto, Mayumi, Osaka, Japan Members and Ordinary Members will be entitled Osborne-Shaw, Lisa M., London to a £5.00 discount for subscriptions paid before 31 Oya, Kenichi, Niigata City, Japan January 1999. Panidis, Lydia, Elefsina, Greece Papanastasiou, Evangelia, Volos, Greece Fellows, Diamond Laboratory Park Jong Hun, Daejon, Korea Members and Members Pe Thu Aung, Yangon, Myanmar Ordinary Members Petropoulos, Andreas, Athens, Greece UK £57.00 £250.00 plus 282209 Plant, Monika, Knutsford, Chester VAT Poon Wai Kong, Singapore Pratt, Jonathan J., Guildford, Surrey Europe £64.00 £250.00 Price, Sharron A., Regis, West Midlands Overseas £72.00 £250.00 Qiu Jian, Guilin, Guangxi, P.R. China Rochford, Bronwen, County Dublin, Ireland Rockman, Gary, Bromley, Kent Rythen, Linda, Stockholm, Sweden MEETINGS OF THE COUNCIL OF Sakai Junko, Otsu City, Japan MANAGEMENT San Zar Aung, Yangon, Myanmar At a meeting of the Council of Management Schepers, Reinhold M, Limbricht, The Netherlands held at 27 Greville Street, London ECIN 8TN on Sheng Chung-Wei, Taipei,, Taiwan, R.O. China 24 June 1998 the business transacted included the Sheppard, Gary, Wellington, New Zealand election of the following: Shyng Jin Chyr, Taipei, Taiwan, R.O. China Simpson, Peter R., London Slightam, Rachel L., Guildford, Surrey Fellowship (FGA) Son Hyun-Mok, Taegu, Rep. of Korea Arbeid, Martin Jolis, Dulwich, London. 1967 Sperry, Lynn M., London Chan, Sau King, Hong Kong. 1998 Stewart, Michelle, Stourport-on-Severn, Dirlam, Dona Mary, Carlsbad, California, USA. 1982 Worcestershire Ho, Chuan-Hsiang Taipei, Taiwan, R.O. China. 1998 Tanaka, Rika, Yangon, Myanmar Htun, Han, Yankin, Yangon, Myanmar. 1998 Tezapsidou, Eleni, Birmingham, Warwickshire Thiha Zaw, Yangon, Myanmar Thomas, Allyson R., Birmingham, Warwickshire Ordinary Membership Torndahl, Rebecca, Stockholm, Sweden Garbis, Nikolaos, Argostoli, Kefalonia, Greece Townsend, Rachel E., Tamworth, Stafford Hicter, Marie-Irene, Grenoble, France Tsutsumi, Masao, Hiroshima, Japan Knifeld, Stephanie Ann, Bournemouth, Dorset Ulbricht, Mary E., Washington, USA Leaver, Shirley, Edgeley, Stockport, Cheshire V. Dam, Anita, Kwintsheul, The Netherlands Lima Da Costa, Marcondes, Belem, PA, Brazil

