Volume 22 No. 5. January 1991 The Journal of Gemmology

THE GEMMOLOGICAL ASSOCIATION AND GEM TESTING LABORATORY OF GREAT BRITAIN OFFICERS AND COUNCIL

Past Presidents: Sir Henry Miers, Ma, D.Sc, FRS Sir William Bragg, OM, KBE, FRS Dr. G.F Herbert Smith, CBE, MA, D.Sc. Sir Frank Claringbull, Ph.D., F.Inst.E, FGS Vice-President: R. K. Mitchell, FGA

Council of Management D.J. Callaghan, FGA N.WDeeks,FGA N.B. Israel, FGA E.A. Jobbins, B.Sc, C.Eng., FIMM, FGA I. Thomson, FGA V.E Watson, FGA K. Scarratt, FGA : Chief Executive R.R. Harding, B.Sc, D.Phil., FGA : Director of Gemmology

Members' Council A.J.Allnutt,M.Sc, D. Inkersole, FGA PG. Read, C.Eng., Ph.D.,FGA B. Jackson, FGA MIEE, MIERE, FGA C. R. Cavey, FGA G.H. Jones, B.Sc, Ph.D., FGA I. Roberts, FGA P J. E.Daly, B.Sc, FGA H. Levy, M.Sc,BA, FGA E.A. Thomson, T. Davidson, FGA J. Kessler Hon. FGA R. Fuller, FGA G. Monnickendam R. Velden J.A.W Hodgkinson, L. Music D. Warren FGA J.B.Nelson, Ph. D., FRMS, C.H. Winter, FGA F.Inst.E, FGA

Branch Chairmen: Midlands Branch: D.M. Larcher, FBHI, FGA North-West Branch: W Franks, FGA

Examiners: A. J. Allnutt, M.Sc, Ph.D., FGA D. G. Kent, FGA E. M. Bruton, FGA P Sadler, B.Sc, FGS, FGA C. R. Cavey, FGA K. Scarratt, FGA A. E. Farn,FGA E. Stern, FGA R. R. Harding, B.Sc, D.Phil., FGA M. Virkkunen, M.Phil., FGA E. A. Jobbins, B.Sc, C. Eng., FIMM, FGA C. Woodward, B.Sc, FGA G. H. Jones, B.Sc, Ph.D., FGA

Editor: E. A. Jobbins, B.Sc, C.Eng., FIMM, FGA Editorial Assistant: Mary A. Burland Curator: C. R. Cavey, FGA

The Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London EC1N 8SU Telephone: 071-404 3334 Fax: 071-404 8843 ^Journal of Gemmology

VOLUME 22 NUMBER FIVE JANUARY 1991

Cover Picture Two small secondary synthetic spinel 'satellites'grow from an octahedral face on the main crystal. Magnified 5x. (See 'Gemmological investigation of a synthetic spinel crystal from the Soviet Union'by J.I. Koivula, R.C. Kammerling and E. Fritsch,p.300). Photomicrograph by John I. Koivula.

ISSN: 0022-1252 258 J. Gemm., 1991, 22,

EXAMINATIONS IN GEMMOLOGY1991 Refresher Courses The courses outlined below aim particularly to help gemmology students who will be sitting their Diploma Examinations, but one course also caters for the Preliminary Examinations. The tutorials, which may extend over one, two or three days (as set out below), usually include mock practical examinations. Some courses provide tuition only, whereas others include meals and accommodation. NATURAL HISTORY MUSEUM (formerly Geological Museum), South Kensington, London. 6-7 April, 13-14 April, 20-21 April Tutors: Various GA/GTL lecturers Details: 071-404 3334 GENESIS Epsom, Surrey 9-10 May, 30-31 May, 6-7 June, 13-14 June Tutors: Colin Winter, Hilary Taylor Details: 03727 42974 or 071-404 3334 HATTON GARDEN AREA London 11 June (Preliminary), 12-13 June (Diploma) Tutors: Michael O'Donoghue, Peter Read Details: R. Huddlestone, 071-404 5004 NELSON GEMMOLOGICAL INSTRUMENTS Sundays around Easter (provisional) Tutorials at various venues depending upon demand. Topics include four difficult Cs - crystallography, chemistry, colour and cut. Tutor: Jamie Nelson Details: 071-435 2282 or 071-435 0331 WEST DEAN COLLEGE near Chichester, West Sussex 7-9 June (also 2-5 November) Tutor: Peter Read Details: Sue Overman, 0243 63301 UPTON HALL Upton, Newark, Notts. 4-5 March, 6-8 March, 4-5 June, 6-7 June (also 23-24 September, 25-27 September). Course contents vary - please check. Meals and accommodation included. Tutors: Alan Hodgkinson, Pat Daly Details: Carol Moore, 071-387 6611 Examination Dates The examination dates for 1991 are as follows: GEM DIAMOND EXAMINATION: Monday 3 June EXAMINATIONS IN GEMMOLOGY: Preliminary - Tuesday 25 June Diploma Theory - Wednesday 26 June Diploma Practical - Thursday 27 June The final date for receiving examination entry forms is 31 March. J.J. Gemm.,Gemm., 1991,22,51991, 22, 5 252599

ColourColour asas a guideguide toto thethe compositioncomposition ofof scapolitescapolite fromfrom BurmBurmaa A.G. Couper A.G. Couper Department of Mineralogy, British Museum (Natural History), London* Department of Mineralogy, British Museum (Natural History), London*

TheThe PainPain collectioncollection ofof gemstonesgemstones (BM(BM 19731973,, valuesvalues andand greygrey andand colourlesscolourless specimensspecimens thethe 246-375)246-375) frofromm MogokMogok,, BurmaBurma,, bequeathebequeathedd toto thethe highest.highest. IInn betweebetweenn werweree groupsgroups ofof mauve,mauve, pink,pink, BritishBritish MuseumMuseum (Natural(Natural History)History) inin 1973,1973, isis yellow,yellow, greenish-yellowgreenish-yellow andand beigbeigee stonesstones inin orderorder ooff remarkableremarkable notnot onlyonly foforr ththee numbenumberr ofof gem-qualitygem-quality increasingincreasing refractivrefractivee indexindex andand specificspecific gravity.gravity. mineralmineral speciesspecies foundfound inin suchsuch a relativelrelativelyy smallsmall areaarea ScapoliteScapolite withwith suchsuch a rangerange ofof colourcolour hahass notnot beenbeen ofof Burma,Burma, bubutt alsoalso forfor thethe extraordinaryextraordinary rangrangee ooff foundfound atat anyany otherother locality.locality. colourcolour withiwithinn somesome ofof thethe speciespeciess oror groups.groups. AsAs a generalgeneral rulrulee thethe densitydensity ofof scapolitescapolite increasesincreases ForemosForemostt amongsamongstt ththee latterlatter iiss ththee scapolitscapolitee groupgroup witwithh ththee meionitemeionite contentcontent,, bubutt itit cancan bbee useusedd onlyonly asas whicwhichh hahass marialitemarialite (Na4AI3Si90z4CI)(Na4Al3Si9024Cl) andand meionitemeionite a roughrough guideguide toto composition.composition. PredictionPrediction ofof thethe (Ca4AI6Si60z4C03)(Ca4Al6Si6024C03) asas itsits sodium-richsodium-rich andand calcium­calcium- meionitemeionite percentagpercentagee fromfrom opticaloptical parameterparameterss isis stillstill ricrichh end-membersend-members respectively.respectively. thethe besbestt andand quickestquickest procedure,procedure, accordingaccording toto ThereThere hahass alwaysalways beebeenn muchmuch confusion sur­sur­ UlbricUlbrichh (1973),(1973), andand thethe claimclaim isis mademade thatthat estima­estima­ roundingrounding thethe nomenclaturenomenclature ofof thethe scapolitescapolite groupgroup tiontion fromfrom ththee refractivrefractivee indexindex non0 regressionregression lineline andand inin anan attemptattempt toto simplifysimplify ththee probleproblemm thethe (Ulbrich(Ulbrich 1973,1973, FigureFigure 2 andand equationsequations 5-6,5-6, TableTable 44)) CommissionCommission onon NeNeww MineralsMinerals andand NewNew MineralMineral isis accurateaccurate withinwithin ± 5 perper centcent meionitemeionite atat thethe 9595 perper NameName·ss ofof thethe InternationalInternational MineralogicalMineralogical AssoAsso­­ centcent confidenceconfidence interval.interval. ciationciation hahass approvedapproved thethe followingfollowing proposalsproposals ((P.E TheThe 0.0440.044 differencedifference betweebetweenn thethe higheshighestt andand Bayliss,Bayliss, 1987):1987):-- lowestlowest valuesvalues ofof non0 (the(the refractivrefractivee indexindex nno0 shouldshould bebe 1.1. TheThe namnamee scapolitescapolite shouldshould bebe retainedretained asas a useusedd preferentiallypreferentially overover thethe averageaverage refractivrefractivee indexindex groupgroup namnamee toto encompassencompass mineralsminerals iinn thethe nmnm (Ulbrich(Ulbrich 1973))1973)) indicatesindicates a considerableconsiderable marialite-meionitemarialite-meionite series;series; variancevariance inin compositioncomposition betweenbetween thethe colourlesscolourless andand 2.2. TheThe namesnames ofof marialitemarialite (Na4AhSi90z4CI)(Na4Al3Si9024Cl) andand ththee darkdark blueblue scapolitescapolite fromfrom Burma.Burma. TheThe factfact thatthat meionitemeionite (Ca4AI6Si60z4C03)(Ca4Al6Si6024C03) shouldshould bbee givengiven thethe compositioncomposition ofof scapolitescapolite variesvaries widelywidely waswas speciesspecies status;status; notednoted bbyy DunnDunn et at.,al., (1978)(1978) whenwhen describingdescribing gemgem 3.3. DipyreDipyre andand mizzonitemizzonite shouldshould bbee regardedregarded asas scapolitesscapolites fromfrom world-wideworld-wide localities.localities. AmongAmong thethe varietavarietall names;names; specimensspecimens useusedd forfor thatthat studystudy werweree threthreee fromfrom 4.4. WerneriteWernerite isis synonymoussynonymous witwithh scapolitescapolite andand BurmaBurma andand oneone ofof them,them, G 3674,3674, isis describeddescribed asas shouldshould bbee discarded.discarded. pinpinkk withwith 3030 peperr centcent meionitemeionite contentcontent andand havinhavingg a IntermediateIntermediate membersmembers ofof thethe seriesseries areare givengiven byby refractivrefractivee indexindex non0 = 1.558;1.558; a secondsecond specimen,specimen, R StrunzStrunz (1970)(1970) aass dipyredipyre (MagMez(Ma8Me2 - MaMasMes)5Me5) andand 11157,11157, isis lightlight yelloyelloww andand hahass 5757 peperr centcent meionitemeionite mizzonitemizzonite (MasMes(Ma5Me5 - MazMeg).Ma2Me8). Gemmologists,Gemmologists, content;content; thethe thirthirdd specimen,specimen, G 3783,3783, isis colourlesscolourless howeverhowever,, tentendd ttoo ususee onlyonly ththee end-memberend-member names,names, witwithh 7722 perper cencentt meionitemeionite contentcontent andand a refractiverefractive marialitemarialite forfor scapolitesscapolites witwithh Na>CaNa>Ca (in(in atomatom perper index,index, llon0 = 1.587,1.587, bubutt elsewhereelsewhere inin thatthat paperpaper thethe cent)cent) andand meionitemeionite forfor thosethose withwith Ca>Ca>N Naa (in(in atomatom samesame specimenspecimen isis describeddescribed asas lightlight yellowyellow.. ThisThis peperr cent)cent) (Dunn(Dunn et at.,al., 1978).1978). maymay bbee a printingprinting errorerror or,or, asas hashas beenbeen founfoundd inin thisthis WhileWhile accumulatingaccumulating datadata toto bebe useusedd whenwhen catalo­catalo­ presenpresentt study,study, somesome otherwiseotherwise colourlesscolourless oror greygrey guingguing thethe twelvtwelvee PainPain collectiocollectionn scapolitescapolite gem­gem- materialmaterial appearsappears toto havehave a veryvery faintfaint yelloyelloww tinge.tinge. stonestoness (BM(BM 1973,1973,364-375) 364-375),, itit becambecamee apparentapparent thatthat InIn orderorder ttoo obtainobtain refractivrefractivee indicesindices ofof asas manymany whewhenn theythey werewere listedlisted inin orderorder ofof eithereither increasingincreasing BurmeseBurmese scapolitesscapolites asas possiblepossible,, fivefive moremore stonesstones inin refractiverefractive index,index, nmn0, (1.(1.544-1.588 544-1. 588)) oror specificspecific gravitygravity thethe BM(NH)BM(NH) collectioncollection werewere examinedexamined andand threethree (2.60-2.72),(2.60-2.72), theythey werewere arrangedarranged alsoalso inin colourcolour fromfrom a privateprivate (A.}.)(A.J.) collection.collection. TheThe recordrecordss ooff groupsgroups withwith dark-bluedark-blue specimensspecimens havinghaving thethe lowestlowest fourteenfourteen stonesstones inin thethe formerformer InstituteInstitute ofof GeologicalGeological SciencesSciences gegemm collectioncollection providedprovided additionaladditional data,data, ·Present^Present address:address: Henfie/d,Henfield, WestWest Sussex Sussex althoughalthough inin thethe casecase ofof thethe cabochon-cutcabochon-cut stonesstones

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Fig. 2. A sserieeriess ofof chatoyamchatoyant scapolites fromfrom Burma.. TheThe keykey numbersnumbers relaterelate toto TableTable I.1. Photo AlanAlanJobbins Jobbins..

25 34 14

16 4 3 22 20 23

Fig.. 3. A serieseriess ooff facetefacetedd scapolitess frofromm BurmaBurma.. ThThee keykey numbernumberss relatrelatee ttoo TablTablee 1I.. Photo AlanAlanJobbins. Jobbins. 262 J. Gemm., 1991, 22, 5 both refractive indices could not readily be deter­ three from the private (A.J.) collection were obtai­ mined. The refractive indices of the large cabochon- ned by weighing them in ethylene dibromide and cut stones in the BM(NH) collection were obtained correcting for temperature. by scraping a very small amount of powder from The thirty-four scapolite stones from Burma around the girdle and measuring in sodium light used in this study are listed (Table I) in order of using mixtures of paraffin oil and a-mono- increasing specific gravity, together with their col­ bromonaphthalene as immersion media, the values our and refractive indices if known. As it has been of which were checked on a Bellingham and Stanley shown by Ulbrich (1973) that a close estimation of refractometer. Faceted stones were measured on a meionite percentage in scapolite can be made from Rayner refractometer in sodium light and, in the the refractive index n0, these two values (per cent case of the small cabochon-cut stones, a 'rough' meionite and n0) have been related using the measurement was obtained on a Rayner refracto­ regression line calculated by Ulbrich (1973) Figure meter using the 'distant vision' or 'spot' method 2, and plotted against specific gravity (Figure 1). A described by Lester Benson (1948). The specific scale snowing the colours of the stones has been gravities of the seventeen BM(NH) stones and the introduced to show the apparent relationship with

TABLE 1: Colours and optical data of some gem scapolites from Burma listed in order of specific gravity.

S.G. nD ne 1. MI 35774 Faceted Violet , Burma (?) 2.59 1.544 1.538 2. BM. 1973,374 Cabochon Deep-blue Mogok 2.60 1.55* 3. MI 35519 Faceted Purple-blue Burma 2.60 1.549 1.539 4. BM. 1973,370 Faceted Deep-blue Mogok 2.61 1.548 1.538 5. BM. 1973,375 Cabochon Deep-blue Mogok 2.61 1.55* 6. BM. 1966,296 Cabochon Pink Mogok 2.62 1.557 1.543 7. MI 28939 Cabochon Pink Mogok 2.63 — — 8. BM. 1973,367 Cabochon Pink Mogok 2.63 1.55* 9. BM. 1933,97 Cabochon Pinkish-grey Mogok 2.63 1.558 1.543 10. BM. 1912,684 Cabochon Pink Mogok 2.63 1.557 1.546 11. A J. 0.1792 Cabochon Pale-pink Mogok 2.63 1.56* 12. AJ.0.2952 Cabochon Mauvish-blue Mogok 2.63 1.56* 13. BM. 1966,295 Cabochon Pink Mogok 2.63 1.557 1.545 14. BM. 1973,368 Faceted Pink Mogok 2.63 1.559 1.543 15. MI 35518 Cabochon Pink Burma 2.63 — — 16. MI 35522 Faceted Pale-pink Burma 2.63 1.557 1.542 17. BM. 1973,366 Cabochon Pinkish-grey Mogok 2.64 1.56* 18. BM. 1912,683 Cabochon Pink Mogok 2.64 1.560 1.546 19. MI 28940 Cabochon Pink Mogok 2.64 — — 20. MI 30205 Faceted Pink Mogok 2.64 1.557 1.540 21. MI 30211 Cabochon Blue Mogok 2.64 — — 22. MI 35521 Faceted Pink Burma 2.64 1.561 1.544 23. MI 35520 Faceted Pale-blue Burma 2.65 1.557 1.541 24. MI 35524 Cabochon Pale greyish-green Burma 2.67 — — 25. BM. 1973,369 Faceted Pink Mogok 2.67 1.568 1.545 26. MI 28938 Cabochon White Mogok 2.68 — — 27. MI 30206 Cabochon Pale-buff Mogok 2.68 — — 28. BM. 1973,372 Cabochon Pale-yellow Mogok 2.68 1.575 — 29. BM. 1973,373 Cabochon Greenish-yellow Mogok 2.69 1.580 — 30. BM. 1973,365 Cabochon Beige Mogok 2.70 1.574 1.552 31. BM. 1973,364 Faceted Colourless Mogok 2.70 1.580 1.550 32. BM. 1973,371 Cabochon Grey Mogok 2.72 1.588 — 33. AJ. 1.6908 Rough Colourless Mogok 2.72 1.588 1.557 34. MI 31629 Faceted Colourless Burma 2.72 1.585 1.554 ^Obtained by 'distant vision' method. 'MF numbers refer to :specimen s in the collection of the Institute of Geological Sciences (IGS). J. Gemm., 1991, 22, 5 263

composition. Optical values obtained by the 'dis­ yellow tinge. The next group on Figure 1 is at 72 to tant vision' method have not been used in the 76 per cent meionite and consists of a grey stone, preparation of this graph. with a very faint hint of yellow, and a colourless It is interesting to note that the colours, refractive stone. indices and composition of the three Burma scapo- This study has shown that by using the refractive lites used by Dunn et al. (1978) and referred to index, n0, to estimate the meionite content of eight above, fit comfortably on to the graph (Figure 1). of the Pain scapolites, and then using colour and The wide range of composition of Burmese material specific gravity as guides in the case of the remain­ shown by Dunn et al. (1978) to be from 30 per cent ing four, it is possible to classify the dark-blue meionite for the pink stone, to 72 per cent meionite scapolite as marialite, the pink as marialite (variety for the colourless stone, now appears from this dipyre) and the pale-yellow, greenish-yellow, beige, study to be even greater, with the meionite content grey and colourless stones as meionite (variety estimated to be 10-17 per cent for the group of mizzonite). violet, deep-blue and purplish-blue stones and 72-76 per cent for the group of grey and colourless Acknowledgements: stones. It must be noted, however, that there is some The author is indebted to Alan Jobbins for the doubt about the locality of IGS 35774, the violet loan of three stones from his private collection. stone with the lowest estimated meionite content at 10 per cent, but it is thought most likely to come from Burma. The largest group consists mainly of References pink stones with a few pale-blue or mauve amongst Bayliss, P., 1987. Mineralogical Magazine, 51, 1, 176. them and their estimated meionite content ranges Benson, L., 1948. Refractive indices of cabochon cut stones. from 30 to 35 per cent. Apart from a lone pink stone Gems and Gemology, 6, 2, 35-8, 58. Dunn, P.J., Nelen, J.E., Norberg, J., 1978. On the composition at about 45 per cent meionite there is a large gap of gem scapolites. Journal of Gemmology, XVI, 1, 4. from about 35 to 55 per cent meionite when blue Strunz, 1970. Mineralische Tabellen, 5ed, Geest and Portig K-G, disappears as a background colour and yellow Leipzig. appears to be the main influence in the body colour Ulbrich, H.H., 1973. Crystallographic data and refractive of the stones. From about 55 to 65 per cent meionite indices of scapolites. American Mineralogist, 58, 81-92. the stones are beige, pale-yellow, greenish-yellow [Manuscript received 5 January 1990; revised 19 August and an almost colourless stone with a very faint 1990.] 264 J. Gemm., 1991, 22, 5

'Machingwe': A new emerald deposit in Zimbabwe Jan Kanis*, Charles E.S. Arps** and Pieter C. Zwaan**

*Cascais, Portugal **National Museum of Natural History, Department of Mineralogy and Petrology, PO Box 9517, 2300 RA Leiden, The Netherlands

Abstract The Greenstone Belts are elongated or irregular Geological and gemmological details of a promising shaped bodies of steeply dipping, (partly) tightly new emerald deposit in the Mweza Range Greenstone folded, generally schistose rocks. Their length may Belt of southern Zimbabwe are discussed and compared reach a few hundred kilometres. with data from Sandawana and other nearby emerald deposits. Geology of the Zimbabwean Greenstone Belts Introduction Stratigraphically the Zimbabwean greenstone In May 1987 the first author was fortunate formations can be subdivided into three divisions, enough to have the opportunity to pay a short visit respectively the Sebakwian, Bulawayan (2700-2600 to a newly discovered emerald occurrence in Zim­ Ma) and Shamvaian Supergroups. They are com­ babwe, named 'Machingwe deposit', thanks to the posed of ultramafic, mafic to felsic intrusive and kind permission granted by the owner, Mr C.C. volcanic rocks, such as peridotites, basalts (pillow Chigumba, and with the assistance of the Mineral lavas), andesites and rhyolites, with intercalations Marketing Corporation of Zimbabwe. This Cor­ of sedimentary rocks (conglomerates, pelite, poration is a state controlled department based in banded iron formation, limestones, etc.). Harare. It channels, on a non-profit basis, all The older Sebakwian and to a lesser extent the gemstone and mineral sales from producers to Bulawayan are mainly volcanic deposits with inter­ world markets. The Corporation also acts as an calations of meta-sedimentary rocks, while the advisory body to the small operator. younger Shamvaian Supergroup is largely repre­ sented by metamorphic clastic deposits. These Geotectonic setting volcano-sedimentary deposits seem to have covered With the exception of Palaeozoic mountain belts large areas of the Archaean crust. along the northwestern and southern margins, the The Zimbabwean and other greenstone forma­ African continental crust developed during the tions in the world have been intensively investigated Precambrian. The major structural units of central (see Windley, 1977). With respect to the stratigra­ and southern Africa can be subdivided into two phy, volcanic geochemistry and structural appear­ cratonic blocks that were stabilized since middle ance they are remarkably similar. Furthermore they Proterozoic times (about 1100 Ma) and are sepa­ are always surrounded by older gneisses and youn­ rated from each other by the so-called Pan-African ger, partly intrusive, granitoid plutons, and nearby Mobile Belts (Damara, Zambezi and Mozambique high-grade metamorphic terrains. Mobile Belts - about 550 Ma in age). Within the The Zimbabwean Archaean basement rocks cratons several older Archaean cratons occur, with underwent a low-grade regional metamorphism. ages of 2500 Ma and older, of which the Rhodesian The (ultra)mafic rocks recrystallized into upper- Craton (Figure 1) is of special importance in the greenschist facies to lower amphibolite fades present study. 'greenstones'. Current rock-types of the Greenstone The Rhodesian Craton stabilized at about 2550 Belts are serpentinites, talc schists, chlorite schists, Ma; it is surrounded by the Zambezi and Mozambi­ tremolite-chlorite schists, hornblende schists, phyl- que Mobile Belts in the north and east respectively, lites and quartz-mica schists. and the Early Proterozoic Limpopo Mobile Belt Specific higher-temperature exceptions occur (about 1850 Ma) in the south. The cratonic base­ near the contacts with the younger granites and the ment consists of older gneisses, a variety of schist large number of pegmatitic off-shoots. In these belts, better known as Greenstone Belts, and youn­ environments, especially at the contacts with the ger (gneissic) granites and pegmatites. ultramafic schists, pegmatoid impregnations under

© Copyright the Gemmological Association ISSN: 0022-1252 J.J. Gemm.,Gemm., 1991,22,51991, 22, 5 262655

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10

Fig.Fig. I.1. DistributionDistribution ofof thethe PrecambrianPrecambrian geotectonicgeotectonic unitsunits inin centralcentral andand southernsouthern Africa.Africa. highhigh pressurepressure (pneumatolitic)(pneumatolitic) werewere responsibleresponsible forfor TheThe maficmafic anandd ultramafiultramaficc rockrockss ofof greenstonegreenstone restrictedrestricted butbut intenseintense contact-metasomaticcontact-metasomatic reac­reac­ beltsbelts areare welwelll knownknown supplierssuppliers ofof mineraminerall oresores tionstions alteringaltering thethe ultramaficultramafic rocksrocks intointo biotitebiotite andand containingcontaining thethe economicallyeconomically importantimportant elementselements biotite-phlogopitebiotite-phlogopite schists.schists. A similarsimilar lithologylithology hashas likelike chromium,chromium, cobalt,cobalt, nickelnickel,, coppercopper,, zinczinc,, silver,silver, beenbeen reportedreported fromfrom otherother emerald-producingemerald-producing areasareas gold,gold, manganesemanganese anandd iron.iron. InIn earlieearlierr daysdays green­green­ (Martin,(Martin, 1962;1962; SliwaSliwa & Nguluwe,Nguluwe, 1984;1984; SchwarzSchwarz & stonestone beltsbelts werweree callecalledd 'gold'gold belts'belts:. Eidt,Eidt, 1989).1989). ChromiumChromium andand nickenickell areare mainlmainlyy restricterestrictedd toto thethe TheThe formationformation ofof phlogopitephlogopite tooktook placeplace accord­accord­ ultramaficultramafic rocksrocks,, i.e.i.e. serpentinitesserpentinites anandd talctalc schistsschists inging toto thethe mineralmineral reactionsreactions (1)(1) alkalialkali feldsparfeldspar ++ (Martin,(Martin, 1962;1962; Windley,Windley, 1977;1977; MetsoMetsonn & Taylor,Taylor, serpentineserpentine = phlogopitephlogopite + talctalc + waterwater,, andand (2)(2) 1977).1977). ThisThis fact,fact, inin combinationcombination witwithh extensiveextensive alkalialkali feldsparfeldspar + talctalc = phlogopitphlogopitee + quartz,quartz, whilewhile intrusionsintrusions ooff beryllium-bearinberyllium-bearingg pegmatitespegmatites,, hahass inin thethe appearanceappearance ofof biotitebiotite insteadinstead of,of, or,or, inin additionaddition severalseveral placeplacess leadlead ttoo thethe fortuitoufortuitouss crystallizationcrystallization toto phlogopitephlogopite dependeddepended onon thethe originaloriginal ironiron contentcontent ofof emeraldsemeralds atat,, oror adjacenadjacentt to,to, thethe contactscontacts ofof thethe ofof thethe ultraultrabasi basicc rockrock (Schwarz(Schwarz & Eidt,Eidt, 1989).1989). pegmatiticpegmatitic impregnationimpregnationss witwithh ththee greenstones.greenstones. N 0'> 0'> ~ 3 " ~ ~ Cl - V> N

J. ':- Gemm., 1991,22,5 266 J"" 21°5 ) a) i .", esia, craton ingwc l Stars Victor rv (Be bells greenstone Rhod anei~ses b e WI. of Twin da I "-J go ~~rv min an n ~ :"lkholson Rhodesian ­ llo rv l Map dykes l husi fe of ca­ ) al . hikw ila lachingwe d ' ~'V~ ( Dvke) rocks Mayfield l\1asvi Nove Bikila Wes F Mberengwa C :'> Sandawana an ogic l dary 10 7 3 9 8 :! 5 (i .t s metavol­ eo un nl G mt:l:wol Great fic ultramafic bo a me -? granites ! ~ i porphyritic m afic lic v rocks i etavolcanic l __ '" n mll ased rocks m r nic c , olcr ic parlly outhern Provisional inclllding ( Ilwi lI~t met c1 IIl ca ( YOllnger s s _ the + + m ' . o A ~ A. Limpopo 20 the to Craton, n ~O~ a o' o adjacent E 0 n Rhodesi 30 ato r the c ' of esian od Rocks c i Rh ' it the Gran of the pan of ap M southern ional s i the of rov P ap e m th ical and , 1 97 1 Geolog rv 2. Fig. J. Gemm., 1991,22,5 267

Fig. 3. The hills of the Mweza Range Greenstone Belt covered by dense bush; a bulldozer has been operating near the No. 3 shaft (1987).

The geological sketchmap of Figure 2 shows the however, since the Sandawana emeralds on the Zeus southern part of the Rhodesian Craton in juxtaposi­ claims, is a new occurrence approximately 12 km tion with the high-grade Limpopo Mobile Belt. NE of the Sandawana mine, along the Mweza Both units are separated by the 'pyroxene isograd', Range, which is named 'Machingwe' mine, after a which is arbitrarily the northern boundary of the nearby stream. Limpopo Mobile Belt. The presence of emerald in the Mweza Range A striking feature on the map, southwest of Greenstone Belt is connected with the pegmatitic Masvingo (previously Fort Victoria) and very close intrusions derived from the younger Chibi granite to the southern contact, is a narrow NE-SW batholith. The metasomatic rocks at the contact of trending 140 km long belt. This is the Mweza the pegmatoids and the (ultra)mafic rocks, i.e. the (Range) Greenstone Belt, consisting of volcano- biotite and biotite-phlogopite schists, are the main sedimentary deposits belonging to the Bulawayan host-rocks of the emeralds. But, as a result of Supergroup, more or less adjacent to the elongated contamination of the pegmatoid material, this gem- Chibi granite batholith. stone is also present in the adjacent pegmatite.

The emerald occurrences The Machingwe Emerald mine In May 1957 (Bohmke, 1982) the renowned The car journey from Masvingo to the Mashing- Sandawana emerald deposit was discovered. Since we mine takes about 3l/z hours. The first 135 km is a then a number of other minor emerald occurrences well-kept tarred road, passing various important have been discovered within the southern part of asbestos mines exploited in the serpentinites of the the Rhodesian Craton, such as the localities Novel- Zvishavana (Shabani) district. Thereafter, the jour­ lo, Twin Star, Chikwanda, Mayfleld, Popoteke and ney has to be continued over a 55 km very rough Renders in the Masvingo Greenstone Belt and gravel road and only 4-wheel drive vehicles will be Mustard and others in the Filabusi Greenstone Belt able to pass. (Anderson, 1976, 1978; Martin, 1963). The vegetation of the Mweza Range greenstone The most important emerald discovery to date, hills is quite dense (Figure 3) and in sharp contrast 268268 J.J. Gemm.,Gemm., 1991,22,51991, 22, 5

toto thethe surroundingsurrounding almostalmost barrebarrenn graniticgranitic rocksrocks pegmatitepegmatite is~jis mined, whieb.which hashas widenedwidened herehere toto withwith thornythorny bushebushess andand littlelittle grassgrass.. 3'/2m31/2m andand isis d1~mgrutydipping slightly south.south. TheThe emeraldemerald AmphibolitAmphibolitee schistsschists areare thethe predominanpredominantt rock­rock- productioproductionn camecame mainlmairuyy frQtnfrom ththee No.3No. 3 shaft.shaft. AlsoAlso typtypee oonn thethe MachingweMachingwe claimsclaims andand variouvariouss pegma­pegma­ thethe firstfirst emeraldsemeralds foottttmmltateafound in the area werewere discovereddiscovered tites,tites, aplites,aplites, quartz-feldsparquartz-feldspar andand feldsparfeldspar veinveinss andand inin thethe samesame placeplace wheMlateroowhere later on thethe No.3No. 3 shaftshaft waswas quartzquartz stringersstringers havehave intrudedintruded thesthesee amphibolites.amphibolites. sunk.sunk. EmeraldEmerald iiss presenpresentt inin thethe schistschistss aass welwelll aass inin thethe ApartApart frofromm producingproducing oreore from.from ththee threthreee pros­pros­ felsicfelsic rocksrocks (Figure(Figure 4)4).. pectinpectingg shafts,shafts, allall mininminingg hahass beenbeen carriedcarried outout bbyy TheThe firstfirst emeraldsemeralds ofof thethe MachingweMachingwe streamstream areaarea openopen castcast method.method. TwoTwo bulldozersbulldozers werweree clearingclearing thethe werweree foundfound inin DecemberDecember 19841984 andand thethe officialofficial namename overburdenoverburden andand wastewaste rock.rock. NotNot onlyonly wawass thethe forfor thethe minminee becambecamee 'Machingwe'Machingwe SyndicateSyndicate NoNo.2. 2 miningmining basebasedd onon veryvery simplesimple methodsmethods atat thethe timetime Mine:Mine', butbut isis betterbetter knownknown undeunderr thethe namename thethe minemine waswas visited,visited, butbut alsoalso thethe plantplant andand thethe MachingweMachingwe mine.mine. treatmenttreatment ofof thethe emerald-bearingemerald-bearing rocrockk wawass veryvery AtAt thethe timetime ofof thethe firstfirst author'sauthor's visivisitt toto thethe minemine basic.basic. A smallsmall screeningscreening trommeltrommel was thethe onlyonly thethe NoNo.1. 1 shaftshaft waswas sunksunk onon aa 3m 3m widewide NN- -SS striking,striking , mechanizedmechanized equipmentequipment whilwhilee allall otherother worworkk was steeplysteeply dippingdipping pegmatitpegmatitee (Figure(Figure 5)5) toto a depthdepth ofof donedone bbyy hand.hand. 21m21m wherewhere thethe watewaterr tabletable waswas struck.struck. JustJust aboveabove TheThe emeraldemerald potentialpotential ofof thisthis occurrence,occurrence, howev­howev­ thisthis levellevel isis a 15m15m longlong adit.adit. er,er, appearsappears toto bbee largelarge andand thethe factfact thatthat thethe nearbynearby ApproximatelyApproximately 150m150m NNWW ofof thethe No.1No. 1 shaftshaft isis thethe SandawanaSandawana mine,mine, afterafter mormoree thathann thirtthirtyy yearsyears,, stillstill No.No.22 oror 'Mahonde''Mahonde' shaftshaft withwith a depthdepth ofof 15m.15m. TheThe produceproducess emeraldsemeralds ofof goodgood quality,quality, eveneven atat theirtheir neanearr verticalvertical pegmatitpegmatitee minedmined herehere isis aboutabout 2m2m widewide deepestdeepest levellevel ofof 150m,150m, makesmakes ththee MachingweMachingwe minemine andand iiss strikingstriking E-W. ThisThis well-developewell-developedd pegmatitepegmatite even'moreeven more interestininterestingg asas thethe geologicalgeological conditionsconditions hahass a numbernumber ofof interestinginteresting apophysesapophyses whichwhich areare areare likellikelyy toto bebe similar.similar. emerald-bearingemerald-bearing (Figure(Figure 6).6). A furtherfurther 60m60m E ofof thethe InIn thethe paspastt beryberyll was a ververyy importantimportant strategicstrategic No.No.22 shaftshaft isis thethe verticaverticall No.3No.3 shaft,shaft, wherewhere thethe samesame mineralmineral,, andand ZimbabweZimbabwe waswas ththee world'sworld's secondsecond

Fig.4(a)Fig. 4(a) Fig.4(b)

Fig.4(c)Fig. 4(c) Fig.4(d) Fig.Fig. 4.4. Thin-sectionThin-section photomicrographphotomicrographss ofof emerald-bearingemerald-bearing amphiboliticlibolitic schistschist (a)(a) andand (b)(b) andand pegmatitpegmatitee (c)(c) andand (d).(d). NoteNote thethe presencepresence ofof actinoliticactinolitic inclusionsinclusions inin ththee metablasticmetablastic emeraldsIds ofof thethe amphiboliteamphibolite inin contrastcontrast toto ththee inclusion-freeinclusion-free euhedraleuhedral emeraldemerald crystalscrystals ofof thethe pegmatite.pegmatite. J. Gemra., 1991, 22, 5 269

Fig. 5. A 15m long adit in emerald-bearing pegmatite near the Fig. 6. Large emerald crystals, above coin, in pegmatite No.l shaft (1987). apophysis near the No.3 shaft. The adjacent altered zone consists of serpentinite, biotite-, tremolite-, and talc schists.

.:.; **i ",...

•*&Z$rvJ'.rl

Fig. 7. Parcel containing small emerald crystal fragments. Mag. 2x. 270270 J.J. Gemm.,1991,22Gemm., 1991,22,5, 5 largestlargest producerproducer withwith berylberyl occurringoccurring inin manymany TableTable 1:1: QuantitativeQuantitative geochemicageochemicall analysesanalyses ofof localities.localities. ThisThis circumstance,circumstance, combinedcombined withwith thethe AfricanAfrican emeralds.emeralds. factfact thatthat specificspecific rock-typesrock-types ofof thethe manymany GreenstoneGreenstone BeltsBelts areare chromium-bearing,chromium-bearing, makesmakes itit veryvery possiblepossible thatthat furtherfurther emeraldemerald discoveriesdiscoveries ofof notenote maymay yetyet bebe 'Machingwe''Machingwe' SandawanaSandawana MikuMiku mademade inin Zimbabwe.Zimbabwe. 1 2 2 3 4 5

Si02 67.4267.42 67.167.111 65.065.000 63.8 63.844 62.2362.23 PropertiesProperties ofof thethe MachingweMachingwe emeraldsemeralds AlA122003 13.6013.60 12.8112.81 15.5015.50 18.0618.06 15.4115.41 TheThe colourcolour huehue ofof thethe MachingweMachingwe emeraldemerald isis a FeFe totaltotal 0.70.766 0.80.866 0.500.50 0.300.30 0.10.111 superbsuperb emeraldemerald green,green, includingincluding thethe smallestsmallest 'pin­'pin- MgOMgO 2.652.65 3.03.000 3.003.00 0.70.755 0.70.766 head'head' sizes,sizes, andand theirtheir brilliancbrilliancee isis magnificent,magnificent, veryvery MnOMnO — — 0.00.022 similarsimilar toto thethe SandawanaSandawana emeralds.emeralds. MostMost emeraldsemeralds CaOCaO 0.00.055 0.0 0.055 — — 0.30.311 areare ratherrather small,small, brokenbroken piecespieces (Figure(Figure 7).7). Well­Well- NazONa20 2.212.21 2.22.288 2.02.000 2.02.033 2.632.63 developeddeveloped crystalscrystals werewere onlyonly seenseen inin thethe finefine KzOK20 0.00.044 0.00.033 — 0.00.055 2.892.89 graingrain-sizes -sizes.. Li2200 0.10.155 0.10.100 — TheThe largestlargest facetedfaceted andand veryvery cleanclean MachingweMachingwe BeOBeO 11.2411.24 11.8811.88 13.6013.60 13.2813.28 11.9011.90 emeraldemerald waswas jusjustt underunder 5 caratscarats inin weight.weight. TheThe bulkbulk CrZ03Cr 0 0.500.50 0.60.600 0.30.333 ofof thethe facetedfaceted stonesstones is,is, however,however, underunder oneone carat.carat. 2 3 CszOCs20 0.00.044 0.00.044 — — — GoodGood qualityquality cabochoncabochon cutcut emeraldsemeralds occuroccur inin muchmuch HzO+H20+ — — — 1.071.07 2.592.59 largerlarger sizes.sizes. HzO-H20- — — — — 0.060.06 TheThe chemicalchemical compositioncomposition ofof a palepale greengreen andand a deepdeep greengreen emeraldemerald samplesample ofof MachingweMachingwe minemine waswas TotalTotal 98.098.011 98.0698.06 100.25100.25 100.08100.08 99.2499.24 analysedanalysed byby atomicatomic absorptionabsorption spectrometryspectrometry (AAS)(AAS) andand inductivelyinductively coupledcoupled plasmaplasma spectrometryspectrometry SrSr 6.06.0 4.04.0 (ICPS)(ICPS) methods.methods. TheThe resultsresults areare listedlisted inin TableTable 1I.. TiTi 39.39.00 32.032.0 TheThe chemicalchemical datadata fromfrom twotwo SandawanaSandawana emeraldemerald CoCo 113.0113.0 111.0111.0 samplessamples havehave beenbeen added.added. TheThe latterlatter results,results, howev­howev­ MnMn 173.0173.0 286.286.00 er,er, werewere obtainedobtained byby differentdifferent methodsmethods inin differentdifferent P 61.061.0 48.48.00 periodsperiods andand shouldshould thereforetherefore bebe evaluatedevaluated withwith care.care. V 192.0192.0 213.213.00 TheThe mostmost noticeablenoticeable differencesdifferences withwith thethe Sanda­Sanda­ ZnZn 66.66.00 49.49.00 wanawana materialmaterial areare thethe contentscontents ofof chromium,chromium, beryl­beryl­ LiLi 730.0730.0 637.0637.0 liumlium andand iron.iron. PartPart ofof magnesium,magnesium, sodiumsodium andand NiNi 30.030.0 38.38.00 lithiumlithium shouldshould bebe attributedattributed toto thethe influenceinfluence ofof CrCr 1800.01800.0 3970.3970.00 inclusionsinclusions (B6hmke,(Bohmke, 1982).1982). TheThe refractiverefractive indicesindices andand densitiesdensities ofof a numbernumber ofof MachingweMachingwe emeraldsemeralds werewere determined,determined, givinggiving MainMain elementselements araree inin Wt.%Wt. %,, tractracee elementselements iinn ppm.ppm. thethe followingfollowing (average)(average) results:results: Nos.Nos. 1 andand 2:2 : resp.resp. greengreen andand deepdeep greengreen emeraldsemeralds fromfrom 'Machingwe', analysis by ICP (Induced Coupled Plasma) and NeNe 1.584-1.5861.584-1.586 andand NoN0 1.589-1.591.589-1.5933 (eleven(eleven samples)samples) 'Machingwe', analysis by ICP (Induced Coupled Plasma) and birefringencebirefringence 0.006-0.0080.006-0.008 AASAAS (Atomic(Atomic AbsorptioAbsorptionn Spectrometry)Spectrometry) methodsmethods,, AnalyticalAnalytical 3 GeochemicalGeochemical Lab.Lab. (analyst:(analyst: Mrs.Mrs. Ir.Ir.T.G.Djie-Kwee) T. G. Djie-K wee),, Inst.Inst. densitydensity 2.7612.761 g/g/cmcm3 (eight(eight samples)samples) EarthEarth Sci.,Sci., StatStatee UniversitUniversityy atat UtrechtUtrecht,, TheThe Netherlands;Netherlands; A numbernumber ofof refractiverefractive indexindex measuremensmeasuremens ofof thethe No.3:No. 3: emeraldemerald fromfrom Sandawana,Sandawana, datdataa fromfrom Biihmke,Bohmke, 19821982,, MachingweMachingwe emeraldsemeralds havehave beenbeen putput togethertogether withwith modifiedmodified afteafterr GubelinGiibelin,, 19581958;; thethe datadata fromfrom otherother ZimbabweanZimbabwean emeraldsemeralds inin a No.4:No.4: emeraldemerald fromfrom Chingachura,Chingachura, neanearr Sandawana,Sandawana, wet­wet- chemical,chemical, spectrographicspectrographic anandd flame photometriphotometricc methodsmethods,, datadata diagramdiagram (Figure(Figure 8)8) asas was previouslypreviously publishedpublished byby fromfrom Martin,Martin, 1962;1962; AndersonAnderson (1978).(1978). No.5:No. 5: emeraldemerald fromfrom MikuMiku (Kafub(Kafubuu area,area, Zambia)Zambia),, datadata fromfrom AlthoughAlthough a deepdeep redred colourcolour underunder thethe ChelseaChelsea SliwaSliwa & Nguluwe,Nguluwe, 19841984.. colourcolour filterfilter was toto bebe expected,expected, itit turnedturned outout toto bebe a dulldull red,red, andand notnot reallyreally veryvery bright.bright. ThisThis maymay bebe duedue toto a lowerlower chromiumchromium contentcontent andand a higherhigher ironiron contentcontent thanthan emeraldsemeralds fromfrom SandawanaSandawana (see(see TableTable thethe samplessamples witwithh ththee finesfinestt colourscolours,, araree easileasilyy seen,seen, 1).1). eveneven withwith ththee simplestsimplest hanhandd spectroscope.spectroscope. UnderUnder ultra-violetultra-violet lightlight thethe emeraldsemeralds areare brightbright TheThe propertiepropertiess ooff thethe emeraldemeraldss presenpresentt inin thethe green;green; thethe shortshort wavewave conditionsconditions ofof a lesserlesser intensi­intensi­ felsicfelsic rocksrocks oror thethe schistsschists araree slightlyslightly differentdifferent withwith tyty,, betterbetter describeddescribed asas greenishgreenish only.only. respecrespectt ttoo colourcolour,, i.ei.e.. chromiuchromiumm contentcontent,, andand TheThe absorptionabsorption spectrumspectrum isis veryvery distinct.distinct. Chro­Chro­ inclusions.inclusions. miummium lineslines inin thethe redred andand a strongstrong bandband inin thethe AsAs a generagenerall rulrulee ththee MachingweMachingwe emeraldemeraldss withinwithin yellow-greenyellow-green partpart ofof thethe spectrum,spectrum, particularlyparticularly inin thethe pegmatitespegmatites areare ooff a lighterlighter greengreen huehue thanthan thethe J.J. Gemm.,Gemm., 1991,22,51991,22,5 271271