/. Gemm., 1998,26,4,276-284 Oparaeche, Charles, Brixton, London Diamond Membership and Porter, Alan Redvers, Capel, Dorking, Surrey Fellowship (FGA/DGA) Rajkumar, Rajendran, Cardiff, Glamorgan Said, Mohammad Ali, Gothenburg, Sweden Herold, Richard A.J., Bordon, Hampshire. 1985/86 Speer, Teresa Ann, Mountsorrel, Leicestershire At a meeting of the Council of Management Fellowship (FGA) held at 27 Greville Street, London EC1N 8TN on 29 Avery, Hilary E., Bangor, Co. Down, N. Ireland. 1998 July 1998 the business transacted included the Beevers, Jacintha Mary, Henley-on-Thames, election of the following: Oxfordshire. 1981 Boels, Vigdis L.N., Ypres, Belgium. 1998 Diamond Membership (DGA) Chung, Stephen, Leeds, Yorkshire. 1986 Combee, Mireille M., Capelle a/d Yssel, The Karim, Zapherali, Leicester. 1998 Netherlands. 1998 Fujiwara, Motoko, Nagoya City, Aichi, Japan. 1998 Fellowship (FGA) Haitsma, Maaike C, Gouda, The Netherlands. 1998 Haris, Mohamed Thowfeek Mohamed, Colombo, Jankowiak, Anna H., Toronto, Ontario Canada. 1997 Sri Lanka. 1998 Mutton, Valerie Jean, Langley, Berkshire. 1998 Hong, Angela S.L., London. 1998 van Keulen, Simone J. C, Amsterdam, The Jones, Jesse, Auckland, New Zealand. 1998 Netherlands. 1992 Lanz, Ernst, Veytaux, Switzerland. 1998 Lempinen, Marita, Lahti, Finland. 1998 Ordinary Membership Notaro, Tina M., Madison, Wisconsin, USA. 1998 Taylor, Christopher, Selsdon, Surrey. 1998 Cunningham, Janice, Worcester Park, Surrey Waring, Paul M., Highbury, London. 1998 Gandy, Peter John, Ashburton, Devon Wu, Tsai-Yi, Taipei, Taiwan, R.O. China. 1998 Houser, Elizabeth P.Q., Burbank, Calif., USA Koudou, Dally, East Ham, London McKittrick, Christopher D., Belfast, N. Ireland Ordinary Membership 209283 Rythen, L.A. Carolina, Stockholm, Sweden Ancemot, Alexandre, London Smith, Katrina, Dartmouth, Devon Andries, Stephanie U.S., London Whitehead, James Devereux, Eastcote, Ruislip, Arrowsmith, Jodie, Oxhey, Hertfordshire Middlesex Bailey, Leigh-Ann, Hornchurch, Essex Bashore, Kerri A., Hayes End, Middlesex Laboratory Membership Dennis, Roger A., Elstree, Hertfordshire Dhillon, Amritpal S., Kenton, Harrow, Middlesex R.D. Finnie Ltd, Aberdeen, Scotland Domercq, Saudrine, London Hallam, Antique and Diamond Jewellery, Duncan, Neil A., Twickenham, Middlesex Nottingham Dunning, Roy W. J.,Watford, Hertfordshire At a meeting of the Council of Management Eggebratt, Pauline, Sundbyberg, Sweden held at 27 Greville Street, London EC1N 8TN on 23 Frei, Eliav, London September 1998 M.J. O'Donoghue FGA was Frewen, Charles G.J., S„o Paulo, Brazil appointed to the Council. The business transacted Galdeano, Nerea, Golders Green, London also included the election of the following: German, Ruth I., Teddington, Middlesex Goudge, Rebecca, Kilburn, London Greenwood, Alan P., Colchester, Essex Diamond Membership (DGA) Haider, Hamayou, Norbury, London Ali, Shaukat, Karachi, Pakistan. 1998 Hayes, Toni, St Louis, Missouri, USA Au, Pak Hong, Kowloon, Hong Kong. 1998 Jeffrey, Robert Thomson, Elgin, Moray, Scotland Carter, Kevin J., Dagenham, Essex. 1998 Kamil, Mohammed, Harrow Weald, Middlesex Damiao, Lourenco G., Streatham, London. 1998 Katada, Mitsura, Oxhey, Hertfordshire Hussain, Arshid, Birmingham, Warwickshire. 1998 Khan, Mahbubar R., Dhaka, Bangladesh Irwin, Edward, Limerick, Ireland. 1998 Kishan, Niraj, New Delhi, India Leung, Wing Lok, Kowloon, Hong Kong. 1998 Kukadia, Dave, Feltham, Middlesex Pasmooy, Pauline B., London. 1998 Kukadia,Dharmesh, Feltham, Middlesex Reineke, Antony M., Chelsea, London. 1998 Kulukundis, John, London Willis, Keith, Romford, Essex. 1998 Lee, Martin, South Croydon, Surrey