1.6001.600 T 9 8 00/? 7

6 1.595

4

3 2

1.590

9

8

nO 7

6 1.585

4

3

2

1.580

9 MasvingoMasvingo (Fort(Fort Victoria)Victoria) areaarea 8 ()• MwezaMweza GreenstoneGreenstone BeltBelt @ FilabusiFilabusi GreenstonGreenstonee BeltBelt 7 otherother areaareass 6 ~ 'Machingwe''Machingwe' minemine (Mweza(Mweza Range)Range) 1.575 2 3 4 III 6 7 8 9 2 3 4 It! 7 9 ,.... i 110 e » ~~8 ~ ~ ~ " ~ -' nnEE Fig.Fig. 8.8. RefractiveRefractive indicesindices andand birefringencbirefringencee ooff ZimbabweanZimbabwean emeralds.emeralds. DataData fromfrom Anderson,Anderson, 1978,1978, andand thethe presenpresentt study.study. poikiloblast-typpoikiloblast-typee inin thethe adjacentadjacent (ultra)mafi(ultra)maficc rockrock ofof actinolite/tremoliteactinolite/tremolite needles,needles, oror atat leastleast longlong ofof thethe alteredaltered zonezone.. prismaticprismatic palpalee yellowisyellowishh toto brownishbrownish crystalscrystals ooff OnOn thethe otherother hanhandd thethe pegmatitpegmatitee emeraldsemeralds areare somesome membermember ofof thethe amphiboleamphibole group,group, eithereither relativelrelativelyy freefree ofof inclusionsinclusions,, inin contrastcontrast toto thethe clusteredclustered togethertogether asas wellwell asas individualindividual crystalscrystals emeraldsemeralds fromfrom thethe alteredaltered zone.zone. MicroscopicMicroscopic invesinves­­ pointedpointed inin differentdifferent directions.directions. tigatiotigationn ofof thethe inclusionsinclusions revealsreveals (Figure(Figure 9),9), asas InIn somesome ofof thethe specimensspecimens flake-likeflake-like inclusionsinclusions expected,expected, a greatgreat similaritysimilarity toto thethe SandawanaSandawana cancan bebe seen,seen, ververyy likelylikely consistingconsisting ofof colourlesscolourless toto emeralds,emeralds, whichwhich isis demonstrateddemonstrated bbyy anan abundanceabundance lightlight brownbrown,, distinctlydistinctly pleochroipleochroicc mica.mica. 272272 J.J. Gemm.Gemm.,, 1991,22,51991,22,5

Fig.9(a) Fig.9(b)

Fig.9(c)Fig. 9(c) Fig.9(d)Fig. 9(d) Fig.Fig. 9.9. TypicalTypical inclusionsinclusions inin emeraldsemeralds fromfrom thethe 'Machingwe''Machingwe' mine:mine: actinolite/tremoliteactinolite/tremolite needleneedless eitheeitherr (a(a)) denselydensely accumulatedaccumulated (crossed(crossed nicols),nicols), (b)(b) radiallyradially orientedoriented oror (c)(c) atat random;random; (d)(d) finefine needleneedle witwithh somesome micmicaa flakesflakes (crosse(crossedd nicols).nicols).

ReferencesReferences Anderson,Anderson, S.M.,S.M., 1976.1976. A notenote onon thethe occurrenceoccurrence ofof emeraldemerald atat Phaup,Phaup, A.E.,A.E., 1973.1973. The granitic rocks of the Rhodesian craton. Mayfield Farm,Farm, Fort Fort Victoria, Victoria, Rhodesia. Rhodesia. Journal Journal of Gemmology, of Gem­ Geol.Geol. Soc.Soc. SouthSouth AfricaAfrica,, SpecSpec.. Pub!.Publ. nrnr.. 3 (Symposiu(Symposiumm onon mology, 15,2,15, 2, 80-82.80-82. granites,granites, gneissegneissess anandd relaterelatedd rocks)rocks),, 59-6759-67.. Anderson, S.M., S.M., 1978. 1978. Notes Notes on on the the occurrence occurrence and andmineralogy mineralogy Schwarz,Schwarz, D.,D., Eidt,Eidt, T.T.,, 1989.1989. ThThee BrazilianBrazilian emeraldemeraldss anandd theirtheir ofof emeraldsemeralds inin Rhodesia.Rhodesia. Journal of Gemmology, 16,16, 3,3, occurrences:occurrences: CarnaibaCarnaiba,, Bahia.Bahia. Journal of Gemmology,Gemmology, 21,21, 88,, 177-85.177-85. 474-94.474-94. Biihmke,Böhmke, Fe.,F.C., 1982.1982. EmeraldsEmeralds atat Sandawana,Sandawana, Zimbabwe.Zimbabwe. In:In: Sliwa, A.S.,A.S., Nguluwe, Nguluwe, C.A., e.A., 1984. 1984. Geological Geological setting setting of Zambian of Zam­ Gemstones,Gemstones, Rep!.Rept. ofof thethe SixthSixth AnnualAnnual CommodityCommodity Meeting,Meeting, bian emeraldemerald depositsdeposits.. Precambrian ResearchResearch,, 2525,213-28., 213-28. IMM,IMM, AIIO-AI22.A110-A122. Windley, B.F.,B.F, 1977. 1977. The The evolving evolving continents. continents. J. Wiley J. Wiley & Sons, & Sons, Giibelin,Gübelin, E.J.,E.J., 1958.1958. EmeraldsEmeralds fromfrom Sandawana.Sandawana. Journal of London.London. Gemmology, 6,6, 8,8, 340-54.340-54. TheThe ProvisionalProvisional GeologicalGeological MapMap ofof Rhodesia,Rhodesia, sixtsixthh edition,edition, Martin,Martin, H.J.,H.J., 1962.1962. SomeSome observationsobservations onon SouthernSouthern RhodesianRhodesian 1971,1971, sC'llescale 1:1:1,000,000 1,000,000.. emeraldsemeralds andand chrysobery!.chrysoberyl. ChamberChamber ofof MinesMines J.,J., SouthernSouthern Rhodesia,Rhodesia, 4,4, 10,10, 34-834-8.. Metson,Metson, N.A.,N.A., Taylor,Taylor, A.M.,A.M., 1977.1977. ObservationsObservations onon somesome RhodesianRhodesian emeraldemerald occurrences.occurrences. Journal of Gemmology, 15,15, [Manuscript[Manuscript received 19 September 1990, revised 1717 8,422-34.8, 422-34. November 1990.]1990.] J.J. Gemm.,Gemm., 1991,22,51991,22,5 273273

CrystallizedCrystallized andand massivemassive roserose quartzquartz depositsdeposits iinn BrazilBrazil Jacques P. Cassedanne, D.Sc.,* and Maurice Roditi,Roditi, FGA**FGA**

*Institute*Institute ofof Geosciences,Geosciences, UFRJ-CNPq,UFRJ-CNPq, CidadeCidade Universitaria,Universitária, IlhaIlha dodo Fundao,Fundão, 21.910,21.910, RioRio dede Janeiro,Janeiro, BrazilBrazil **Roditi**Roditi Jewellers,Jewellers, AvenidaAvenida RioRio BrancBrancoo 39,39, 15,20.090,15, 20.090, RioRio dede Janeiro,Janeiro, BrazilBrazil

AbstractAbstract ofof thisthis gemstone.gemstone. Brazilian roserose quartz quartz originates originates from from granitic granitic pegmatites pegma­ MassiveMassive oror crystallizedcrystallized BrazilianBrazilian roserose quartzquartz tites whichwhich produceproduce thethe bulkbulk ofof massivemassive roserose quartzquartz andand originatesoriginates fromfrom graniticgranitic pegmatites.pegmatites. ItsIts occurrencesoccurrences the wholewhole of of the the crystallized crystallized rose rose quartz. quartz. Other Other occurrences occurr­ maymay bbee classifiedclassified asas follows:follows: pegmatitepegmatitess wherwheree thethe ences(eluvial, (eluvial, coluvial col uvial and alluvial) and alluvial) are almost are almost insignificant. insignifi­ aforementionedaforementioned mineralmineral isis extractedextracted fromfrom thethe rocks;rocks; cant. coluviucoluviumm andand eluviumeluvium aboveabove andand inin thethe neighbour­neighbour­ TheThe massivmassivee roserose quartzquartz pegmatitepegmatitess belongbelong toto a zonedzoned hoodhood ofof thethe pegmatites,pegmatites, andand nearbynearby alluvium.alluvium. TheThe typetype characterizedcharacterized byby a blockblockyy zonezone witwithh giantgiant crystalscrystals of quartzquartz and and K-feldspar, K-feldspar, but withoutbut without sodic substitution.sodic substitu­ firstfirst typetype produceproducess thethe bulbulkk ofof massivemassive rosrosee quartz,quartz, tion.Associated Associated minerals minerals are: schorl,are: schor!, cassiterite, cassiterite, niobotantalite, niobo­ andand thethe wholewhole ofof thethe crystallizedcrystallized rosrosee quartz.quartz. tantalite, beryberyll (with(with scarcescarce palepale aquamarine),aquamarine), somesome HoweverHowever itit mustmust bbee pointedpointed outout thatthat roserose quartz­quartz- phosphatephosphate mineralsminerals and,and, locally,locally, weatheredweathered spodumene.spodumene. bearinbearingg pegmatitepegmatitess belongbelong toto twotwo typestypes whichwhich areare TheThe massivemassive rosrosee quartzquartz makemakess upup thethe wholewhole oror partpart ofof clearlclearlyy distinctdistinct oneone fromfrom thethe other:other: massivemassive roserose thethe corecore and/orand/or joinjoinss togethertogether ththee K-feldsparsK-feldspars ofof thethe quartz-bearingquartz-bearing pegmatitepegmatitess withoutwithout otherother associatedassociated blockyblocky zone.zone. TheThe depositsdeposits are:are: PePé dada Chapada,Chapada, C6rregoCórrego gemsgems (or(or somesome cleaclearr aquamarine)aquamarine) andand crystallizedcrystallized Piabanha,Piabanha, OlhoOlho d'Agua,d'Água, BoqueiraoBoqueirão anandd FazendaFazenda SaoSão rosrosee quartz-bearingquartz-bearing pegmatitespegmatites,, commoncommon produ­produ­ Jorge (State of Minas Gerais), C6rrego do Lodo, Jorge (State of Minas Gerais), Córrego do Lodo, cerscers ofof gemgem tourmalines.tourmalines. UsingUsing thethe textural­textural- Ribeirao do Largo and Fazenda Concei~ao (State of Ribeirão do Largo and Fazenda Conceição (State of parageneticparagenetic evolutionevolution schemescheme ofof VlasovVlasov (1952),(1952), Bahia),Bahia), BorrachaBorracha (State(State ofof Pernambuco)Pernambuco) anandd AltAltoo FeioFeio supplemented by the knowledge of the Brazilian (State(State ofof Paraiba).Paraíba). Geology,Geology, miningmining,, mineralogymineralogy andand supplemented by the knowledge of the Brazilian productioproductionn ofof eacheach depositdeposit isis brieflybriefly quoted.quoted. ManyMany gemgem depositsdeposits (Cassedanne,(Cassedanne, inin press),press), itit isis easyeasy toto occurrencesoccurrences ofof massivmassivee roserose quartzquartz inin pegmatitepegmatitess areare markmark thethe twotwo modelsmodels referrereferredd toto above.above. TheThe massivemassive scattered in in eastern eastern Brazil. Brazil. rosrosee quartz-bearingquartz-bearing pegmatitepegmatitess belonbelongg toto a commoncommon TheThe crystallizedcrystallized rosrosee quartzquartz pegmatitepegmatitess belonbelongg toto a andand uniquuniquee type,type, almostalmost withouwithoutt substitutionsubstitution andand ververyy differentiateddifferentiated type,type, frequentlyfrequently gemgem tourmaline­tourmaline- withwith giantgiant crystals,crystals, whereawhereass ththee crystallizedcrystallized roserose bearing with with important important Na Nasubstitution substitution bodies. bodies. Associated Asso­ quartz-bearingquartz-bearing pegmatitepegmatitess occuroccur nearnear thethe endend ofof thethe ciated minerals are: albite, muscovite, niobotantalite, minerals are: albite, muscovite, niobotantalite, pegmatiticpegmatitic evolutionevolution trend.trend. TheThe latterlatter isis Na-richNa-rich beryl andand locally locally typical typical phosphate phosphate minerals: minerals: eosphorite, eospho­ whereas the K-feldspar prevails in the first one. rite,wardite, wardite, roscherite, roscherite, etc. etc. whereas the K-feldspar prevails in the first one. The depositsdeposits of of crystallized crystallized rose rose quartz quartz are concentrated are concen­ InIn orderorder toto exemplifyexemplify thethe aboveabove basibasicc principles,principles, trated inin MinasMinas GeraisGerais State:State: JequitinhonhaJequitinhonha valleyvalley nearnear ththee mosmostt importantimportant rosrosee quartzquartz depositdeposit willwill bebe the townstowns of of Araçuaí Ara~uai and and Itinga Itinga (Lavra (Lavra da Ilha, da Ilha, Laranjeira) Laran­ described.described. OtherOther occurrencesoccurrences anandd depositsdeposits wilwilll thenthen jeira) andand RioRio DoceDoce basinbasin (Alto(Alto dada Pitora)Pitora).. SevenSeven smallsmall bebe listed.listed. TheThe lastlast sectionsection willwill dealdeal witwithh crystallizedcrystallized Occurrencesoccurrences areare alsoalso reported.reported. TheThe crystallizedcrystallized roserose roserose quartzquartz occurrences.occurrences. quartzquartz belongbelongss toto a latlatee stagestage ofof ththee pegmatitpegmatitee evolution.evolution. MassiveMassive rosrosee quartz:quartz: TheThe AltoAlto FeioFeio depositdeposit It is frequently found in vugs, perched upon quartz, It is frequently found in vugs, perched upon quartz, ItIt isis locatedlocated inin thethe StateState ofof Paraiba,Paraiba, 230230 feldsparfeldspar oror micamica,, andand occursoccurs singlesingle oror inin clusters,clusters, kilometreskilometres toto thethe nortwestnortwest ofof thethe citycity ofof Recife,Recife, nearnear rosettes,rosettes, crownscrowns oror irregularirregular groups,groups, rarelrarelyy asas sceptre.sceptre. ProminentProminent characteristicscharacteristics whicwhichh allowallow usus toto recognizerecognize a smallsmall towntown calledcalled PedraPedra Lavrada,Lavrada, andand nearnear thethe the originorigin of of many many specimens specimens are are emphasized. emphasized. boundarboundaryy betweebetweenn thethe StatesStates ofof ParaibaParaiba andand RioRio GemmologicalGemmological propertiepropertiess ooff roserose quartzquartz areare reported.reported. GrandeGrande dodo Norte.Norte. TheThe regionregion isis locatelocatedd inin a bushbush coveredcovered highighh plaiplainn andand belongsbelongs toto thethe Serid6Serido GroupGroup IntroductionIntroduction (Serid6(Serido Formation,Formation, 1,570-1,1001,570-1,100 milliomillionn yearsyears (Ma»,(Ma)), LessLess commoncommon thanthan thethe otherother varietiesvarieties ofof crystalcrystal mademade ofof biotitbiotitee garnetgarnet schistsschists whichwhich werweree intrudedintruded quartzquartz isis thethe pinpinkk colouredcoloured crystallizedcrystallized andand massivemassive bbyy severalseveral granitesgranites,, mainlymainly ofof thethe BrazilianBrazilian tectonictectonic rosrosee quartz,quartz, ofof whicwhichh BrazilBrazil isis probablyprobably,, toto date,date, thethe cyclecycle (about(about 500500 Ma).Ma). greatestgreatest producer.producer. OurOur intentionintention isis toto describedescribe TheThe depositdeposit trendstrends ENE-WSW,ENE-WSW, isis a lenticularlenticular brieflbrieflyy ththee largerlarger BrazilianBrazilian depositsdeposits andand occurrencesoccurrences pegmatitepegmatite,, outcroppingoutcropping inin a lowlow EWEW hill,hill, witwithh anan

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-12520022-1252 274274 J.J. Gemm.,Gemm., 1991,22,51991, 22, 5

MassiveMassive roserose CCrystallize ryst a II i zedd roserose quartzquartz bearingbearing quartzquartz bearingbearing pegmatpegmatiteitess pegmatitespegmatites ,J Aquamarine Gem tourmaline Aquamarine Gem tourmaline MuscoviteMuscovite bearing pegmatites bearing pegmatites Cs bearing pegmatites bearing pegmatites bearing bearing bearing pegmatites pegmatites Hh

>^'

t:/«3

~I* »"«' J PegmatitePegmatite ofof graniticgranitic textutexturere,, IVy-^l GraphicGraphic pegmatitepegmatite 1 , c::Jfc:-:::-::'v: :..-Blocky::;i Block K-feldspar,spodumeney K-f e Ids par, spodumen (olige oc(oligoclose)lase), ,c::::::J BBlock 10 c kyy andand corecore quartz,quartz, ~i°= °- "> °1 ReplacementReplacement zane,zone, ~I / <^* I CrystalsCrystals ofof rrare-elementare-elementss accessoryaccessory minerals,minerals, (]]]]][[[J MuscovMuscovite,quartite,quartzz andand albitealbite borderborder fringe,fringe , ~433 Druses.Druses .

Fig.Fig. I.1. LocationLocation ofof roserose quartz-bearingquartz-bearing pegmatitespegmatites inin a schematischematicc sectionsection ofof differentdifferent textural-paragenetictextural-paragenetic pegmatitepegmatite typestypes (Vlasov,(Vlasov, 19521952-modified) - modified).. areaarea ofof 500500 x 8080 metremetress (20,600(20,600 squaresquare metresmetres afterafter wayway ofof irregularirregular quarries,quarries, thethe olderolder onesones havinghaving Almeida,Almeida, 1946).1946). TheThe pegmatitepegmatite lieslies betweenbetween a finefine cavedcaved in.in. TheThe largerlarger excavationsexcavations inin developmentdevelopment areare grainegrainedd roserose colouredcoloured granitegranite iinn ththee southsouth andand iinn thethe weswestt andand ththee easteast ofof thethe pegmatite.pegmatite. ReservesReserves biotitbiotitee garnetgarnet schistsschists inin thethe north.north. TheThe deposit,deposit, araree notnot availableavailable butbut ververyy likelylikely amountamount toto severalseveral discovereddiscovered inin 19281928 wawass intensivelyintensively workedworked onon forfor thousandsthousands ofof tonstons (Cassedanne(Cassedanne & Cassedanne,Cassedanne, beryberyll andand tantalittantalitee duringduring WorldWorld WarWar IIII andand there­there­ 1978).1978). afterafter sporadicallysporadically quarried,quarried, forfor ththee recoveryrecovery ooff RoseRose quartz,quartz, alwaysalways xenomorphic,xenomorphic, occursoccurs asas K-feldsparK-feldspar andand rosrosee quartz.quartz. TheThe followingfollowing zoneszones irregularirregular massemassess reachingreaching uupp ttoo tentenss ofof tonstons inin succeedsucceed oneone anotheranother fromfrom thethe walwalll rocrockk toto thethe core:core: weightweight,, witwithh a variablvariablee networnetworkk ofof fissuresfissures,, eithereither - A fewfew centimetrescentimetres toto a fewfew decimetresdecimetres thickthick surroundingsurrounding giantgiant K-feldsparK-feldspar crystalscrystals oror inin severalseveral bandband ofof finefine grainedgrained mica,mica, metresmetres longlong lenseslenses inin ththee corecore ofof ththee pegmatite.pegmatite. TheThe - A centimetrecentimetre grainedgrained pegmatitepegmatite zone,zone, withwith colourcolour variesvaries fromfrom vividvivid pinpinkk toto milkymilky oror a veryvery lightlight graniticgranitic texturetexture andand largelarge prismsprisms ofof schorl,schorl, pinkish,pinkish, inin severalseveral hueshues,, bubutt neveneverr reachereachess intenseintense - A blockyblocky zonezone withwith albitealbite andand quartzquartz andand giantgiant colours.colours. TheThe roserose quartzquartz isis transparent,transparent, translucent,translucent, crystalscrystals ofof K.,feldspar,K-feldspar, somesome ofof whichwhich reachreach upup toto mistmistyy oror opalescent.opalescent. AAnn almostalmost regularregular bandinbandingg iiss 100100 tonstons inin weightweight.. TheThe areaarea coverscovers 6,8006,800 squaresquare common,common, duedue toto veryvery milkmilkyy strips,strips, a fewfew millimetresmillimetres metremetress andand massivmassivee rosrosee quartzquartz commonlycommonly sur­sur­ thickthick,, richrich inin minuteminute two-phastwo-phasee inclusions.inclusions. OnOn roundroundss thethe giantgiant crystals,crystals, exposureexposure ttoo sunsun lightlight ththee colourcolour ofof thethe rosrosee quartzquartz - A lenticularlenticular core.core. fadesfades comparativelycomparatively quickly:quickly: specimensspecimens ofof thethe MineralsMinerals associatedassociated witwithh thethe rosrosee quartz:quartz: severalseveral dumpsdumps minedmined somesome yearsyears agoago turnedturned milkmilkyy asas decimetresdecimetres long,long, milkmilkyy toto translucenttranslucent quartzquartz crys­crys­ happenehappenedd ttoo thethe frontfront ofof manmanyy houseshouses withiwithinn thethe tals,tals, morion,morion, citrine,citrine, muscovite,muscovite, lepidolite,lepidolite, berylberyl neighbourhooneighbourhoodd ofof ththee minemine,, househousess previouslypreviously (with(with somesome clearclear aquamarine),aquamarine), schorlschorl (with(with veryvery adornedadorned duringduring theitheirr erectionerection witwithh smallsmall piecespieces ofof crackedcracked blueblue andand greengreen uncommonuncommon tourmaline),tourmaline), roserose quartz.quartz. TheThe massesmasses ofof thethe latterlatter areare fracturedfractured garnet,garnet, zircon,zircon, manganesemanganese andand ironiron phospatesphospates (pre­(pre­ andand locally,locally, ironiron andand manganesemanganese oxidesoxides invadeinvade thethe dominantlydominantly heterosite),heterosite), niobotantaliteniobotantalite,, uraninite,uraninite, fissures,fissures, resultinresultingg sometimessometimes inin finefine dendriticdendritic bismutbismuthh andand bismutitbismutitee andand uncommouncommonn pyrite,pyrite, specimens.specimens. MicroscopiMicroscopicc veilveilss andand two-phastwo-phasee inclu­inclu­ chalcopyrite,chalcopyrite, chalcocitechalcocite andand covellite.covellite. MiningMining isis bbyy sionssions areare commoncommon inin ththee rosrosee quartzquartz whicwhichh exhalesexhales a JJ.. Gemm.Gemm.,, 1991,22,51991,22,5 272755