Proceedings and Notices Maslik, Magdalena, Fulham, London Transfer from Ordinary Membership Matthews, Suzanne, San Francisco, Calif., USA to FGA Murase, Yuka, Croydon, Surrey Nunn, Eva K., London Astor, Flora, London Pace, Michael, Elk Grove, Calif., USA Burgoyne, Sheila, Totteridge, London Panos, Masis R., Leyton, London Castoro, Loretta C, New York, NY, USA Perez-Dorao, Karlos, Golders Green, London Cooksey, Brian D., Bures St Mary, Suffolk Perry, Michael, Dublin, Ireland Fujii, Noriyuki, Higashi-Osaka City, Osaka, Japan Pert, John, Windsor, Berkshire Hodgson, Jane E., Watford, Hertfordshire Petkov, Nikolay, Bayswater, London Ikeda, Yumi, Osaka City, Osaka, Japan Prince, Ronald Fisher, Richmond, Surrey Konstandopoulou, Garoufallia, Athens, Greece Rose, Christine, Muscat, Sultanate of Oman Kuroda, Chikako, Kawanishi City, Japan Schonberg, Eva A., London Marshall, Andrew P., Gravesend, Kent Sinclair, Gary, London Miwa, Yosuke, Tokyo, Japan Vallejo-Nagera, Maria, London Miyamoto, Takuya, Hyogo Pref., Japan Waterfall, Mary C, Ely, Cambridgeshire Miyamura, Kayoko, Otsu City, Shiga Pref., Japan Wheeler, Nick, Sudbury, Suffolk Murakoshi, Mitsuko, Nagareyama City, Chiba Pref., Japan Muratsu, Hirotoshi, Neyagawa City, Osaka, Japan Laboratory Membership Nakazawa, Haruyo, London Richard Herold Jewellers Ltd, Bordon, Hants. Nishimura, Yoko, Nabari City, Mie Pref., Japan O'Byrne, Rose-Marie, Bicester, Oxfordshire Patel, Nita, Newbury, Berkshire Transfers Ramirez-Achinelli, Soledad, Skogas, Sweden Transfer from DGA to FGA DGA Said, Mohammad Ali, Göteborg, Sweden Shah, Varsheet, Kingston, Surrey Lule, Cigdem, Ankara, Turkey Stern, Sara, Arlington, Virginia, U.S.A. 284 Thomas, Caan M., Chesham, Buckinghamshire 209 Transfer from Ordinary Membership Usami, Yumi, Suita City, Osaka, Japan to FGA DGA Yamashita, Yuko, Sakai City, Osaka, Japan Yoneda, Chie, Nishinomiya City, Hyogo, Japan Makri, Hariklia, Thessaloniki, Greece Young, Geoffrey W, Surbiton, Surrey

Transfer from FGA to FGA DGA Transfer from Ordinary Membership Anastassiou, Evangelia, Athens, Greece to DGA Britton, Andrea L., Woking, Surrey Cowley, Jacalyn G., Wimbledon, London Anderson-Slight, Jamie G., Horsham, West Sussex Deligianni, Christina, Athens, Greece Arnold, Jane E., London Edwards, Heidi L., Burntwood, Staffordshire Ashton, David, London Forward, Stephen, London Begley-Gray, M. M., Newark, Nottinghamshire Franks, Ivor S., London Bell-Burrow, Briony, London Goddard, Valerie J., Alfold, Surrey de Vries, Marius L., London Hill, Emma, Maida Vale, London Flynn, Matthew, Amersham, Buckinghamshire Kearton, Michael J., Eastbourne, East Sussex Garrett, Fran S.J., West Worthing, West Sussex Kimber, Sarah J., Weybridge, Surrey Gillary, Adam J., Reading, Berkshire Kleiser, Alwen M., Llanfachaeth, Anglesey, North Michael, Marios, Limassol, Cyprus Wales Okutu, Yula, London Moore, Rowan D., Stoke, Coventry, Warwickshire Paphitis, Constantinos, Limassol, Cyprus Raphael, Menachem, Alwoodley, Leeds, West Patel, Purnima, Kintbury, Berkshire Yorkshire Perks, Helen E., Kinver, Staffordshire Sharpe, Erica J., Wells, Somerset Pinter, Max, London Vernon, Penny A., High Wycombe, Rennes, Michael D., New Cross, London Buckinghamshire Tete, Nair C, Antwerp, Belgium White, Joanne C, Sheffield, South Yorkshire Vassiliou, Marianna, Nicosia, Cyprus Wong King Suen, Kowloon, Hong Kong Wealthall-Morrison, Maxine, Cold Ash, Yoshitake, Yumi, Golders Green, London Berkshire