42" I

( /' + + ,r/1 il'+' I., + >'-- i ~ IO-GR4NDE 6.... -",\ ,I ·l..t.; CEARA, DO NO)TE i /J i ... \. //~. \ ,J I ,--_1 '-7. (~IOi / <.. --/" £- , r, < }----'. ....-c.. PARAIBA 8° + )/ '--.J +1 PIAUPIAUII + ... ,-/ f ~i '(( ef- ..... eI+ // J... ,/-)^ /._,rERNAMBUCO'* PERNAMBUCO ^Rtcif.cif.e ------/ l'J' fj-"--w ~ "'(":,~ r ',.....,' .8 " ...... , t ,~ \ .. ~' !, r'-) J•• !+ (t • !\ + h~ + ) , ( BAHIA + ,/ GOlASGOIAS .:' • I , f \ .... ~, .J .."_'" /' ...... -.. /r BrasiliaBrD6ilia; /*M" '-' ...... I ~,...., t ...-\.~ -is-6~f'/ + lSLl,)cay + /J ~ • + + + (\ {MINAS7 MINAS ~(. ~ N \.\.... ^/,----_/ ^ ..V" ~-.....I., ''-'''''' /--., #• ••• ., ESPIRITO ^w/* r GERAIS', •%? ESPIRITJ O T- 6ERAIS ^ ) (l) S NTO ...^/''^""V^-^-v-+-\t_----, ^ ++0 i +'L.y # SANT O I/ £*/~'IO0 Horizont***Horizont:. [7 +r------''---...J..--, # I ~ I~ OccurrencOccurrencee • j / SAO PAULO s/ __ A • !../ DeposiDepositt CO r-,,~A.---'',. ....__ SA -...O PAULO L"lr--""5m ^ RIO^' D JANEIRO )5;0 Poulo (l) r 1 PePi do6a Chopodo,Chopodo, 24°24° ,+\.+1 • 2 Corr.voCbrrogo PiobonhaPiobonho,, 3 OlhoOlho d'clVUO,d'ogua, PARANA "-;'" + PARANA 4 Boqu.irlio,Boqu«irao, 5 FFozendoundo o SaoSao Jor",Jorge, }----... _/""\./". 0 500 km 6 Corr.voCorrego dodo Lodo,Lodo, VSANTS&!J:.AA CATARINACATARINA ...------7 Ribeirao.doRibeirao,do LorIO,Largo, '_._, • 68 FoundClFaztndo Conceil:ao,Concoicao, .... + + I 9 Borrocha,Borracho, .....___ .;;:"._-'- __--''-- ______~ 1010 AltAltoo feio.foio. Fig.Fig. 2.2. MapMap showingshowing thethe locationslocations ofof massivemassive roserose quartzquartz inin Brazil.Brazil fetidfetid HzSH2S odourodour whenwhen broken.broken. ItsIts physicalphysical propro­­ north,north, mainlymainly iinn ththee "Eastern"Eastern pegmatitipegmatiticc ProvinceProvince"" pertiesperties areare classical.classical. SomeSome examplesexamples exhibitexhibit aster­aster- thatthat obliquelyobliquely crossescrosses thethe easteast ofof MinasMinas GeraisGerais andand ismism afterafter properproper cutting.cutting. entersenters intointo EspiritoEspirito SantoSanto andand southernsouthern BahiaBahia RoseRose quartzquartz fromfrom thethe AltoAlto FeioFeio isis usedused foforr States,States, asas wellwell inin thethe "Borborema"Borborema pegmatitipegmatiticc ProPro­­ ornamentalornamental purposespurposes (mainly(mainly groundground andand wallwall vince"vince" whichwhich overlapsoverlaps thethe StatesStates ofof Par:uoaParaiba andand RioRio covering)covering) andand carving,carving, sortedsorted blocksblocks ofof tenstens ooff GrandeGrande dodo Norte.Norte. TheThe roserose quartzquartz isis disseminateddisseminated kilogramskilograms beingbeing commonlycommonly extracted.extracted. TranslucentTranslucent oror inin massesmasses variablevariable inin sizesize butbut isis almostalmost alwaysalways homogeneoushomogeneous 'eyes''eyes' areare alwaysalways small. small . small,small, withwith lightlight colour.colour. ThisThis scattering scattering explains explains the the manymany quotationsquotations foundfound inin thethe literature.literature. TheThe localilocali­­ OtherOther massivemassive roserose quartzquartz depositsdeposits tiesties frequentlyfrequently reportedreported withoutwithout moremore information,information, BesidesBesides thethe deposits,deposits, hereunder hereunder described, described, where where particularlyparticularly byby FerrazFerraz (1929),(1929), LeonardosLeonardos (1936)(1936),, thethe sizesize ofof itsits concentrationconcentration allowsallows economiceconomic work­work­ CalmbachCalmbach (1938)(1938) andand MendesMendes (1973(1973 & 1975)1975) araree ing,ing, thethe massivemassive rose rose quartz quartz is is a a minor mino rconstituent constituen tof of plottedplotted onon thethe map.map. manymany BrazilianBrazilian graniticgranitic pegmatites.pegmatites. ItIt isis foundfound fromfrom InIn thethe mineralizedmineralized pegmatitespegmatites thethe roserose quartzquartz SantaSanta CatarinaCatarina inin thethe southsouth toto thethe CearaCeara inin ththee makesmakes upup thethe wholewhole oror partpart ofof thethe corecore and/orand/or joinsjoins 276 J. Gemm., 1991, 22, 5 together with K-feldspar crystals of the blocky quarrying. Blast holes are almost always manually zone. The thickness of the core, lens or string- bored, very rarely using a pneumatic drill. After shaped, varies from a few metres to more than 15; blasting, sorting takes place with the use of a its length locally reaches up to 300 metres. In the sledge-hammer for the large blocks and a light- core of the pegmatites occurs an heterogeneous hammer for the small good coloured pieces and for mixture of massive rose and milky quartz chunks translucent eyes. Output is stock-piled until it is haphazardly located and sized and sometimes transported, frequently with a short intermediate heavily fractured. Associated minerals inside the horse stage as far as the nearby road suitable for rose quartz are rare: mainly schorl in needles or in trucking. Translucent eyes are withdrawn daily scattered large prisms near the contact between the from the deposit. Morion and window quartz core and the blocky zone of the pegmatite. Un- crystals are by-products in some places. weathered, faded quartz cores remain as long walls At present the Brazilian massive rose quartz above the plains of the Borborema region. production occurs in four States: Minas Gerais, In the blocky zone, the rose quartz is also mixed Bahia, Pernambuco and Paraiba. The deposits with the milky one and welds the giant K-feldspar (plotted with a number on the map) are described crystals. It occurs generally unmixed, rarely asso­ hereunder from South to North. ciated with some druses of quartz, a little schorl and/or beryl. The mineralogy of rose quartz- Pe da Chapada bearing pegmatites is always simple: quartz, K- (= Santana, Lagoao). The Pe da Chapada deposit feldspar, sometimes albite, biotite, schorl, musco- began production in 1987 and is located 20 vite and some beryl, niobotantalite and apatite or kilometres north-west of Carai, on the right bank of spodumene, practically without collectors' speci­ the Sao Joaozinho creek. It is a N70°E running and mens. 70°NW or vertical dipping pegmatite of which the Mining in all deposits is by way of rudimentary wall rock is a fine grained grey granite. Various

P VCoraibas X 420 + L 42f10' 4 16° 20' J MINAS GERAIS

T/9 RUBELITA x V> 0 10 kn JP x + + p\ Crystallized H--16°30' -J ff x « rose quartz occurrences, Y * X Gem tourmaline Valdete occurrences. £(•*£: ITINGA ^/ X^ v^ J*lCORONEL MURTA x *Lavra da x x % +" X V llha 4*Limoe hoX Morro ^\_^ + ,*F Redondo \x>. ALoranjeira XX X v VO P j X XX X X ^ x Velha X VIRGEM DA LAPA 0 + Aracuoi / \^\^ + 4* -J -Rio 5ARACUAI X v ^Girau J

Fig. 3. Map showing the occurrences of crystallized rose quartz in Minas Gerais, Brazil. J. Gemm., 1991,22, 5 277

'''S^^Kiff001:09: :z

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• •,7i!s^;*i

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Fig. 4. Lavra do Bianor (Minas Gerais). View of the quarry with the massive rose quartz core in the foreground.

small quarries are located all along the pegmatite, rent or milky sometimes with an incipient banding. about 50 metres in length. The core is string- Also NS fissures parcel out the core, many of them shaped, 0 to 2.5 metres wide. The rose quartz is of are sealed and allow the recovery of large blocks. good medium colour with some chunks almost Sorting is manual, the darker specimens commonly pinkish-red and sub-translucent. The relative lack being small in size. Dumped fragments, more than of fissures allows the recovery of blocks several tens 50 years old, do not show any fading. Schorl, of kilograms in weight. Associated minerals are: bottle-green apatite and large weathered lathes of schorl, morion, window quartz crystals (= quartz a spodumene are associated. Production figures are fenetre or jacare) with some biotite, hematite, unknown but exceed two thousand tons (Cassedan- muscovite and scarce aquamarine. In the south a ne, 1981). thick eluvium was worked out: production ex­ ceeded 400 tons. Olho d'Agua (= Ilha Alegre, Lavra do Bianor). Located 25 Corrego Piabanha kilometres east north-east of Itaobim, on the left (= Lavra Schupp). This deposit, known more bank of the Jequitinhonha river, this N50°E run­ than 100 years ago, 14 kilometres South of Joaima, ning, vertical pegmatite with giant crystals, is 15 to produces, as regards colour, the best rose quartz in 20 metres wide and known along 60 metres in Brazil. The mine operates a NS running, sub- length. The wall rock is a fine grey granite. The rose vertical, zoned pegmatite containing a large core in quartz occurs in the core and between the feldspar the south and many giant crystals in the north. The crystals; it is massive, homogeneous or with little mining takes place within three large quarries, one banding and large translucent eyes. Recovery of which is more than 30 metres in height. The should be 60% run of mine quartz. Actual produc­ width of the pegmatite reaches 16 metres and its tion exceeds 300 tons. More than 0.8 metre long length 300 metres. K-feldspar crystals of more than schorl prisms are found in the rose quartz with a metre long are surrounded by rose quartz that also which are associated: bluish-white beryl, biotite occurs in irregular masses of several tons in weight. and some columbite. Some vugs are coated with Hues, banding and fissures vary in the deposit. The long grey to milky quartz crystals. This deposit as most common colour is bright pink, almost reddish- well as that of Pe da Chapada are currently the main pink. The quartz is translucent to almost transpa­ producers in Minas Gerais State. 278 J. Gemm., 1991,22,5

Boqueirdo (= Ze de Ionia, Cobico and Cubiculo). In the neighbourhood of Salinas, it is a N50-60°E running, highly SE dipping pegmatite which reaches 25 metres in thickness and 100 metres in length. Wall rock is a grey granite. Mining is by way of a 25 metres high quarry and several adits. In the string- shaped core, the rose quartz is highly fissured and banded and only blasted for the recovery of translu­ cent eyes. The sorted monthly production amounts to some tens of kilograms. The sorted pieces are commonly walnut to fist size. Associated minerals are: a little beryl, columbite, biotite, amethyst, hematite, schorl and quartz crystals with clay inclusions.

Fazenda Sao Jorge (= Veredinha, Boqueirao). In the south south­ west of Vitoria da Conquista, near the boundary between the Minas Gerais and Bahia States, this deposit is an EW running, 30-40°S dipping well zoned pegriiatite with a width of 8 to 10 metres, mined along a length of 120 metres. The wall rock is a highly dipping micaschist. Many irregular lenses and chunks of fetid rose quartz are scattered in the core of the pegmatite, with a parallel banding either to the dip or to the fissures that transect the core. 30% of the blasted quartz would be suitable for sale, with non-fading medium colour. Production prob­ ably exceeds 1000 tons. Irregular schorl crystals Fig. 5. Alto Feio (Paraiba). Giant K-feldspar crystal, 3 m in concentrations occur in the deposit. height, surrounded by massive rose quartz of the blocky zone.

Fig. 6. Lavra do Bianor (Minas Gerais). Large schorl crystal in Fig. 7. Alto Feio (Paraiba). Massive rose quartz, with light quartz. Length of the ball-pen: 14 cm. banding in the central quarry. Length of the ball-pen: 15 cm. J. Gemm., 1991,22, 5 279

Fig. 9. Corrego Piabanha (Minas Gerais). Sorted translucent dark pink quartz.

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Fig. 10. Alto Feio (Paraiba). Massive medium rose quartz ready for shipping. 280 J. Gemm., 1991, 22, 5

Corrego do Lodo hundred tons of massive rose quartz, as in the Pe da (= Fazenda Mangerona). 23 kilometres to the Chapada deposit. Here the rose quartz occurs as south south-west of Macarani, near the boundary blocks and little rounded boulders reaching up to 1 between Bahia and Minas Gerais States, this de­ cubic metre in volume. They generally are partly posit, found in 1957, is a NS20°E running, 60°W sunk into the soil and the regolith. Working is dipping, 8 metres wide pegmatite, known along a always easy. With the creeping action, the blocks length of 40 metres. Working was by way of a quarry run downwards, sometimes accumulating upon a 25 metres high. Rose quartz occurs in the core and flat of the hill slopes, downstream of the pegmatite surrounding giant K-feldspar crystals. Colour is (Corrego do Lodo colluvial occurrence, for inst­ medium good with a recovery of 60% from the ance), before reaching the bottom of the nearby blasted ore. Several hundreds of tons were produced creeks. A little rose quartz was produced from before temporary abandonment. Several decimetres isolated or scattered blocks sunk in gem-bearing long lathes of biotite, large twinned muscovite alluvium, worked either for chrysoberyl (Corrego flakes, schorl, window quartz crystals and some do Fogo, north of Minas Gerais State) or for beryl are associated with the rose quartz. aquamarine (Malacosta, Espirito Santo State). However, these occurrences compared with pegma­ Ribeirdo do Largo tite deposits are almost insignificant. (= Quartzo roseo). 30 kilometres south south-west of Itambe, this deposit is an N50°E running, Crystallized rose quartz deposits vertical, a few metres wide pegmatite known along a In contrast to the massive quartz deposits, the length 50 metres. Rose quartz is scattered into the deposits of crystallized rose quartz are generally string-shaped core of milky quartz, and fades after concentrated in the Minas Gerais State; the bulk some years of exposure to sunlight. A little schorl is lying in the Jequitinhonha valley near the towns of associated. Production should exceed 200 tons. Araguai and Itinga. A few others belong to the Rio Doce basin and are located south-east of Governa- Fazenda Conceiqao dor Valadares. (= Flamengo). North north-east of Jaguarari and Previously some good specimens of crystallized 13 kilometres from the Flamengo railway halt, this rose quartz were recovered during mining of the deposit is an N20°W running, 25°SW dipping, 6 to 8 Sapucaia pegmatite, near Galileia. In 1969, the metres wide pegmatite. Working is by way of a 30 x discovery of the deposit known as "Lavra da Ilha" 15 metres quarry, 10 metres in height. Rose quartz made the region of Itinga and Araguai a very famous occurs between giant K-feldspars of the blocky place worldwide due to the abundance of crystal­ zone which is surrounded by a thick granitic zone lized rose quartz. Besides this there is always easy with large graphic texture. The fetid rose quartz, access for collectors and museums in arranging with low fracturing is of good medium colour with samples of rose quartz material. Here, the speci­ white strips and grey patches. Large schorl crystals mens are preserved for mineralogical purposes or and a small amount of beryl and muscovite are used 'in natura'- in their natural state for mounting associated. Several hundreds of tons were produced in modern jewellery. before the present flooding of the quarry. The main producers, which are the deposits of Lavra da Ilha, Laranjeira and Alto da Pitora, will be Borracha described briefly hereunder and the other occurr­ (= Sitio Novo). North-west of Nazare da Mata, ences listed (see detailed map). Prominent charac­ near the boundary of the Paraiba State, this recently teristics which allow us to recognize the origin of discovered deposit, located in a small creek, is made many specimens presently found in the mineral of blocks and large boulders. These outcrop in an market will be emphasized. ellipsoidal EW area 50 x 30 metres in size, probably resulting from a pegmatite not yet unearthed by Lavra da Ilha erosion. The fetid rose quartz, with a medium good The deposit is located 40 kilometres west south­ colour shows white and grey chunks, some banded west of Itaobim on an island of the Jequitinhonha and some almost reddish-pink translucent zones. River, dry only during low-water stage, that is to say Production exceeds 150 tons. from June to October. The island, located on the right side of the river is approximately 500 metres in Before concluding it must be pointed out that length at an elevation of 250 metres. production from the deposits formed by the decom­ There is a heterogeneous pegmatite partially position of pegmatites is low to very low. The covered by unsorted alluvium, striking 40°E, dip­ eluvium that covers some pegmatites allows the ping vertically, with a wall rock of quartz micasch- local mining of from some tens and up to one ist. Workings have uncovered the pegmatite in an J. Gemm., 1991, 22, 5 281

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Fig. 8. Lavra do Bianor (Minas Gerais). Sorting massive rose quartz using a sledge-hammer.

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Fig. 11. Lavra do Ilha (Minas Gerais). The quarry, located near the end of the island flooded by the Jequitinhonha river (July 1989). 282 J. Gemm., 1991, 22, 5

irregular quarry 50 x 10 metres in extent, 15 metres other minerals. The rose quartz stands as a quite deep, which is flooded and sand-covered during regular coating upon the matrix, but more often it is every annual inundation. The pegmatite, of in radial clusters and parallel or interpenetrated medium grain size is composed essentially of aggregate crystals passing through transparent to muscovite with feldspar on both sides of the quartz rose colour. The most spectacular specimens are core, with sodic replacement bodies and small vugs those which are occurring as a crown of doubly in the vicinity of the core, where crystallized rose terminated individuals around a white or translu­ quartz is found. Associated minerals within the cent quartz crystal of decimetre size. The sizes of deposit are: pale green diamond-shaped muscovite, the individual crystals vary from a few millimetres fine groups of sphalerite crystals, niobotantalite, to two centimetres with one or two terminations. cassiterite and milky beryl. The phosphate minerals The association with clusters of eosphorite (pre­ are abundant: gem amblygonite, eosphorite, ros- dominant), roscherite, wardite and/or apatite allows cherite, rockbridgeite, montgomeryite, wardite, the quick recognition of the source of specimens whiterite, collinsite, apatite and vivianite, resulting coming from this deposit.

Fig. 12. Alto da Pitora (Minas Gerais). Small clusters of crystallized rose quartz. The sceptre is 1.5 cm long. in part from the weathering of the triphyllite, many Laranjeira Velha of them being excellent collectable specimens (Cas- (= Ademar). This deposit is located in the sedanne & Cassedanne, 1973). neighbourhood of the Lavra da Ilha. It lies in the The crystallized rose quartz belongs to a late state Laranjeira creek, a right hand tributary of the in the pegmatite evolution. Colour ranges from light Jequitinhonha river. Workings started in early 1979 purplish-pink to light pinkish-white. The crystals at the top of a small hill, where many excavations vary from translucent to quite transparent or irregularly scattered in a subcircular-shaped area opalescent and their faces are occasionally striated (approximately 600 metres in diameter) were dug in or show growth figures. Variation of shades in one search for gem tourmaline. In May of 1979, a deeper crystal is very rare. The matrix of the rose quartz pit reached the unexpected pegmatite, covered by crystals is generally milky or translucent automor- the eluvium. The pegmatite runs NW-SE with a phic or sheared quartz of the first stage. A thin film northeastern dip of 20°, a width of some metres and of chalcedony is common between the two types of an approximate extension of 100 metres. It is zoned quartz. Less frequently the matrix is composed of with large grain size. Near the core there are J. Gemm., 1991, 22, 5 283

irregular vugs that contain crystallized rose quartz, common as repeated 'sceptre' forms. A thin coating with cleavelandite, gem tourmaline and translucent of powdery white quartz sporadically covers the quartz crystals with stepped faces. Size and shape of rose quartz groups. Colours range from light pink to these vugs are variable but may reach up to one purplish-pink, reminding one of the famous sam­ metre in length. Associated minerals are: amblygo- ples from the Sapucaia mine in the same State. The nite, lepidolite, beryl, spodumene, cassiterite, crystals are transparent to translucent with, on the niobotantalite, arsenopyrite and, as phosphate whole, a relatively homogeneous coloration. minerals: frondelite, heterosite, moraesite, phos- However, light variation of shade may be observed phosiderite, cyrilovite and wardite (Cassedanne & with a lens. Cassedanne, 1980). Black or greenish-blue to water-green elbaite, The rose quartz occurs either as a partial or whole sometimes with chatoyancy, is commonly associ­ crown around the quartz crystals that may be ated with the rose quartz; but crystallized phos­ transparent or milky, sometimes fetid when broken, phate minerals never occur. This observation per­ and additionally, it may fill up the interstices mits easy distinction from the samples produced at

Fig. 14. Laranjeira (Minas Gerais). Crown of crystallized rose quartz around a grey transparent quartz crystal upon a matrix of K-feldspar and tourmaline. between the translucent quartz crystals. Crowns are the Lavra da Ilha pegmatite. the most spectacular specimens. Their axis of The other occurrences in the tourmaline-bearng symmetry may be the same as that of the supporting area are of little or no importance. They include: quartz or they may be undulating. Some specimens display a cluster of crystals lying upon a face of a Caraib'as milky quartz crystal; this may resemble the 'quartz (= Mariano Dias). Near the Rubilita town, this flowers' which occur in the amethyst region of pegmatite has produced some light coloured crys­ southern Brazil. Small crowns of crystallized rose tallized rose quartz samples, associated with green quartz around tourmaline prisms are also known to gem tourmaline. occur, being outstandingly beautiful specimens. The crowns are made of interpenetrating small Valdete prisms and rhombohedrons with their axes subpa- A few crystallized rose quartz specimens were rallel or divergent to the surface: the result is produced in this pegmatite located near Coronel dazzling. Growth figures on the crystal faces are Murta. The main specimen features remind one of 284 J. Gemm., 1991, 22, 5 those of the Laranjeira samples. Millimetric sized tite, with a wall rock of coarse granite with lens- pyrite crystals and purplish apatite are scattered shaped micaschist xenoliths. The pegmatite is 1.5 to upon the rose quartz. 5 metres wide, zoned, medium grained with a straight central blocky zone made of large K- Limoeiro feldspars, several decimetres long, spodumene Famous for its gems, years ago (Cassedanne & lathes and grey and milky quartz. Parallel fissures Lowell, 1982), this deposit produced in July 1989 with either gently NE or 20°SE dips cut the groups of crystallized rose quartz perched upon pegmatite and are frequently associated with small grey quartz crystals with a milky shell, associated elongated vugs that contain milky quartz crystals, with diamond shaped light yellow muscovite plates. hydrothermalized K-feldspar and late albite, with Some crowns around milky quartz crystals, several some muscovite, upon which rose quartz crystals centimetres in diameter, were also recovered. are perched. Other less common associated miner­ als are; schorl, late sericite and chlorite, cassiterite, Mono Redondo niobotantalite, pyrite, amblygonite, beryl and rare In the south of Barra da Salina, very good lepidolite. Iron and manganese oxides are wide­ examples of crystallized rose quartz were recovered spread and stain many specimens. Working is by in an old gem tourmaline occurrence called Morro way of twenty or so adits along the pegmatite, some Redondo. The recent reopening unearthed fine of them reaching up to 80 metres in length, with large crystallized rose quartz crowns around doubly irregular rooms and pits. Adits explore the pegma­ terminated translucent quartz crystals which reach tite about 300 metres in extension and 60 metres in up to 25 centimetres in length. height. C. Vasconcelos, from Governador Valadares, assures usi that approximately 1,000 kilograms of Laranjeira crystallized rose quartz were produced until Octo­ A rich green and blue gem tourmaline eluvium ber 1989 with 100 kilograms of superior quality and with clusters and rosettes of good crystallized rose 100 of very good colour. quartz was discovered in December 1989, 2 The rose quartz crystals occur in clusters, in kilometres north north-east of the Laranjeira Velha groups of sub-parallel prisms, isolated (single) or deposit. Below the eluvium more than 20 prospect sometimes in crowns around quartz crystals; it is adits cross the sub-horizontal, N70°E running commonly similar to that previously reported in the pegmatite. other deposits. Irregular and repeated variations of sections along the c axis are common as are growth Girau figures on the faces; small perfect sceptre specimens In the upper Piaui creek, this thin pegmatite also occur. Many samples starting as hexagonal produced in 1988 a few tens of kilograms of good prisms end with several terminations due to the well coloured, crystallized rose quartz specimens. change into parallel smaller crystals during a late The crystals, frequently doubly terminated occur as development stage. Variations of shade from trans­ crowns and rosettes perched upon or around gem parent to pink are common in the samples. Some­ tourmaline prisms of an outstanding green or blue times clusters of small sericite plates are scattered colour. Phosphate minerals are unknown here. upon the rose quartz. In the Rio Doce valley, the Sapucaia pegmatite mine is of historic interest. East south-east of The lack of phosphate minerals and tourmaline is Governador Valadares, this lens-shaped deposit 100 typical of the Pitora specimens, which are frequent­ x 40 metres in size, vertical, well zoned, was a great ly free of matrix. producer of beryl and mica during World War II. Its mineralogy is very complex having many phosphate Gemmological properties minerals. A small quantity of rosettes, crowns and In the deposits the rose quartz varies from strong chalice-shaped deep pink crystallized rose quartz rose-pink to almost white, it is always cloudy or specimens were recovered during mining activities fissured and never entirely clean, although some in the 1940 and 1950 decades. material may be found which is sufficiently clear and translucent or almost transparent to cut into Alto da Pitora faceted stones. However, the material is mainly used The crystallized rose quartz production begun in for ornamental purposes as production of figurines, the first days of 1989 in this deposit, an old gem house or ground facing, ash trays, book ends, eggs, tourmaline producer, from an extensive eluvium. spheres, cabochons, beads and small carved objects. The deposit, located 50 kilometres east south-east Material from some deposits fades after long expo­ of Governador Valadares, north-east of Galileia, on sure to light or sun. the northern slope of the Serra da Pitora range, is an Despite the fact that much of the material may be almost vertical dipping, NE-SW running pegma­ marred by cracks, the density of the rose quartz J. Gemm., 1991,22, 5 285

Fig. 13. Lavra da Ilha (Minas Gerais). Crown of crystallized rose quartz around a grey translucent quartz crystal, without matrix (sample collected in 1969). Length of the specimen: 17 cm.

Fig. 15. Rose quartz cabochon with tourmaline needles. 286286 J.J. Gemm.,Gemm., 1991,22,51991, 22, 5 doesdoes notnot varyvary veryvery muchmuch fromfrom rockrock crystalcrystal (2.65).(2.65). Internally,Internally, microscopicmicroscopic two-phasetwo-phase inclusions,inclusions, Acid,Acid, heatheat andand shockshock resistantresistant (when(when notnot heavilyheavily milkymilky veils,veils, smallsmall secondarysecondary healinghealing fracturesfractures andand fissured),fissured), thethe roserose quartzquartz crystalcrystal hashas a conchoidalconchoidal fissuresfissures withwith oror withoutwithout iridescenceiridescence areare thethe mostmost fracture.fracture. commoncommon imperfections.imperfections. TheThe refractiverefractive indicesindices areare veryvery constantconstant tootoo andand ReferencesReferences havehave thethe valuesvalues ofof 1.5441.544 forfor thethe ordinaryordinary rayray andand Almeida,Almeida, S.c.S.C. de,de, 1946.1946. TantalitaTantalita e beriloberilo emem "Alto""Alto" FeioFeio ee SerraSerra 1.5531.553 forfor thethe extraordinaryextraordinary ray.ray. TheThe signsign ofof refrac­refrac­ Branca,Branca, EstadoEstado dada Paraiba.Paraíba. AvulsoAvulso no.73,no. 73, DNPM-DFPM,DNPM-DFPM, tiontion is,is, thereforetherefore positivepositive andand thethe birefringencebirefringence isis 29pp.29 pp. 0.009.0.009. RoseRose quartzquartz showsshows a fairlyfairly strongstrong pleochro­pleochro- Calmbach,Calmbach, w.F.W.F. von,von, 1938.1938. Handbuch brasilianischer EdelsteinEdelstein ismism inin thethe deepdeep colouredcoloured materialmaterial (dark(dark pink/lightpink/light und ihrerihrer Vorkommen. Medawar,Medawar, RioRio dede Janeiro,Janeiro, 220220 pp.pp. Cassedanne,Cassedanne, J.P.,J.P., 1981.1981. LeLe quartzquartz rosrosee dudu PiabanhaPiabanha (Bresil).(Bresil). pink),pink), butbut thethe effecteffect disappearsdisappears greatlygreatly fromfrom thethe MondeetMineraux,41,18-21.Monde et Minéraux, 41, 18-21. palerpaler materialmaterial andand inin thethe veryvery palepale materialmaterial littlelittle oror Cassedanne,Cassedanne, J.P.,J.P., inin press.press. LosLos yacimientosyacimientos dede turmalinaturmalina gemagema nono dichroismdichroism cancan bebe observed.observed. RoseRose quartzquartz maymay bebe deldel Brasil.Brasil. Capricornio,Capricornio, Salta.Salta. almostalmost translucent,translucent, cloudy,cloudy, nearlynearly opaqueopaque oror almostalmost Cassedanne,Cassedanne, J.P.,J.P., Cassedanne,Cassedanne, ].0.,J.O., 1973.1973. MineralsMinerals fromfrom thethe transparent, rarely opalescent with a vitreous lustre LavraLavra dada IlhaIlha pegmatite.pegmatite. Min. Record,Record, 4,5,207-13.4, 5, 207-13. transparent, rarely opalescent with a vitreous lustre Cassedanne,Cassedanne, J.P.,J.P., Cassedanne,Cassedanne, J.O.,J.O., 1978.1978. LaLa pegmatitepegmatite Iia quartzquartz andand showsshows littlelittle fire.fire. TheThe valuevalue ofof dispersiondispersion roserose dudu AltoAlto Feio.Feio. Rev. GemmologieAFG,Gemmologie AFG, 57,11-14.57, 11-14. betweenbetween thethe BandB and G intervalinterval isis onlyonly 0.0130.013 (Webster,(Webster, Cassedanne, J.P. J.P. Cassedanne, Cassedanne, J.O., J.O., 1980. 1980. A new A new find find of crystallized of crystal­ 1970).1970). ThereThere isis nono distinctivedistinctive absorptionabsorption spectrumspectrum rose lizedquartz. rose Min. quartz. Record Min., 11, Record,6, 377-9. ll, 6, 377-9. and rose quartz shows a very little luminescence Cassedanne,Cassedanne, J.P.,J.P., Lowell,Lowell, J.,J., 1982.1982. FamousFamous mineralmineral localities:localities: and rose quartz shows a very little luminescence thethe VirgemVirgem dada LapaLapa pegmatitespegmatites.. Min. Record,Record, 13,13, I,1, 19-2819-28.. underunder ultravioletultraviolet light.light. ThereThere isis nono radioactivity.radioactivity. OnOn Ferraz,Ferraz, L.C.,L.C., 1929.1929. CompendioCompêndio dos mineraes do do Brasil Brasil emformaem forma dede heatingheating thethe pinkpink colourcolour vanishesvanishes atat aboutabout 575°C.575°C. dicciontirio.diccionário. ImpImp.. Nac.Nac.,, RiRioo dede JaneiroJaneiro,, 646455 pp.pp. MuchMuch roserose quartzquartz containscontains microscopicmicroscopic needlesneedles Leonardos,O.H.,Leonardos, O.H., 1936.1936. QuartzoQuartzo róseroseoo nnoo BrasilBrasil.. Min. & Met.,Met., 1,2,60-3. ofof rutilerutile orientedoriented inin definitedefinite crystalcrystal directionsdirections inin thethe 1, 2, 60-3. Mendes,Mendes, M.H.P.T.,M.H.P.T., 1973.1973. ComuniçãComuni~aoo sobresobre 0o projetprojetoo 'Gemas'Gemas hosthost crystal.crystal. TheseThese needlesneedles produce,produce, byby a diasterismdiasterism brasileiras'.brasileiras'. Anais XXVIII Congr. bras. Geol., AracajuAracaju,, 22,, phenomenonphenomenon a starstar effecteffect whewhenn thethe stonestone isis viewedviewed 385-94.385-94. inin thethe correctcorrect directiondirection atat a sourcesource ofof light.light. StarStar roserose Mendes,Mendes, M.H.P.T.M.H.P.T.,, 1975.1975. PosiçãiPosi~aoo dodo DepartamentDepartamentoo NacionaNacionall dada quartz is sometimes cut as round beads and spheres Produ~aoProdução Mineral Mineral com com relação rela~ao às pedras as pedras preciosas preciosas brasileiras. bra­ quartz is sometimes cut as round beads and spheres Gemologiasileiras., 21 Gemologia,, 41/42, 13-51. 21, 41142, 13-51. thatthat revealreveal a sixsix oror twelve-sidedtwelve-sided star.star. Vlasov,Vlasov, K.A.,K.A., 1952.1952. ClassificationClassification dedess pegmatitepegmatitess granitiquesgranitiques CentimetreCentimetre longlong rutilerutile oror tourmalinetourmaline needlesneedles areare d'apresd'après leurleur texturtexturee eett leuleurr paragenèseparagenese.. Bull. Acad. Sc.Sc. notnot rarerare inin massivemassive roserose quartz;quartz; thisthis materialmaterial isis usedused USSR, Ser. Geol.,Geol., no.2no.2,, 30-55.30-55. FrenchFrench translationtranslation 698698,, BRGM, Paris. forfor cuttingcutting cabochons,cabochons, beads,beads, spheresspheres andand smallsmall BRGM, Paris. Webster, R.,R., 1970. 1970. Gems. Gems. Their Their sources, sources, descriptions descriptions and and identification. identi­ figurines.figurines. IInn ththee fracturesfractures,, iroironn anandd manganesemanganese Butterworths,fication. Butterworths,London 836 pp. London 836 pp. oxideoxidess occuoccurr frequentlyfrequently asas dendrite.sdendrites anandd allowallow thethe cutcut ooff unusuaunusuall cabochons.cabochons. [[ManuscriptManuscript receivedreceived 2121 FebruaryFebruary 1990.]1990.] J.J. Gemm.,Gemm., 1991,22,51991, 22, 5 282877

SuggestionsSuggestions forfor photographingphotographing jewellerjewelleryy Giraud V. Foster and Norman].Norman J. BarkerBarker

JohnJohn HopkinsHopkins University,University, Baltimore,Baltimore, Md.,Md., USUSAA

AbstractAbstract JewelleryJewellery photographyphotography presentspresents specialspecial problemsproblems aroundaround ththee uppeupperr inneinnerr surfacsurfacee ofof a metalmetal frame.frame. withwith lighting,lighting, depthdepth ofof field,field, andand background.background. WWee TheyThey cancan bbee boughboughtt iinn a varietvarietyy ooff sizesizess andand comecome concludeconclude thatthat difficultiesdifficulties inin thesethese areasareas areare bestbest dealtdealt withwith instructionsinstructions onon hohoww ttoo correctcorrect colourcolour foforr useuse withwith byby (I)(1) choosingchoosing size,size, colour,colour, andand magnificationmagnification ooff withwith daylightdaylight film.film. UsuallUsuallyy a magentamagenta colourcolour correc­correc­ backgroundsbackgrounds thatthat areare appropriateappropriate forfor thethe purposepurpose toto tiontion filterfilter iiss needeneededd ttoo prevenpreventt anan unpleasantunpleasant whichwhich thethe photographphotograph isis toto bebe used,used, (2)(2) selectingselecting a greenishgreenish tinttint.. LightLight boxeboxess araree portableportable,, cascastt virtual­virtual­ techniquetechnique thatthat maximizesmaximizes depthdepth ofof field,field, ifif depthdepth ofof fieldfield lyly nono shadows,shadows, andand cancan bbee useusedd witwithh differentdifferent isis needed,needed, (3)(3) usingusing asas manymany lightslights asas possiblepossible toto backgrounds.backgrounds. TheiTheirr majomajorr disadvantagedisadvantage iiss thathatt theythey emphasizeemphasize reflectablereflectable colour,colour, transmittabletransmittable colour,colour, andand cancan occasionallyoccasionally producproducee unwanteunwantedd highlighthighlightss onon backgroundbackground colour,colour, (4)(4) havinghaving onon hanhandd mirrors,mirrors, magicmagic polished surfaces especially beads and rounded markers,markers, tape,tape, plasticine,plasticine, andand piecespieces ofof pseudo-suede,pseudo-suede, polished surfaces especially beads and rounded andand (5)(5) designingdesigning formatsformats thatthat areare artisticallyartistically pleasingpleasing objects.objects. HoweverHowever,, carvecarvedd piecepiecess ooff stonestone,, eveneven andand asas originaloriginal asas possible.possible. thoughthough highlhighlyy polishedpolished,, cancan usuallusuallyy bbee satisfactorilysatisfactorily photographed.photographed. ThThee methodmethod,, furthermorefurthermore,, avoidsavoids IntroductionIntroduction hothot spotsspots produceproducedd bbyy otherother techniquestechniques.. WithWith lightlight TheThe purposepurpose ofof thisthis paperpaper isis toto helphelp yoyouu toto taketake boxes,boxes, backgroundbackgroundss cancan bbee placeplacedd undeunderr themthem andand betterbetter picturespictures and,and, byby increasingincreasing youryour knowledge,knowledge, keptkept outout ooff focusfocus bbyy photographinphotographingg jewellerjewelleryy onon improveimprove thethe standardstandard ofof jewellerjewelleryy photographyphotography inin supportedsupported non-reflectinnon-reflectingg glass.glass. InIn thisthis wawayy colouredcoloured general.general. Light,Light, depthdepth ofof field,field, background,background, andand backgroundsbackgrounds dodo nonott reflecreflectt upouponn ththee jewellerjewelleryy itselfitself specialspecial effectseffects areare discussed.discussed. andand shadowsshadows araree nonott cast.cast. A thirdthird lightlight sourcesource isis electronicelectronic flash.flash. ElectronicElectronic LightLight flashflash cancan producproducee harsharshh shadowshadowss liklikee brighbrightt sun­sun­ ThereThere areare fourfour principalprincipal sourcessources ofof lightlight forfor light.light. TheseThese cancan bbee madmadee leslesss harsharshh bbyy usinusingg a softsoft photographyphotography ofof jewelleryjewellery:: sun,sun, lightlight boxes,boxes, electro­electro­ box.box. A softsoft boboxx iiss a collapsiblcollapsiblee structurstructuree whichwhich nicnic flash,flash, andand incandescentincandescent lightlight (Blaker,(Blaker, 1965a;1965a; diffusesdiffuses lighlightt andand isis designeddesigned ttoo fitfit overover a flasflashh gungun Mineo,Mineo, 1966;1966; Feininger,Feininger, 1976;1976; Grossman,Grossman, 1981).1981). head.head. ItIt iiss madmadee ooff fabricfabric,, weighweighss littlelittle,, andand comecomess inin SunlightSunlight isis excellent,excellent, butbut ifif tootoo bright,bright, willwill castcast a varietyvariety ofof sizes.sizes. SmallSmall onesones areare usefuluseful whenwhen harshharsh shadows.shadows. TheseThese cancan bbee softenedsoftened oror removedremoved workingworking inin ththee fieldfield.. IInn ththee studiostudio theythey araree unneces­unneces­ byby usingusing smallsmall mirrorsmirrors cutcut fromfrom sheetssheets ofof reflectivereflective sarysary sincesince inexpensivinexpensivee sheetssheets ooff mylamylarr cancan bbee useusedd inin plasticplastic vinyl.vinyl. WhenWhen heldheld inin placeplace byby tapetape toto objects,objects, frontfront ofof thethe lightslights oror flashflash gunsguns.. IfIf backlightinbacklightingg iiss suchsuch asas filmfilm spools,spools, thetheyy cancan directdirect additionaladditional lightlight employed,employed, ththee shadowshadowss produceproducedd inin frontfront ooff photo­photo­ wherewhere itit isis needed.needed. ByBy paintingpainting thethe surfacessurfaces ofof thethe graphedgraphed objectsobjects cacann bbee reducedreduced witwithh lighlightt reflectedreflected mirrorsmirrors withwith a blackblack magicmagic markermarker toto leaveleave onlyonly fromfrom reflectorsreflectors mademade ofof metallimetallicc cloth,cloth, foilfoil,, oorr whitewhite smallsmall unexposedunexposed areas,areas, smallsmall spotsspots ofof lightlight cancan bebe cardcard (Figure(Figure 1)1).. delivereddelivered preciselyprecisely asas desired.desired. InIn thethe fieldfield a smallsmall TheThe fourthfourth choicchoicee isis incandescenincandescentt lightinglighting,, usual­usual­ piecepiece ofof plasticineplasticine behindbehind a piecepiece ofof jewelleryjewellery cancan lyly tungstentungsten anandd oror halogenhalogen.. InIn mostmost instances,instances, elevateelevate itit above thethe backgroundbackground soso thatthat thethe back­back­ powerfulpowerful incandescentincandescent lampslamps areare unsatisfactorunsatisfactoryy forfor groundground wilwilll bbee outout ofof focus. A wordword ofof caution:caution: sincesince photographingphotographing jewellerjewelleryy especiallespeciallyy jewellerjewelleryy thatthat colourcolour valuesvalues areare atat theirtheir bestbest atat mid-daymid-day andand shiftshift toto hashas specularspecular reflectionsreflections,, bbee thetheyy frofromm metametall oror redred andand blueblue valuesvalues inin thethe earlyearly morningmorning andand latelate gemstones.gemstones. TheTheyy shoulshouldd nonott bbee useusedd closeclose ttoo thethe eveningevening respectively,respectively, picturespictures shouldshould bebe takentaken atat subject,subject, sincsincee thetheyy tentendd toto producproducee a flaflatt appear­appear­ mid-daymid-day ifif possible.possible. ance.ance. LightingLighting iiss bettebetterr controllecontrolledd witwithh multiplemultiple TheThe secondsecond choicechoice ofof lightlight isis a lightlight box.box. LightLight smallsmall sourcessources sucsuchh asas fibre-opticfibre-optic wandswands.. ThThee latterlatter boxesboxes useuse a circularcircular oror rectangularrectangular fluorescentfluorescent tubetube cancan bbee positionepositionedd toto direcdirectt lightlight iinn almostalmost anyany

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSNISSN:: 0022-1250022-12522 288288 J.J. Gemm.Gemm.,, 1991,22,51991,22,5

REFLEC~REFLECTORS ______~ o BACKGROUNDBACKGROUND I FLASHFLASH OBJECT } OBJECT) HEADSHEADS CAMERACAMERoA

1f () ! I MYLARMYLAR SCREESCREENN

Fig.Fig. 1.1. BacklightingBacklighting providesprovides a backgroundbackground ofof variedvaried intensityintensity andand highlightshighlights thathatt areare oonn ththee uppeupperr ririmm ofof ththee subjecsubjectt andand nonott onon thethe surfacessurfaces ofof interest.interest. ToTo softensoften frontalfrontal shadows,shadows, lightlight shouldshould bebe diffuseddiffused atat ththee sourcsourcee anandd thethenn reflectereflectedd ontoonto ththee subjectsubject beingbeing photographed.photographed.