/. Gemm., 1998,26,4,276-284 ADVERTISING Idar Oberstein in the Journal of Gemmology 1999 The Editors of the Journal invite advertisements from gemstone and The 5th GAGTL tour to mineral dealers, publishers, and the gem centre of others with interests in the Germany gemmological, mineralogical, lapidary and jewellery fields. Sunday I11 I April to Saturday 19 April 1999 Rates per insertion, excluding VAT, are as follows: Visits to museums, mines, workshops, Whole page Half page Quarter page showrooms and much more! £180 £100 £60 For further information and a booking Enquiries to Mary Burland, form contact Sarah Kimber at the GAGTL, 27 Greville Street, London EClN 8TN GAGTL on 01714053351 Tel: 0171 4043334 Fax: 0171 4048843 e-mail [email protected]

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Proceedings and Notices 209286174286

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209288 288 "Museums,Museums, EducationaEducationall EstablishmentsEstablishments,, CollectorCollectorss & StudentStudentss I have what is probably the largest range I have what is probably the largest range of genuinely rare stones in the UK, from of genuinely rare stones in the UK, from Analcime to Wulfenite. Also rare and Analcimmoderne synthetics,to Wulfenite and. Als inexpensiveo rare and crystamoderlsn andsynthetics stones, foran dstudents. inexpensiv Newe crystals and stones for students. New MAGGIE CAMPBELL PEDERSEN computerised lists available with even MAGGIE CAMPBELL PEDERSEN computerised lists available with even ABIPP, FGA more detail. Please send £2 in 1st class ABIPP, FGA morestamps detail .refundable Please sen ond £ first2 in order1st clas s stamps refundabl(oversease free).on firs t order (overseas free). JEWELLERY & GEMSTONE Two special offers for students: JEWELLERPHOTOGRAPHYY & GEMSTON E TwNewo specia Teach/Buyl offer services for students and free: PHOTOGRAPHY New Teach/Bustones ony servican order.e an d free stones on an order. AJ. French, FGA 82 BrookleyAJ. French Road, ,Brockenhurst, FGA Tel: 0181-994 8341 82 BrookleHantsy Road S042, Brockenhurst 7RA , Fax:Tel: 0181-990181 -7234 83442661 Telephone:Hants S04 015906232142 7RA Fax:0181-723 4266 LTelephone: 01590 623214 Guide to the preparation of typescripts for publication in The Journal of Gemmology