CAMERACAMERA

NON-REFLECNON-REFLECTIV TIVEE Ir fJ GLASSGLASS PPLATLATE E L -- I \ SUPPORSUpp ORTT LEGSLEGS ,,~

BACKGROUNDBACKGROUND

Fig.Fig. 2.2. TheThe flatflat appearanceappearance producedproduced bbyy directdirect lightinglighting fromfrom a singlesingle sourcesource cancan bbee improvedimproved bbyy usinusingg fibre-optifibre·opticc wandswands.. BByy mountingmounting jewelleryjewellery onon non·non-reflectin reflectingg glassglass aboveabove thethe backgroundbackground,, multiplemultiple wandwandss (indicate(indicatedd bbyy arrows)arrows) cancan bebe directeddirected toto produceproduce spotlightspotlight backgrounds,backgrounds, highhigh lightslights andand fullfull lightslights onon thethe subjectsubject itself,itself, anandd transmittetransmittedd lighlightt throughthrough gemstonesgemstones iiff theythey areare notnot backed.backed. J. Gemm., 1991, 22, 5 289

direction. Furthermore, the light can be diffused tion. This can be done in three ways. First, one can and intensity varied as needed. Figure 2 illustrates use a small aperture (Lefkowitz, 1979; Blaker, how a piece of jewellery might be photographed. 1989b). The two factors that determine depth of The object is placed on a supported plate of field are magnification and aperture opening. The non-reflecting glass. The arrows indicate how two smaller the aperture the greater the depth of field fibre-optic wands can be directed to produce a light and the improvement in focus. Second, one can use on the background, two to illuminate the subject either a view or field camera both of which allow from above, and two to illuminate the subject from tilting of the lens board and film plane, thereby below if the jewellery has unbacked transparent extending depth of focus (Shaman, 1977; Stroebel, stones. One need not stop at six lights. In some 1986). These large format cameras are relatively instances more may be better. The lights on the heavy, usually take considerable time to set up and, background produce either a spotlight or a vignet­ as a consequence, restrict the number of photo­ ted effect depending on their intensity. If there are graphs that can be taken in a day. They do, however, transparent coloured stones in open backed set­ produce negatives that are large enough to be tings, small snoots or fibre-optic needles, which can retouched. The third choice is scanning light photo- direct light in a fine beam, can be used to illuminate macrography (McLachlan, 1964; Schram, 1981; them from behind to bring out colour. The major Root, 1985; Gerakaris, 1986). See Figure 3. This advantage of incandescent artificial lighting is that technique uses multiple light sources to produce a one can see the results of one's lighting and make plane of light that is less than the depth of field of whatever adjustments are necessary. the camera's lens. The lens of the camera is opened in a dark room while the object is mechanically Depth of field raised through the plane of light. The camera is When photographing flat jewellery such as neck­ focused in this plane of light so that, as the object laces, depth of field is rarely a problem. However, it passes through it, it is painted by the light and the is often necessary to maximize depth of field, when entire image is recorded in focus. Unfortunately taking pictures of jewellery that is bulky for its size, scanning light photomacrography systems are ex­ like bracelets or small objects under high magnifica­ pensive and are not without their detractions. They

Fig. 3. Scanning light photomacrographs are produced by photographing the object in a dark environment as it is mechanically moved through a plane of light less than the depth of field of the lens. By focusing on the object in the plane of light, the entire image recorded appears in focus. Magnification is limited only by the width of the plane of light and vibration. 290 J. Gemm., 1991,22,5

are cumbersome to carry. When photographing sand papers, feathers, flower petals, silks, velvets - faceted stones, specular reflections can be very even human and non-human models - the list is troublesome. Finally, exposures must be approxi­ endless. Backgrounds can also be made by projec­ mated so that the method is wasteful of film. tion to introduce colours, abstract patterns, tex­ tures, and scenery. Background We tender five suggestions to optimize back­ Special effects ground (Blaker, 1965b; Blaker, 1989a). First, select Spectacular pictures are great challenges to take a background that is appropriate for the use to and reputations of photographers are made on which the picture is going to be put. Second, if these. The following are a few suggestions on how coarse textures are to be used, photograph them at to achieve special effects but, with a little imagina­ least partially out of focus. Third, be inventive with tion, others can be developed. colour and light. Fourth, be sure, if jewellery is If one wishes to photograph a group of stones at being photographed under magnification, that no right angles to their tables, this can be done with a dust is present. Fifth, do not be afraid to try unusual black background by mounting the stones upright backgrounds. Each of these points deserves brief on a black matte acrylic surface with black plasti­ discussion. cine or, if another background colour is required, by The background should be aesthetically chosen gluing them to a piece of non-reflecting transparent and relate well in size to the object being photo­ glass raised above a background colour as needed graphed. Colour is important as well. There are no and photographing straight on. If one uses large rules about colour. Most people find, however, that format film, one can then retouch the negatives with greys, blacks, and neutral blues are more satisfac­ emulsion paint. One can also mount the stones with tory than bright yellows, greens, and purples. If you their tables on the glass and photograph them with have a need for bright colours, consider using silks the camera beneath them facing upwards. and rayons that have colours with more colour To photograph a piece of jewellery on an exotic saturation than dyed materials like paper and setting like clouds, ocean waves, or desert, put the cotton. object on a mirror and mount the background Cloth fabrics used for background have texture. picture on a card parallel to and above the mirror. These are often disconcerting if in focus. A small Then photograph the jewellery with the back­ piece of black plasticine can be shaped to raise a ground reflected on the mirror. piece of jewellery sufficiently that texture is poorly One of the biggest problems in taking pictures of perceived by the camera. If there is concern that the gemstones is photographing emeralds. Irrespective plasticine is going to leave an oily mark on the of their original colour, the colour reproduced is background, it can be placed on a coin. For work in frequently murky. Films do not exist that consis­ the field, a piece of black or maroon pseudo-suede, tently record a good emerald green. Sometimes it is as well as mirrors, magic markers, tape, and plasti­ necessary to retouch a poor green with Kodak cine, are useful to have available. Pseudo-suede can emulsion paint to get a satisfactory colour. be brushed free of dust and washed when dirty. Finally, how can one photograph a long thin Another reason for not placing jewellery with metal bracelet? True, one can photograph it diagonally or surfaces directly on coloured fabrics is that the perhaps partially curled upon itself, but a more metal will often take on the colour of the back­ attractive alternative method exists. Using a black ground. A small piece of non-reflecting glass that reflecting acrylic surface and standing the bracelet can be supported by film spools is a useful addition on its side, one can often obtain a striking image of to the camera bag. the bracelet and its reflection. Polished metals or Taking pictures of jewellery at high magnification mirrors can also be used as reflecting surfaces. introduces the problem of dust. Canned air with a fine tubular nozzle is a convenient way to blow away Summary dust, but should not be carried on airplanes, since In conclusion we would like to emphasize five pressure changes can cause explosions. Small points. First, select backgrounds of size, colour, and brushes work well on glass and if one uses velvet, magnification appropriate to the purpose for which pseudo-suede, or other fabric backgrounds, sticky the photograph is to be used. Second, choose a tape of any sort can be very helpful. technique that maximizes depth of focus, if depth of Be creative about backgrounds. Most hobby field is needed. Third, use as many lights as shops sell plastic acrylics that look like marble, necessary to optimize reflective colour, transmitted granite, slate, sandstone, etc. that make excellent as colour, and background colour. Fourth, to be always well as inexpensive backgrounds. Also available are prepared to take pictures of jewellery, have available wood veneers, coloured woods, slates, sands, and pieces of pseudo-suede, mirrors, magic markers, J.J. Gernrn.,Gemm., 1991,22,51991,22,5 291291

tape,tape, andand plasticine.plasticine. Fifth,Fifth, andand byby nono meansmeans leastleast Grossman,Grossman, J.,J., 1981.1981. LargLargee ProducProductt LightingLighting foforr SmallSmall ProductProduct important,important, designdesign formatsformats thatthat areare artisticallyartistically pleas­pleas­ Photography,Photography, Industrial PhotographyPhotography,, 3030,, 27-927-9.. inging andand asas originaloriginal asas youyou cancan makemake them.them. Lefkowitz,Lefkowitz, L.,L., 1979.1979. LightinLightingg anandd ReflectioReflectionn ControlControl,, ChapterChapter 8,8, Manual of Closeup PhotographyPhotography,, AmphotAmphotoo Publication,Publication, NewNew YorkYork,, 177-99.177-99. ReferencesReferences McLachlan,McLachlan, D.D. Jr.Jr.,, 1964.1964. ExtremExtremee FocalFocal DeptDepthh inin Microscopy.Microscopy. Blaker,Blaker, A.A.,A.A., 1965a.1965a. Lighting,Lighting, ChapterChapter 4,4, Photography forfor Applied Optics,Optics, 3,3, 9,1009-)3.9, 1009-13. Scientific Publication,Publication, WHoW.H. FreemanFreeman andand Company,Company, SanSan Mineo, J.,J., 1966. 1966. Reflection Reflection Control Control in Small in Small Object Object Photography, Photogra­ Francisco,Francisco, California,California, 17-26.17-26. Industrialphy, Industrial Photography Photography,, 30, 27-9. 30, 27-9. Blaker,Blaker, A.A.,A.A., 1965b.1965b. Backgrounds,Backgrounds, ChapterChapter 5,5, Photography forfor Root,Root, N.,N., 1985.1985. LighLightt ScanningScanning PhotomacrographPhotomacrographyy - A BriefBrief Scientific Publication,Publication, WHoW.H. FreemanFreeman andand Company,Company, SanSan History and and Its Its Current Current Status. Status. Journal Journal of Biological of Biological Photography Photo­ , Francisco,Francisco, California,California, 26-36.26-36. 53, 69-77.graphy, 53, 69-77. Blaker,Blaker, A.A.,A.A., 1989a.1989a. Backgrounds,Backgrounds, ChapterChapter 3,3, Handbook forfor Schram,Schram, R.R.R.R.,, 1981.1981. LighLightt ScanningScanning PhotographyPhotography.. Microscope, Scientific Photography,Photography, WHoW.H. FreemanFreeman andand Company,Company, SanSan 29,29, )3-7.13-7. Francisco,Francisco, California,California, 80-90.80-90. Shaman,Shaman, H.H.,, 1977.1977. The View Camera: Operations and TechniquesTechniques,, Blaker,Blaker, A.A.,A.A., 1989b.1989b. SmallSmall ObjectObject Photography,Photography, ChapterChapter 6,6, Amphoto,Amphoto, GardenGarden CityCity,, N.Y.N. Y.,, 25-4025-40.. Handbook for Scientific Photography, WHoW.H. FreemanFreeman andand Stroebel,Stroebel, L.L.,, 1986.1986. DeptDepthh ooff Field.Field. ChapteChapterr 8.8. View Camera Company,Company, SanSan Francisco,Francisco, California.California. Technique. 5t5thh Edition.Edition. FocaFocall PressPress,, BostonBoston,, 123-34.123-34. Feininger, A., A., 1976. 1976. Light Light and andLighting Lighting in Photography in Photography,, Amphoto Am­ photo Press,ress, GardenGarden City,City, NewNew York,York, 126-52.126-52. [M[Manuscrip anuscriptt received 4 September 1990.J1990.] Gerakaris, J.G., J.G., 1986. 1986. A SecondA Second Look Lookat a Scanning at a Scanning Light Light Photomacrography.Photomacrography. Microscope,Microscope, 34,34, 1-8.1-8.

PORTABLEPORTABLE POLARISCOPEPOLARISCOPE

FromFrom thethe GemmologicalGemmological InstrumentsInstruments LtdLtd rangerange ofof equipment.equipment. TheThe RaynerRayner battery-operatedbattery-operated portableportable polariscope;polariscope; basedbased onon thethe principleprinciple ofof a Scopelight.Scopelight. SimplySimply insertinsert a gemstonegemstone intointo thethe polariscopepolariscope 'well:'well', rotaterotate thethe filter, andand view view with with ease ease whetherwhether thethe gemstonegemstone isis singlysingly oror doublydoubly refractive.refractive. QuickQuick andand effortlesseffortless distinctiondistinction betweenbetween manymany gemgem species.species.

IdeallyIdeally suitedsuited toto thethe gemmologistgemmologist andand jewellejewellerr alikealike andand attractivelyattractively pricedpriced atat £54.00£54.00 plusplus VAT,VAT, postagepostage andand packing.packing.

GEMMOLOGICALGEMMOLOGICAL INSTRUMENTSINSTRUMENTS LTLTDD A divisiondivision ofof TheThe GemmologicalGemmological AssociationAssociation andand GemGem TestingTesting LaboratoryLaboratory ofof GreaGreatt BritainBritain

2727 GrevilleGreville Street,Street, LondonLondon ECINEClN 8SU.8SU. Telephone:Telephone: 071-404071-404 33343334 Fax:Fax: 071-40071-4044 88438843 292922 JJ.. Gemm.Gernrn.,, 19911991,22,5, 22, 5

VulcanitVulcanitee oorr gutta-percha?gutta-percha? ThatThat isis thethe questionquestion Grahame BrownBrown BrisbaneBrisbane,, Australia

Fig.Fig. I.1. MouldedMoulded gutta-perchagutta-percha'hand'brooc 'hand' broochh ofof sisimilamilarr designdesign toto thatthat ofof thethe vulcanitvulcanitee broocbroochh illustratedillustrated asas FigurFiguree 7.107.10 inin HelenHelen Muller'sMuller's book Jet.Jet.

AbstractAbstract (Figure(Figure 2) areare twtwoo look-alikelook-alike imitationsimitations thathatt maymay BothBoth mouldedmoulded gutta-percha,gutta-percha, andand vulcanite,vulcanite, havehave beenbeen confuseconfuse gemmologistsgemmologists whenwhen theythey attemptattempt toto iden­iden­ usedused toto imitateimitate jetjet jewelleryjewellery ofof VictorianVictorian age.age. DueDue toto tifytify articlesarticles ofof VictorianVictorian jewelleryjewellery purportedpurported toto bebe gutta-percha's softness,softness, andand itsits lowlow moulding moulding tempera­ temperature,manufacturedmanufacture d fromfrom jetjet.. IndeedIndeed thethe jejett expert,expert, HelenHelen 1 ture, thisthis naturalnatural rubberrubber isis lessless likelylikely toto bebe foundfound todaytoday Muller 1,, hahass statedstated thatthat gutta-perchagutta-percha (sic[sic] 1 isis 'a'a thanthan jetjet imitationsimitations thatthat havehave beenbeen mouldedmoulded underunder heatheat naturalnatural plasticplastic obtainedobtained fromfrom thethe milkymilky secretionsecretion ofof andand prepressurssuree fromfrom man-mademan-made thermothermosettinsettingg vulcanite. a treetree DichopsisDichopsisgutta'.gutta' thatthat waswas ''...... notnot durabledurable andand itit The resultsresults ofof this this investigation investigation suggest suggest that that guttapercha gutta­ isis mostmost likelylikely thatthat thosethose piecespieces ofof jewelleryjewellery de­de­ percha jewelleryjewellery cancan bebe effectiveleffectivelyy didistinguishestinguishedd fromfrom scribedscribed asas gutta-perchagutta-percha areare inin factfact mademade ofof vuJca­vulca­ vulcanitevulcanite jewelleryjewellery byby a combinationcombination ofof carefulcareful handhand lens examination,examination, judiciouslyjudiciously appliedapplied hothot pointpoint tests,tests, nite~nite'. and differentialdifferential solubilitysolubility tests. tests. AsAs mymy experienceexperience withwith allegedalleged gutta-perchagutta-percha oror vuJcanitevulcanite jewelleryjewellery doesdoes notnot supportsupport HelenHelen Muller'sMuller's IntroductionIntroduction unequivocalunequivocal statement;statement; and,and, asas thethe gemmologicalgemmological MouldedMoulded vuJcanitevulcanite (Figure(Figure I1)) andand gutta-perchagutta-percha literatureliterature isis remarkablyremarkably vaguevague aboutabout thethe identifyingidentifying

© CopyrightCopyright thethe GemmologicalGemmological AAssociatiossociationn ISSN: 0022-12520022-1252 J. Gemm., 1991,22, 5 293

features of both jewellery grade gutta-percha and vulcanite; perhaps the time is appropriate when the sources, methods of manufacture, chemistry and gemmological properties of both these materials should be described.

What is gutta-percha? Gutta-percha2,3 is a soft, heat sensitive, inelastic greyish to brownish solid substance obtained by evaporating the milky latex of two species of Malaysian tree - the no longer cultivated Palaquium gutta*, and the commercially cultivated P. oblongi- folia.

Source Before Western explorers discovered the Malay­ sian Peninsular, its Malay and Chinese inhabitants used gutta-percha to manufacture large, light, fib­ rous textured drinking bowls that they called mazers. Early European explorers mis-identified the wood-like texture of these bowls, so their journals recorded that the mazers they acquired had been manufactured from 'mazer wood'. This misunder­ standing was the historical source of the oft-quoted 'mazer wood tree' origin for gutta-percha. For over 200 years, from the early 17th century, 'mazer wood' was brought into Europe as a curios­ ity. However, by the early 1840s 'maser wood' had been correctly identified as being an evaporated plant sap product. It was subsequently named gutta-percha. In 1848, gutta-percha was first used Fig. 2. Simple moulded vulcanite pendant. commercially to sheathe the newly introduced underwater telegraph cables of Ernst Werner von chains of isoprene mer (polymer) units. Gutta­ Siemens. Interestingly, late in the 19th century, percha has a molecular weight of about 30,000. gutta-percha was replaced for this purpose by the much more durable and recently discovered insulat­ CH ing material - vulcanite. By the 1850s Europe was a CH,— infatuated by gutta-percha, and all manner of \ / utilitarian and decorative objects were moulded c = c from it - including the gutta-percha golf balls, or 'gutties', used by golfers from the late 19th century — CH, H until the 1920s. The source for gutta-percha, latex, is usually Isoprene polymer collected from deliberately felled trees, since gutta­ percha latex only flows very slowly from tapping Individual polyisoprene chains, forming gutta­ incisions cut through the bark of standing trees. At percha, are held together by weak fields of attraction harvest, mature trees yield sufficient Palaquium known as Van der Waals forces. In nature, gutta­ latex to furnish 1-2 kg of gutta-percha. When this percha predominantly occurs as crystalline alpha milky suspension is boiled over open wood fires it gutta-percha - a linear trans-polyisoprene form, yields a solidified mass of gutta-percha. having its chain forming CH2 units located on opposite sides of the double bond. This linear Chemistry structure gives gutta-percha some mechanical Gutta-percha is a naturally occurring polymer of strength and reduced plasticity. isoprene, formed from covalently linked linear When naturally occurring crystalline alpha gutta­ percha is heated above 65°C it melts. Extremely *Palaquium gutta is the current name for the tree slow cooling of this melt will allow alpha gutta­ Dichopsis gutta, quoted by H. Muller. percha to recrystallize. But, more rapid cooling, 294294 JJ.. Gemm.Gemm.,, 1991,22,51991,22, 5

-CH- CH,, H CH,l CHCH,, - —CHCH l, H \~ / \~ / ~\ / C=CC =C C=CC =C C=CC == C / \~ / \~ / / \~ CH, CH,—CHCH - CH, H CHCH, CH, - l 2 l l CH, - J Trans-polyisoprene (Alpha (Alpha gutta-percha) gutta-percha) suchsuch as·as thethe raterate ofof coolingcooling thatthat occursoccurs whenwhen ThermalThermal stability:stability: SoftensSoftens andand becomebecomess pliablepliable gutta-perchagutta-percha latexlatex isis evaporatedevaporated toto yieldyield solidsolid betweebetweenn 40-50°C.40-50°C MeltsMelts betweenbetween 65°65° andand 70°C.70°C AnAn gutta-percha,gutta-percha, willwill yielyieldd crystallinecrystalline betbetaa gutta­gutta­ appliedapplied hothot pointpoint wilwilll yielyieldd a distinctivedistinctive odourodour thatthat perchperchaa havinhavingg a distinctivedistinctive diagonaldiagonal linearlinear struc­struc­ doesdoes notnot resemblresemblee thatthat ofof burninburningg rubber.rubber. ture.ture. TheThe greyishgreyish oror brownishbrownish fibrousfibrous ttoo granulargranular Jewellery grade gutta-perchagutta-percha surfacesurface ofof mouldedmoulded gutta-perchagutta-percha jewellerjewelleryy isis invari­invari­ WhenWhen gutta-perchagutta-percha isis formulated,formulated, forfor thermo­thermo­ ablyably paintepaintedd blackblack oror darkdark brownbrown,, toto simulatesimulate thethe plasticplastic mouldingmoulding purpospurposee (e.g.(e.g. toto createcreate imitationsimitations smooth,smooth, highlyhighly lustrous,lustrous, blacblackk polishepolishedd surfacesurface ofof jet)jet),, gutta-perchagutta-percha mustmust bbee remelteremeltedd andand filledfilled attainedattained bbyy jetjet.. witwithh inertinert materialsmaterials suchsuch asas zinczinc oxideoxide and/orand/or chalk,chalk, WithWith increasingincreasing age,age, oxidationoxidation causescauses jewelleryjewellery andand variousvarious waxewaxess andand resins.resins. SubsequentSubsequent heatheat gradegrade gutta-perchagutta-percha ttoo becombecomee brittlebrittle,, whilwhilee itsits softening,softening, andand mouldingmoulding,, ofof thisthis filledfilled gutta-perchagutta-percha surfacesurface tendt~ndss toto becombecomee crazedcrazed bbyy a reticulatedreticulated will,will, oonn coolingcooling,, yielyieldd a mixturmixturee ofof abouaboutt 60%60% betabeta patternpattern ooff superficialsuperficial crackscracks.. Additionally,Additionally, witwithh ageage gutta-perchagutta-percha andand 40%40% amorphousamorphous gutta-percha.gutta-percha. paintepaintedd gutta-perchagutta-percha surfacessurfaces tendtend toto loselose muchmuch ooff ThisThis jewellerjewelleryy gradegrade gutta-perchgutta-perchaa hashas thethe followingfollowing theirtheir coating.coating. gemmologicalgemmological characteristics:characteristics: WhatWhat iiss vulcanite?vulcanite? 4 5 Colour:Colour: Reddis.hReddish toto brownishbrownish greygrey Vulcanite ,5' isis a man-mademan-made thermosetthermoset solidsolid SurfaceSurface texturetexture:: FibrousFibrous ttoo coarselycoarsely granulargranular manufacturedmanufactured byby compoundingcompounding naturalnatural rubberrubber oror Hardness:Hardness: 1 (easily(easily scratchedscratched byby thethe fingerfinger nail)nail) caoutchouc with with up up toto 32% 32% sulphur sulphur at a t 168°C168°C and and 90 90 66 2 Tenacity:Tenacity: BrittleBrittle -psIpsi (0.62(0.62 x 10 N/m )) ofof steamsteam pressurepressure.. TheThe Sectility;Sectility: ReadilReadilyy paredpared witwithh a sharpsharp bladeblade processprocess ofof vulcanizatiovulcanizationn wawass discovereddiscovered inin ththee latelate SpecificSpecific gravity;gravity: 0.96-1.00.96-1.0 (pure(pure gutta-percha)gutta-percha) 1830s,1830s, witwithh ththee vulcanizatiovulcanizationn processprocess beingbeing 1.2-1. 9 (filled(filled gutta-percha)gutta-percha) patentedpatented bbyy ththee AmericanAmerican CharleCharless GoodyeaGoodyearr inin 'Spot''Spot' refractivrefractivee index:index: SRSR 1.581.58 (difficult(difficult toto deter­deter­ 1842.1842. minemine duedue toto .thethe solubilitysolubility ofof gutta-perchgutta-perchaa inin refractometerefractometerr fluid)fluid) Source Lustre:Lustre: waxywaxy Caoutchouc, thethe naturanaturall rubberrubber ofof CentralCentral andand Diaphaneity:Diaphaneity: OpaqueOpaque SouthSouth AmericanAmerican Indians,Indians, isis produceproducedd fromfrom thethe Solubility;Solubility: InsolubleInsoluble inin water.water. ReadilyReadily solublesoluble inin commoncommon organicorganic solventssolvents e.g.e.g. toluenetoluene** (toluo!),(toluol), chloroform,chloroform, etherether *CAUTION:*CAUTION: Hepatotoxic,Hepatotoxic, carcinogenic.carcinogenic.

-CH,•CH, H \~ / cC=C —c / \~ CH,l CHCH,—CH,- CH,, H "C=C / / ~\ . CH,2 /-Li CH, CH -CHl H \ / C=C "c = c / / ~ CH CH _ CH,l/ \ CH,2 Trans-polyisoprene (Beta (Beta gutta-percha) gutta-percha) J.J. Gemm.,Gemm., 1991,22,51991,22,5 292955

1 CH, H I

\ / rH CH, CH, C = C CH> CH,- / C=C CH3 \H/ \ \

/ ' \ / \ - CH, H CH, H L . •...—., Cis-polyisoprene (Natural (Natural rubber) rubber) drieddried milkymilky latexlatex ofof severalseveral tropicaltropical treestrees including:including: polymerpolymer unitsunits covalentlycovalently linkelinkedd iinn a kinkedkinked 'cis''cis' thethe Sephonia elasticaelastica of of Brazil, Brazil ,the the Castilloa Castilloa elastica elastica formform (linking(linking CH2z groupsgroups oonn ththee samesame sidsidee ofof thethe ofof CentalCental America,America, thethe Ficus elastica ofof south-eastsouth-east doubledouble bond).bond). Asia,Asia, andand thethe Urceola elastica ofof thethe islandisland ofof ItIt isis thithiss kinkekinkedd chain-likchain-likee structurestructure thatthat givesgives Borneo.Borneo. TheThe latex,latex, fromfrom whichwhich naturanaturall rubberrubber isis naturanaturall rubberubberr ititss elasticityelasticity.. Structurally,Structurally, naturalnatural derived,derived, isis primarilprimarilyy anan aqueousaqueous suspensionsuspension ofof rubberrubber andand gutta-perchgutta-perchaa areare botbothh isopreneisoprene isomers.isomers. microscopicmicroscopic particlesparticles ofof caoutchouc. Natural Natura lrubber rubbe r However,However, itit was soosoonn discoveredIscoveredd thatthat naturalnatural latexlatex hashas a specificspecific gravitygravity whicwhichh maymay varyvary fromfrom rubberrubber becambecamee harhardd anandd brittlbrittlee iinn coldcold weather,weather, yetyet 1.021.02 toto 1.41,1.41, dependingdepending onon itsits caoutchouc content. content . waswas stickysticky inin hohott weather.weather. ExperimentExperimentss ttoo increaseincrease RecoveryRecovery ofof naturalnatural rubberrubber fromfrom latexlatex involvesinvolves thethe usefulnessusefulness ofof naturanaturall rubberrubber,, ledled ttoo ththee discov­discov­ thethe followingfollowing steps:steps: eryery thatthat bbyy chemicallychemically reactinreactingg naturalnatural rubberubberr withwith 1.1. SolidificationSolidification ofof rubberrubber fromfrom thethe latex:latex: byby sulphur,sulphur, untiluntil alalll thethe doubldoublee bondbondss ooff naturanaturall rubberrubber evaporationevaporation inin sunlightsunlight oror artificial heat;heat; oror byby werewere saturated,saturated, stablestable man-madman-madee harhardd rubberubberr oror aceticacetic oror citriccitric acidacid precipitation.precipitation. EvaporatedEvaporated vulcanitevulcanite wawass formed.formed. 'biscuit''biscuit' isis creamycreamy white,white, odourless,odourless, andand hashas a specificspecific gravitygravity ofof 0.915.0.915. Jewellery grade vulcanitevulcanite 2.2. SolidSolid impuritiesimpurities areare removedremoved fromfrom thethe 'biscuit''biscuit' ThermosettingThermosetting blacblackk jewellerjewelleryy gradegrade vulcanite,vulcanite, byby shreddingshredding andand protractedprotracted washingwashing withwith water.water. oror 'ebonite~'ebonite', was soosoonn formulatedformulated foforr ususee iinn thethe 3.3. CleanedCleaned 'biscuit''biscuit' isis consolidatedconsolidated andand compressedcompressed creationcreation ooff relativelrelativelyy inexpensiveinexpensive mouldemouldedd imita­imita­ inin steamsteam heatedheated traystrays intointo thickthick sheetssheets ofof naturalnatural tionstions ofof ththee thethenn populapopularr jetjet.. 'Ebonite''Ebonite' was formu­formu­ rubber.rubber. latedlated toto containcontain 50%50% naturanaturall rubberrubber,, 30%30% sulphur,sulphur, SimpleSimple globalglobal economicseconomics soonsoon dictateddictated thatthat 3%3% blackblack pigmentpigment,, anandd 17%17% fillersftllers.. JewellerJewelleryy gradegrade naturallynaturally gatheredgathered BrazilianBrazilian ParaPara rubberrubber waswas soonsoon 'ebonite''ebonite' vulcanitvulcanitee hahass ththee followinfollowingg gemmologicalgemmological replacedreplaced byby cultivatedcultivated plantationplantation rubberrubber fromfrom characteristics:characteristics: south-eastsouth-east Asia.Asia. InIn EuropeEurope andand America,America, caoutchouc becamebecame knownknown asas India rubber; asas a a consequence consequence ofof Colour:Colour: BlackBlack,, bubutt witwithh timetime oxidatiooxidationn modifiemodifiess thethe itsits initialinitial majormajor useuse asas anan efficientefficient erasereraser ofof blackblack vulcanitevulcanite huhuee ttoo brownbrown,, khakikhaki,, thethenn yellowishyellowish pencilpencil marksmarks fromfrom paper.paper. brownbrown SurfaceSurface texture:texture: CompactCompact Chemistry Hardness:Hardness: 1-21-2 (No(Nott scratchescratchedd bbyy fingefingerr nailnail,, butbut Structurally,Structurally, naturalnatural rubberrubber isis alsoalso anan isopreneisoprene jusjustt scratchedscratched bbyy gypsum)gypsum) polymerpolymer (polyisoprene)(polyisoprene) - havinghaving itsits isopreneisoprene Tenacity:Tenacity: ToughTough

SimpleSimple representationrepresentation ofof a rubberrubber moleculmoleculee

Cross-linkingCross-linking byby sulphursulphur atomsatoms hardens.hardens, oror vulcanizes.vulcanizes, ththee rubberubberr

Vulcanite 296 J. Gemm., 1991, 22, 5

Fig. 3. Granular brownish surface of the gutta­ Fig. 4. Smooth brown surface of the vulcanite percha brooch (Figure 1) illustrating the pendant shown in Figure 2. significant loss of its black coating.

Sectility: Readily pared with a sharp blade jewellery contains other jewellery components, Specific gravity: 1.20+ (depending on filler con­ such as metallic pins and clips, determination of tent) their specific gravity is usually impossible. Addi­ 'Spot'refractive index: SR 1.60/1.61 tionally, attempts to determine 'spot' refractive Lustre: Waxy-resinous (velvety) when freshly indices for vulcanite or gutta-percha jewellery can polished. Tends to become finely pitted with age. be somewhat difficult due to the complex shapes in Diaphaneity: Opaque which these materials are commonly moulded; the Solubility: Insoluble in water, alcohol, glycerol, solubility of gutta-percha in refractometer contact acetone, and aliphatic hydrocarbons; but somewhat liquid; and the presence of a pigmented coating on soluble in aromatic hydrocarbon solvents, such as gutta-percha jewellery that will not yield the true toluene refractive index of this material. Thermal stability: Will not soften without decom­ Therefore, the distinction between vulcanite and position in a flame. A judiciously applied hot point gutta-percha must be made on the basis of the will yield the acrid odour of burning rubber. following tests: 1. Hand lens and/or low-power microscopic exa­ Distinguishing gutta-percha from vulcanite mination As both thermoplastic moulded gutta-percha, ... looking for evidence of the black or brown and thermoset moulded vulcanite, have been used coated surface that is often partly missing to imitate Victorian jet jewellery, the challenge of from the greyish or brownish fibrous or positively identifying these relatively uncommon jet granular surface of gutta-percha (Figure 3). imitations should be of some interest and import­ In contrast, vulcanite is evenly coloured, and ance to practising gemmologists. of uniformly smooth texture throughout its Unfortunately, as most vulcanite or gutta-percha mass (Figure 4).

Fig. 5. Uncoated, crazed surface of the gutta­ Fig. 6. Response of the surface of gutta-percha to an percha brooch shown in Figure 1. applied hot point of 150°C. J. Gemm., 1991,22, 5 297

Fig. 7. Response of polished surfaces of gutta-percha and vulcanite to an applied drop of toluene. Note the extensive softening of the gutta-percha surface (A) compared with the minor softening of the vulcanite surface (B) - as indicated by the scratch.

Note: The uncoated surface of moulded ciously applied hot point and/or suitable solubility gutta-percha frequently crazes with test should provide the effective distinction be­ increasing age (Figure 5). tween gutta-percha and black vulcanite or 'ebonite! 2. A judiciously applied hot point test ... low heat (appx. 60°C) will readily soften A plea gutta-percha (Figure 6); As this research has been based on specimens of while, vulcanite and gutta-percha jewellery loaned from ... vulcanite will only char at much higher Australian collections, they may represent a biased temperatures, yielding the odour of burning sample of jet imitations. The author would be rubber. delighted to correspond with other gemmologists 3. *A judiciously applied solubility test who share an interest in these two uncommon ... a minute drop of toluene will rapidly soften organic gem materials. gutta-percha (Figure 7A); but only slightly soften the surface of vulcanite (Figure 7B). Acknowledgement Muller claims1 that ... 'Because vulcanite is The author is greatly indebted to N. Mackay, thermoplastic, only one cut is necessary in the chain Curator of Specimens for the Western Australian link which can then be opened when heated and Branch of the Gemmological Association of Austra­ slipped onto the next link and closed again. Thus lia, for the loan of study specimens of vulcanite and distinguishing jet from vulcanite chains is merely a gutta-percha; and to Helen Muller and her husband question of ascertaining whether the links have one for their helpful review of this paper. or two joins'... should be treated with caution; for it is most unlikely that thermosetting vulcanite also displays thermoplastic properties. One simply can­ References not join two pieces of thermosetting vulcanite 1. Muller, H., 1987. Jet. Butterworths, London. 125-9. 2. Goodman, A., Schilder, H., Aldrich, W., 1974. The history together by heat softening and fusing them with and molecular chemistry of gutta-percha. Oral Surgery, Oral hand pressure. Gutta-percha chains, on the other Medicine & Oral Pathology. 37, 954-61. hand, can be quite easily heat sealed at a working 3. Stecher, P.G., 1950. The Merck index of chemicals and drugs. temperature much below 100°C. 7th ed., vol. 1. Merck: Rahway. 456-9. 4. Anthony, L.P., 1944. The American textbook of prosthetic dentistry. Lea & Febiger: Philadelphia. 391-407. Conclusion 5. Blow, C.M., Hepburn, C., 1982. Rubber technology and As both moulded vulcanite and gutta-percha may manufacture. Butterworth Scientific, London. 26-7. be found imitating jet, gemmologist must be able to [Manuscript received 29 June 1990, revised 8 September effectively distinguish these materials. Careful 1990.] observation for the presence of a coating^ and a judi­ ~------=~ THTHEE GEMMOLOGICA GEMMOLOGICALL GEGEMM TESTIN TESTINGG OFOF GREA GREATT ThThee singl singlee organizatio organizationn for for everyon everyonee ~~ <~® We offeWe roffer a comprehensiv a comprehensivee rang rangee of gemmologica of gemmologicall service servicess to ou tor our membersmembers,, student studentss and andother otherss with with a commercia a commerciall or professiona or professionall interesinterest.t EDUCATIOEDUCATIONN The DiplomThe Diplomaa Cours Coursee in Gemmolog in Gemmologyy (leadin(leadingg to Fellowshi to Fellowshipp - FGA - )FGA) We takWee pridtakee pride in ou inr internationa our internationall reputatio reputan ations as a learnea learnedd societ socy dedicateiety dedicatedd to th eto promotio the promotionn of of gemmologicagemmologicall educatio educationn and th ande sprea the dspread of of gemmologicagemmologicall knowledge knowledge.. The DiplomThe Diplomaa Cours Coursee has bee hasn speciallbeen speciallyy compile compiledd into a into a seriesseries of teachin of reachingg module moduless that ar thate bot areh readablboth readablee and lavishl and lavishlyy ^" illustratedillustrated.* Thes eThese course coursess provid providee a comprehensiv a comprehensivee step*by«ste step-by-stepp guide guide to theto fascinatin rhe fascinatingg world world of gemmolog of gemmologyy and a nand opportunit an opportunityy to ear ton thearne covete the covetedd initial initialss FGA FGA- Fello - wFellow of the of Gemmologica the Gemmologicall Association Association.. INSTRUMENTSINSTRUMENTS,, BOOK BOOKSS AN ANDD SPECIMEN SPECIMENSS ThrougThroughh our Instrument our Instrumentss Divisio Divisionn we ar wee abl aree tableo suppl to supplyy gemmologicagemmologicall instruments instruments,* gemston gemstonee and jeweller and jewelleryy relaterelatedd books books,, audiovisua audiovisuall materia materiall and gemston and gemstonee specimensspecimens.* The showrooThe showroomm is ope isn opendurin duringg norma normall officeoffice hour shours when when exper expertt assistanc assistancee is available is available.. ASSOCIATIONASSOCIATIO NAND AN D LABORATORYLABORATOR Y BRITAINBRITAI N withwit anh ainterestn interes int gemstones.in gemstones .

By makingBy makin useg of us thee o fcomprehensive the comprehensiv cataloguee catalogu youe canyou order can orde goodsr good by mail,s by mail telephone, telephon e or faxo rfrom fax fro anywherem anywher in thee in world. the world . GEMSTONEGEMSTON TESTINGE TESTIN G THETH JOURNALE JOURNA OFL OF, ^ ANDAN RESEARCHD RESEARC H GEMMOLOGYGEMMOLOG Y A fullA gemstone full gemston e The ThJournale Journa is amongl is amon g identificationidentificatio andn and the mostthe mos respectedt inspecte of d of researchresearc serviceh servic is e is its typeits typ in thee in world. the world . offeredoffere to dmembers. to members .Papers Paper on sall o naspects all aspect s The ThGeme Ge Testingm Testin g of gemstoneof gemston researche researc h LaboratoryLaborator y are publishedare publishe d (established(establishe in d1925) in 1925 is superbly) is superbl ytogether togethe withr wit theh the equippedequippe withd wit UVh I visibleUV/visibl ande FTIRand FTI R proceedingsproceeding of ours of our spectspectrophotometersrophotometers, numerous, numerou X-rays X-ra y organization,organization branch, branc h unitsunit for sthe for identification the identificatio of npearls, of pearls and, and information,information book, boo reviewsk review ands abstracts.and abstracts . otherothe sophisticatedr sophisticate identificationd identificatio andn and AdvertisementsAdvertisement ares accepted are accepte at veryd at very research instrumentation. research instrumentation. reasonablereasonabl rates.e rates . DIAMONDDIAMON GRADINGD GRADIN G MEETINGSMEETING S We also offer a Diamond Grading facility We also offer a Diamond Grading facilityLectures Lecture by sBritish by Britis andh internationaland internationa l whichwhic is secondh is secon to dnone to non in thee in world the world. . experts are organized throughout the year Both CIBJO and GIA reports are experts are organized throughout the year Both CIBJO and GIA reports are bothbot in hLondon in Londo andn inan dthe in provinces. the provinces . available.available . -~~~ For further information on the services '.~ " ~',,,::'!';',J.!:""'" e.~u r~r'Y.~'~~ Vr1 r'I"~ For further information on the services -JL - - ^——,,c availableavailabl pleasee pleas usee theuse tear~off the tear-of couponf coupo n provided or contact Mrs Laine Durkin PIAMDNUNHlini provided or contact Mrs Laine Durkin on 071-404 3334 who will be pleased to »0tK on 071-404 3334 who will be pleased to assistassis you.t you . ,-jt-a* ' 27 Greville27 Grevill Street,e Street , LondonLondo ECINn EC1N8S 8SU U Telephone:Telephone 071·4043334: 071*404 333 4 Fax:Fax:071-404884 071·4048843 3 303000 JJ.. Gemm.Gemm.,, 1991,221991,22,5, 5

GemmologicaGemmologicall investigatioinvestigationn ooff a synthetisyntheticc spinespinell crystacrystall frofromm ththee SovieSoviett UnioUnionn John I. Koivula, Robert C. Kammerling and Emmanuel Fritsch, Ph.D.Ph.D.

GemologicaGemologicall InstitutInstitutee ooff AmericaAmerica,, 16616600 StewarStewartt StreetStreet,, SantSantaa MonicaMonica,, CaliforniaCalifornia,, USUSAA

AbstracAbstractt AAtt a falfalll 19819899 gegemm anandd mineraminerall shoshoww helheldd iinn A transparentransparentt purplish-repurplish-redd octahedraoctahedrall syntheticsynthetic DenverDenver,, ColoradoColorado,, U.S.A.U.S.A.,, MrMr.. BilBilll VanceVance,, a localocall spinespinell crystacrystall growgrownn iinn ththee SovieSoviett UnioUnionn wawass studied.studied. gemmologistgemmologist,, noticenoticedd twtwoo larglargee transparentransparentt intenseintense ThThee propertiepropertiess werweree investigateinvestigatedd ttoo determindeterminee iiff ththee reredd octahedraoctahedrall crystalcrystalss thathatt lookelookedd liklikee finfinee gemgem­- material could could be be identified identified using using standard standard gemmological gemmolo­ qualitqualityy spinelsspinels.. TheTheyy werweree iinn ththee possessiopossessionn ooff a gical tests. It was alsQ examined by means of energy tests. It was also examined by means of energy gentlemagentlemann frofromm ththee SovieSoviett UnionUnion.. MrMr.. VancVancee wawass dispersive X-ray X-ray fluorescence, fluorescence, UV-visible UV-visible spectrophotometry spectropho­ told that the crystals were 'synthetic spinel grown tometry anandd infrareinfraredd spectrometrspectrometryy ttoo documendocumentt thesethese told that the crystals were 'synthetic spinel grown properties. hydrothermallhydrothermallyy iinn ththee SovietSoviet Union'Union:. HHee wawass ablablee toto purchaspurchasee ththee smallesmallerr ooff ththee twtwoo crystalcrystalss bubutt wawass toldtold IntroductioIntroductionn thathatt ththee largelargerr ononee wawass nonott foforr salesale.. HHee wawass nonott ableable FoForr gemmologistsgemmologists,, so-calleso-calledd synthetisyntheticc spinespinel-l - iinn ttoo determindeterminee iiff thesthesee crystalcrystalss araree beinbeingg produceproducedd inin colourcolourss otheotherr thathann reredd - hahass neveneverr beebeenn considereconsideredd a quantitquantityy foforr commerciacommerciall salesale.. probleproblemm synthetic.synthetic. ThThee mass-productiomass-productionn ooff thisthis BecausBecausee ooff hihiss crystal'crystal'ss unusuaunusuall sizsizee anandd qualityquality materiamateriall hahass alwayalwayss beebeenn bbyy ththee flame-fusioflame-fusionn 'Ver­'Ver- MrMr.. VancVancee contactecontactedd ththee authorauthorss ttoo finfindd ououtt iiff neuilneuil'' processprocess,, whicwhichh requirerequiress thathatt excesexcesss aluminaalumina thithiss apparentlapparentlyy neneww typtypee ooff synthetisyntheticc mighmightt bbee ooff bbee presenpresentt iinn ththee structurstructuree (Nassau(Nassau,, 1980).1980). ThiThiss setssets interesinterestt foforr detailedetailedd gemmologicagemmologicall investigationinvestigation uupp a distinctivdistinctivee patterpatternn ooff internainternall straistrainn iinn thethe anandd description.description. boulebouless thatthat,, iinn cucutt stones,stones, iiss quitquitee easileasilyy recognizrecogniz­­ ItIt hahass beebeenn lonlongg knowknownn thathatt gem-qualitgem-qualityy spinelspinel ablablee inin a fieldfield ofof polarizedpolarized light.light. ThisThis distinctivedistinctive crystalscrystals havhavee beebeenn growngrown experimentallyexperimentally byby anomalousanomalous doubledouble refractiorefractionn hahass beebeenn variouslyvariously methodsmethods otherother thanthan flameflame fusion.fusion. InIn 18481848 J.J.J.J. calledcalled a 'cross-hatch'cross-hatch effect'effect' oror 'tabby'tabby extinction'extinction' byby EbelmenEbelmen waswas probablprobablyy thethe firstfirst toto successfullysuccessfully growgrow gemmologists.gemmologists. syntheticsynthetic spinelspinel inin a boratboratee fluxflux (Nassau,(Nassau, 1980).1980). TheThe ThisThis excessexcess aluminaalumina enrichmentenrichment alsoalso resultresultss inin anan bookbook "Color"Color EncyclopaediaEncyclopaedia ofof Gemstones"Gemstones" (Arem,(Arem, abnormallyabnormally elevatedelevated refractiverefractive indexindex andand a slightlyslightly 1987)1987) mentionsmentions flux-grownflux-grown redred andand blubluee syntheticsynthetic higherhigher specificspecific gravitygravity thathann woulwouldd normallynormally bebe spinel.spinel. OneOne ofof thethe authorsauthors hashas personallpersonallyy examinedexamined encounteredencountered inin mosmostt colourscolours ofof naturanaturall spinel.spinel. a collectioncollection ofof smallsmall pinkpink andand lightlight blueblue octahedronsoctahedrons BecauseBecause ofof this,this, untiuntill now,now, ththee separationseparation ofof naturalnatural growngrown byby a flux-meltflux-melt process.process. ButBut suchsuch methodsmethods ofof fromfrom mostmost syntheticsynthetic spinelspinel hahass beebeenn oneone ofof thethe crystalcrystal growthgrowth werweree consideredconsidered experimentalexperimental andand easiesteasiest andand mostmost straightforwardstraightforward ofof ththee synthetic­synthetic- werweree alwaysalways deemeddeemed tootoo costlycostly forfor thethe productioproductionn ofof versus-naturalversus-natural separationsseparations thatthat a gemmologistgemmologist isis syntheticsynthetic spinelspinel inin generalgeneral - particularlparticularlyy whenwhen likelylikely toto face.face. flame-fusionflame-fusion materialmaterial inin colourscolours otherother thanthan redred InIn thethe casecase ofof redred syntheticsynthetic spinel,spinel, however,however, thethe couldcould bebe producedproduced quitequite easilyeasily andand atat veryvery littlelittle ratioratio ofof Alz0A1203 toto MgOMgO mustmust bebe virtuallyvirtually identicalidentical toto cost.cost. thatthat foundfound inin naturenature (l(1 toto 1)1) iftheif the chromiumchromium dopantdopant A recentrecent ICAICA LabLab AlertAlert (Bank(Bank andand Henn,Henn, 1989)1989) isis toto givegive thethe desireddesired redred colourcolour (Nassau,(Nassau, 1980).1980). describeddescribed a flux-grownflux-grown syntheticsynthetic redred spinelspinel BecauseBecause ofof thethe variablevariable burn-offburn-off ratesrates ofof AlA1z2003 andand octahedronoctahedron weighingweighing 13.1413.14 carats.carats. AtAt 17.1917.19 caratscarats MgO,MgO, itit isis veryvery difficultdifficult toto growgrow redred syntheticsynthetic spinelspinel thethe crystalcrystal purchasedpurchased byby Mr.Mr. VanceVance isis thethe largestlargest byby thethe flame-fusionflame-fusion method.method. syntheticallysynthetically growngrown octahedronoctahedron yetyet studied.studied. AndAnd itsits WithWith fluxflux growth,growth, however,however, thethe chemicalchemical compo­compo­ colourcolour isis equalequal toto a finefine colourcolour inin naturalnatural redred spinel.spinel. nentsnents dodo notnot suffersuffer fromfrom high-temperaturehigh-temperature burn-offburn-off Therefore,Therefore, consideringconsidering thethe newnew (Soviet)(Soviet) source,source, andand symptomaticsymptomatic ofof flame-fusionflame-fusion growthgrowth aboveabove 2200°C.2200°C. inin viewview ofof thethe transparencytransparency andand pleasingpleasing redred colour,colour, SoSo thethe commercialcommercial growthgrowth ofof syntheticsynthetic redred spinelspinel byby a thoroughthorough gemmologicalgemmological investigationinvestigation waswas carriedcarried thethe flux-meltflux-melt methodmethod isis feasiblefeasible fromfrom a technical,technical, ifif out.out. notnot economic,economic, standpoint.standpoint.