The Editor is glad to consider original articles Illustrations Either transparencies or shedding new light on subjects of gemmological photographs of good quality can be submitted interest for publication in The fOl/mal. Articles for both coloured and black-and-white arearc not normally accepted which have already illustrations. It is recommended that authors been published elsewhere in English, and an retain copies of all illustrations because of the article is accepted only on the understanding risk of loss or damage either during the printing that (1) full information as to any previous process or in transit. publication (whether in English or another Diagrams must be of a professional quality language) has been given, (2) it is not under and prepared in dense black ink on a good consideration for publication elsewhere and (3) quality surface. Original illustrations will not be it will not be published elsewhere without the returned unless specifically requested. consent of the Editor. All illustrations (maps, diagrams and Typescripts Two copies of all papers should be pictures) are numbered consecutively with submitted on A4 paper (or USA equivalent) to Arabic numerals and labelled Figure 1, Figure the Editor. Typescripts should be double spaced 2, etc. All illustrations are referred to as with rnargins of at least 25 mm. They should be 'Figures'. set out in the manner of recent issues of The Tables Must be typed double spaced, using Journal and in conformity with the information few horizontal rules and no vertical rules. They set out below. Papers may be of any length, but are numbered consecutively with Roman long papers of more than 10 000 words (unless numerals (Table IV, etc.). Titles should be capable of division into parts or of exceptional concise, but as independently informative as importance) arearc unlikely to be acceptable, possible. The approximate position of the Table whereas a short paper of 400-500 words may in the text should be marked in the margin of the achieve early publication. typescript. The abstract, references, notes, captions and Notes and References Authors may choose tables should be typed double spaced on one of two systems: separate sheets. (1) The Harvard system in which authors' On matters of style and rendering, please names (no initials) and dates (and specific consult Tile Oxford dictionary for writers alldand pages, only in the case of quotations) are given editors (Oxford University Press, 1981"). in the main body of the text, e.g. (Giibelin and Koivula, 1986, 29). References are listed Title page The title should be as brief as is alphabetically at the end of the paper under the consistent with clear indication of the content of heading References. the paper. It should be followed by the names (2) The system in which superscript numbers (with initials) of the authors and by their are inserted in the text (e.g .... to which Giibelin addresses. refers.') and referred to in numerical order at the Abstract A short abstract of 50-100 words is end of the paper under the heading Notes. required. Informational notes must be restricted to the m1l11mUm; usually the material can be Key Words Up to six key words indicating the incorporated in the text. If absolutely necessary subject matter of the article should be supplied. both systems may be used. Headings In all headings only the first letter References in both systems should be set out and proper names are capitalized. as follows, with double spacil1gspacing for all lines. A This is a first level heading Papers Hurwit, K., 1991. Gem Trade Lab notes. GemsGenis & Gemology,Gel1lology, 27, 2, 110-11 First level headings are in bold and are flush left on a separate line. The first text line Books Hughes, R.W., 1990. Corundul1l.Corundum. following is flush left. Butterworth-Heinemann, London. p. 162 Abbreviations for titles of periodicals are B This is a secondsecol1d level headingheadil1g those sanctioned by the World List of scientificsciel1tific Second level headings are in italics and are periodicals 4th edn. The place of publication flush left on a separate line. The first text line should always be given when books are following is flush left. referred to. Volume 26 No. 4 October 1998 Contents

Blue euclase from Zimbabwe - a review 209 S. Stocklmayer

Further aspects of the history of rose-cut diamonds 219 H. Tillander

Kyanite in diamond identified by Raman analysis 222 J.I. Koivula and S. Elen

Tourmaline: morphological and compositional variations 226 during the growth history of uvite single crystals Y. Takahashi and I. Sunagawa

Maxixe-type colour centre in natural colourless beryl 238 from Orissa, India: an ESR and OA investigation G. Mathew, R.V. Karanth, T.K. Gundu Rao and R.S. Deshpande

The chemical signature of emeralds from the Campos 252 Verdes-Santa Terezinha Mining Distrinct, Goias, Brazil GM. Pulz, LJ.H. D'el-Rey Silva, L.S. Barros Neto, TM.M. Brum, P.L. Juchem, C.A. Santos, V.R Pereira and J J. Silva

An interdisciplinary approach to identifying solid 262 inclusions in corundum: thorite in a 'Sri Lanka7 sapphire S. Carbonin, G. Sbrignadello and D. Ajb

Abstracts 266

Cover Picture Book Reviews 273 Tourmaline crystal showing prominent basal Proceedings of the Gemmological Association and Gem 276 and pyramidal faces Testing Laboratory of Great Britain and Notices resting on sketches of the growth step patterns of a Copyright © 1998 pyramidal face. (see the paper on The Gemmological Association and tourmaline by Takahashi Gem Testing Laboratory of Great Britain and Sunagawa, Registered Office: Palladium House, 1-4 Argyll Street, London W1V 2LD pp 226-37)

ISSN: 1355-4565 Printed by Quadrant Offset Limited, Hertford, England