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-12520022-1252 J. Gemm., 1991,22,5 301

Gemmological characteristics Ultraviolet fluorescence Under darkroom conditions the spinel crystal was examined against a non-fluorescent black back­ Crystal description ground using both long-wave and short-wave ultra­ Other than size, the first thing that strikes the violet radiation. Contrast control goggles were worn observer about this crystal is its obvious quality. It is to help eliminate secondary reflections. Samples of a transparent, near-perfect octahedron with one both natural red and pink spinel from Burma and truncated (cube face) tip so that the crystal can be Sri Lanka were used as comparison stones. balanced on point rather than resting on an The fluorescent reaction to long-wave radiation octahedral face (Figure 1). was a strong purplish to orangy-red that seemed to On a Mettler PC400C electronic diamond ba­ vary slightly with direction, while the short-wave lance, the spinel crystal was determined to weigh fluorescence was only slightly weaker, a moderately 17.193 carats with corresponding measurements of strong slightly orangy-red. Additionally, under 14.79 x 13.40 x 11.76 mm. short-wave, some of the edges between crystal faces appeared superficially chalky and, in certain direc­ Colour tions, yellowish-orange. There was no purplish The daylight colour could be described as an overtone under short-wave radiation. No phos­ intense slightly purplish-red. In artificial incandes­ phorescence was detected from either wavelength cent light, a very slight orange component was when the ultraviolet lamp was switched off. present. Under fluorescent illumination the orange With the exception of the slight chalkiness to component was eliminated and the purplish over­ short-wave, the fluorescence characteristics of this tone was somewhat stronger, resulting in a purp­ synthetic spinel crystal were almost identical to lish-red body colour. Direction of observation had those shown by the natural red and pink spinel no effect on the colour appearance as expected for comparison stones. an isotropic gem species. GIA GEM Instruments Color Master notation was C-20-11-18. Visible light spectroscopy A Beck prism spectroscope with an illuminated wavelength scale was used to determine the visible Refractive index light absorption characteristics for the synthetic The synthetic spinel crystal had sufficiently flat spinel crystal. Because of its euhedral octahedral octahedral faces to allow flat facet refractive index form and high transparency the crystal behaved as a readings to be taken. Using a Duplex II refracto- 'window' being ideal for transmitted light spectro­ meter and a near-monochromatic, sodium- scopy. The crystal showed general absorption in the equivalent light source, the refractive index was violet and blue from 400 to 450 nanometres, a determined to be 1.719. This value is within the diffused weak absorption band between 580 and range previously determined for natural spinel and 630 nm, a strong, fine line at 680 nm, and a strong as such does not offer any means of separation. fluorescent line in the deep red at 690 nm. Once again, because natural red spinels show Specific gravity similar absorption characteristics, visible light Methylene iodide, with a 3.32 specific gravity, absorption as observed through a hand spectro­ was used for standard sink-float testing to estimate scope is of no value in separating this synthetic specific gravity. The spinel crystal readily sank in spinel from natural gems of similar colour. this liquid when submerged just below the surface UV-visible absorption spectroscopy was per­ and released. When compared to the sink rate of an formed using a Pye Unicam 8800 spectrophoto­ 8.25 carat round brilliant flame-fusion synthetic meter. The spectrum of this synthetic as viewed sapphire, the spinel sank visibly slower. But its sink with the spectrophotometer is similar to that of rate was virtually identical to that of a 1.71 carat natural red spinel. However, the 'chromium lines', natural purplish-pink spinel crystal and to that of a which appear as two weak, sharp bands around 3.21 carat emerald-cut light blue flame-fusion 650 nm in the spectrum of natural red spinel, were synthetic spinel as well. just one, much broader band in the spectrum of Because of its weight and apparent quality, the the synthetic sample. synthetic spinel crystal's specific gravity was deter­ mined by hydrostatic testing. Three separate runs Chelsea colour filter reaction were carried out at room temperature. The average When the synthetic spinel crystal was placed on specific gravity for those three runs was 3.58 ± 0.01. the tip of a fibre optic illuminator and examined in This value for specific gravity falls within the range several directions with a Chelsea colour filter, the established for natural gem-quality spinel. colour through the filter was a strong orangy-red. 302 J. Gemm., 1991, 22, 5

Fig. 1. Transparent synthetic spinel crystal weighing 17.193 Fig. 2. Primary flux inclusions in the synthetic spinel crystal. carats reportedly grown in the Soviet Union. Photo­ Magnified 20 x. Photomicrograph by John I. Koivula. graph by Robert Weldon.

Fig. 3. The truncated surface that appears to be the point of Fig. 4. Brightly reflective and iridescent air-filled fractures attachment or growth-nucleation of the synthetic resulting from strain as observed in the synthetic spinel. Magnified 5x. Photomicrograph by John I. spinel. Magnified 10 x. Photomicrograph by John I. Koivula. Koivula. J. Gemm., 1991,22, 5 303

Fig. 5. Triangular etch features observed on the octahedral Fig. 6. Growth hillocks on an octahedral face of the flux- face of a natural spinel crystal. Magnified 80 x. Photo­ grown synthetic spinel crystal. Magnified 80 x. Photo­ micrograph by John I. Koivula. micrograph by John I. Koivula.

Natural spinels of similar body colour show virtual­ minute triangular etch pits (Figure 5) on their ly the same orangy-red colour when viewed through octahedral faces. The smooth-appearing octahedral the filter. This test therefore does not provide a surfaces of the synthetic crystal, however, were means of natural-versus-synthetic separation. covered with semi-circular growth hillocks (Figure 6) of a type not yet reported on natural spinel Magnification crystals. A standard gemmological microscope equipped Infrared spectrometry for a variety of illumination techniques, including The mid-infrared absorption characteristics of polarized light, shadowing and oblique illumina­ the synthetic spinel crystal were studied using GIA's tion, was used to study the synthetic spinel crystal Nicolet 60SX Fourier-transform infrared spectro­ both internally and externally. meter. The results of this testing showed that while Surprisingly, because it was represented as hyd- two very weak broad features were observed in the rothermal, the crystal contained what appeared to mid-infrared at about 3620 and 3375 cm-1, they do be primary flux inclusions of a deep orangy-brown not compare in intensity with the features observed colour with an angular to jagged profile (Figure 2). in hydrothermal materials. Additionally, no intense These inclusions formed a pyramid-shaped phan­ broad absorption centred at 3600 cm1 (indicating tom in near-perfect alignment with the external the presence of hydroxyl groups) was detected. faces of the octahedron that was centred just under Hydroxyl groups indicate the presence of water and the surface of the truncated octahedral tip. The have been observed in all natural and synthetic truncated surface was pitted and ridged in a manner hydrothermally-grown materials, including natural indicating that it was the surface of crucible attach­ and synthetic emeralds and amethysts. The absence ment during growth (Figure 3). of this feature rules out hydrothermal growth as the The crystal also showed some brightly reflective means of synthesis and indicates that the crystals and iridescent air-filled fractures (Figure 4) that were grown from a melt. The additional observation seemed to have their point of origin at or near the of inclusions typical of flux-grown synthetic mate­ phantom of dark inclusions. In polarized light, rials proved that this octahedral crystal was grown strain was observed in association with the fractures by a flux-melt technique. and flux-like inclusions suggesting that perhaps the pyramid-shaped phantom delineated the original Chemistry borders of a growth discontinuity and that the Using GIA's Tracor Northern Spectrace 5000 fractures are the result of strain. energy dispersive X-ray fluorescence system, a bulk Externally, closer inspection of the major crystal qualitative chemical analysis was done on the revealed three small secondary satellite modified synthetic spinel crystal. In addition to the expected octahedral crystals protruding in parallel growth magnesium, aluminium and chromium, trace from one octahedral face (cover picture). Most amounts of iron, nickel, vanadium and molybde­ natural spinel crystals which have not been sub­ num were detected. Molybdenum is a common jected to mechanical water erosion show either component of fluxes used to grow gem materials. virtually smooth surfaces or, on close inspection, Titanium, a common component of natural spinels, slight signs of chemical dissolution in the form of was not detected. 304304 J.J. Gemm.,Gemm., 1991,22,51991, 22, 5

ConclusionConclusion propertiesproperties suchsuch asas refractiverefractive index,index, specificspecific gravity,gravity, RedRed isis generallgenerallyy consideredconsidered thethe mostmost valuablevaluable UUVV fluorescence,fluorescence, spectrum,spectrum, etc.,etc., shownshown bbyy thesethese colourcolour ooff naturalnatural gemgem spinel.spinel. BecauseBecause ofof thethe preciseprecise syntheticssynthetics areare virtuallvirtuallyy identicalidentical toto thosethose propertiesproperties ratiratioo ofof magnesiummagnesium toto aluminiumaluminium requiredrequired itit hashas inin naturanaturall redred spinels.spinels. alwaysalways beenbeen veryvery difficultdifficult ttoo grogroww usinusingg thethe flame­flame- fusionfusion technique.technique. TheThe appearanceappearance ofof largelarge flux­flux- AcknowledgementsAcknowledgements growngrown syntheticsynthetic crystalscrystals,, however,however, maymay meanmean thatthat MikeMike MoonMoon inin GIA'sGIA's researchresearch departmentdepartment propro­­ facetedfaceted syntheticsynthetic redred spinelsspinels willwill becombecomee availableavailable videdvided thethe infraredinfrared spectralspectral datadata andand parpartt ofof thethe commercially.commercially. TheThe extentextent toto whichwhich thesethese flux­flux- qualitativequalitative chemicalchemical analysis,analysis, whilwhilee MeredithMeredith Mer­Mer­ growngrown syntheticsynthetic redred spinelsspinels areare beinbeingg manufacturedmanufactured cer,cer, alsoalso ofof thethe GIGIAA researchresearch department,department, performedperformed inin thethe SovietSoviet UnioUnionn (and(and marketed)marketed) isis nonott yetyet thethe UV-visibleUV-visible spectrophotometry.spectrophotometry. TheThe authorsauthors areare known.known. However,However, becausebecause largelarge crystalscrystals havhavee nownow thankfulthankful toto MrMr BillBill VanceVance forfor thethe loanloan ofof thethe beenbeen reportedreported iinn botbothh WestWest GermanyGermany (Bank(Bank andand specimenspecimen forfor thithiss study.study. Henn,Henn, 1989)1989) andand thethe UniteUnitedd States,States, itit isis possiblepossible thatthat therethere maymay bbee a seriousserious marketinmarketingg efforteffort onon a worldwide scale. worldwide scale. ReferencesReferences SoSo far,far, toto ourour knowledgeknowledge,, onlyonly largelarge transparenttransparent Arem, J.E.,J.E., 1987. 1987. Color Color Encyclopaedia Encyclopaedia of Gemstonesoj GemslOnes,, Van Van Nostrand Nos­ roughrough crystalscrystals havehave beebeenn seen.seen. ButBut facetedfaceted stonesstones ooff Reinholdtrand Company, Reinhold New Company, York, New New York. York, New York. highhigh clarityclarity weighingweighing severalseveral caratscarats couldcould bbee easilyeasily Bank,Bank, H.H.,, Henn,Henn, U.,U., 1989.1989. Flux Grown Synthetic Red SpinelSpinel cutcut frofromm suchsuch crystals.crystals. IfIf theythey are,are, withouwithoutt fluxflux From U.S.S.R.,U.S.S.R., lCAICA LaboratoryLaboratory AlerAlertt NumberNumber 2626.. inclusioninclusionss toto identifyidentify themthem asas synthetic,synthetic, theythey willwill bebe Nassau,Nassau, K.,K., 1980.1980. Gems Made by Man, ChiltonChilton BookBook Company,Company, Radnor,Radnor, fennsylvania.Pennsylvania. veryvery difficultdifficult forfor thethe jeweller-gemmologisjeweller-gemmologistt toto iden­iden­ tifytify becausebecause allall ofof thethe standardstandard gemmologicalgemmological [[ManuscriptManuscript receivedreceived 2626 January January 1990.J1990.] J. Gemm., 1991, 22, 5 305

Gemmological Abstracts

BENJAMIN, M., 1990. Letter. Imitation opalized than for natural morganite. The Biron synthetic has shells. Australian Gemmologist, 17, 7, 277-8. moderate orange fluorescence in LWUV. R. K.M. The dealer who supplied the opalized shell dealt with in the November issue of Australian Gemmolo- BROWN, G, 1990. Gemmological study club lab gist by John Koivula, states that their artificial report. Australian Gemmologist, 17, 6, 221-30, 22 structure was fully obvious both to him and to figs in colour (not sequentially numbered). Susan Johnson who passed them on to the GIA. Describes or investigates, oiled ruby; rainbow R.K.M. lattice sunstone; silicon imitating hematite; Keppel Bay variscite; quartz soude 'amethyst'; Dungowan BRACEWELL, H., 1990. Gems around Australia. (Tarnworth) nephrite; Aqua Aura; Australian pra- Part 3. Australian Gemmologist, 17, 7, 265-9, 15 siolite; B quartz, and Argentinian rhodochrosite. figs, mostly coloured. (Suggests that natural radiation has converted some Continuing the Round Australia search, the prasiolite to amethyst. Prasiolite is normally Hart's Range is dealt with, offering zircon, garnet, obtained by heating amethyst, and the heat of the feldspar, beryl, tourmaline, kyanite, epidote, ruby, tropical sun has been known to do this, so the report iolite and chrysocolla. Paper comments on dirty seems to indicate a reversal of that process.) R.K.M. condition and appalling language of young abo­ rigines (self-imposed problems), but aborigine BROWN, G, BRACEWELL, H., 1990. Mt Philp elders were gentlemanly and Mrs Bracewell found aventurescent iolite. Australian Gemmologist, 17, them a delight to deal with.. R. K. M. 6, 231-4,15 figs in colour. Located 55 km SE of Mt Isa, this deposit yields a BROWN, G, 1990. Some rare ivories. Australian deep blue iolite with inclusions of hematite Gemmologist, 17, 7, 256-62,23 figs. platelets, pinite, apatite (?), and a possible amphi- A dental expert deals with the rare ivories from bole. Constants are in line with Mt Isa iolites, the walrus, including fossil tusks preserved in Arctic hematite giving the Mt Philp material an aventures­ cold for perhaps 2000 years, crocodile teeth, tiger cent sheen. R. K. M. teeth, boar teeth and dugong tusks. R. K. M. BROWN, G, KELLY, S.M.B., BEATTIE, R., BROWN, G, 1990. The appropriateness of GAA's BRACEWELL, H., 1990. Gemmology study club gemmological nomenclature, 1990 Presidential reports. Australian Gemmologist, 17, 7, 279-86, 24 address. Australian Gemmologist, 17, 6, 216-18 figs, some in colour. and 248-50. Grahame Brown argues cogently for a common- The Club reports on a chalcedony with dendrites sense approach to naming gem substances and of copper minerals from Mt Isa which provides a decries the misuse of names which is apparently new ornamental material; a pair of mottled black- common in Australia. He summarizes rules laid dyed cultured pearls had been waxed; faceted down by the Commission set up by the Internation­ colourless calcite; natural pale yellow sapphire al Mineralogical Association and by CIBJO. He which had been heated to give the rarer colourless goes on to analyse the degree of acceptance and to variety; a purple triplet of colourless synthetic discuss the use of the word 'synthetic' and the often spinel; a diamond etched by heat; a colour-change confused multiplicity of names applied to synthe­ (purple to blue) didymium doped cubic zirconia; tics. Much of what he said applies world-wide. various new Russian quartz synthetics; turquoises R.K.M. with brecciated texture; reconstructed kauri gum carvings; scenic Peruvian common opal and a BROWN, G, 1990. Biron synthetic pink beryl. natural pearl necklace with a single imitation pearl Australian Gemmologist, 17, 6, 219-20, 2 figs. at its centre, a fair match which was easily detected A new synthetic morganite for which the author by lens. [Abstracter finds the unconventional quotes constants, SG 2.68 and RI 1.571-1.578, DR numbering of illustrations for this paper confusing 0.007, saying that these are 'considerably' lower and rather irritating. ] R. K. M. 306 J. Gemm., 1991,22,5

BROWN, G., LINTON, T., 1990. Treasure Chest gem Semi-transparent sodalite cut into some 2000 tester. Australian Gemmologist, 17, 7, 274-5, 1 fig. small beads looked very like synthetic sapphire; a 'Yet another' thermal conductivity probe which faceted pink spinel lacked octahedral inclusions but gives results which are 'probable' rather than 'posi­ had polysynthetic twin planes, oriented needles and tive', suitable for single diamonds but not for a bluish tone in transmitted light; an antique continuous use, nor for other species. R. K. M. looking Russian blue stone earring was paste, with old-cut diamonds and a post-revolution hallmark which dated it after 1917 (?); a blue three stone ring BROWN, G., SNOW, J., BRIGHTMAN, R., 1990. had deep Sri Lankan-cut synthetic sapphires set YAGG: a gemmology study club report (not with diamond chips (cleavage flakes?), the intact indexed). Australian Gemmologist, 17. 6, 239-42. silver and gold setting looked antique, but synthetic 10 figs in colour. sapphires were first made in 1910. R.K.M. A report on yttrium aluminium gallium garnet, Y3(Al,Ga)50i2 (doped with chromium), made by Dr J. Osman of JO Crystal Co, Calif. True silicates FRYER, C.W., ED., CROWNINGSHIELD, R., HOR- are viscous when melted and tend to finish as a WIT, K.N., KANE, R.E., HARGETT, D., 1990. glass. So these silica free 'garnets' are simpler to Gem trade lab notes. Gems & Gemology, 26, 3, synthesise. YAGG was made in a flux of lead and 220-7, 20 figs in colour. other oxides and imitated tsavorite, the green An 8.38 ct emerald dyed with green oil and with vanadium grossular garnet. 2000 carats were pro­ green dop wax on its girdle was detected, both duced before rising costs brought the enterprise to a enhancing the colour, poor chromium absorption halt. H 8+, SG 5.05, RI 1.88, Chelsea filter, bright and light pink through colour filter suggest a pale red, LWUV strong red, chromium spectrum, inclu­ stone artificially improved by the dye; a superb sions of yellow/brown flux, platinum(?) and veil­ chatoyant 31.04 ct carved horse head was identified like healed cracks. R. K. M. by spot RI 1.75 and by 445nm absorption band as chrysoberyl, carved in Idar-Oberstein. A light bluish-green diamond was identified as FRITSCH, E., SHIGLEY, J.E., ROSSMAN, G.R., MER­ electron irradiated by colour zoning around the CER, M.E., MUHLMEISTER, S.M., MOON, M., culet which was visible when the stone was im­ 1990. Gem quality cuprian-elbaite tourmalines mersed; a mottled 4.26 ct black diamond was from Sao Jose da Batalha, Paraiba, Brazil. Gems& natural with electro-conductive areas which sug­ Gemology, 26, 3,189-205, 18 figs in colour. gested type lib, but clear areas fluoresced blue to A detailed account of the exceptionally fine blue LUV and yellowish-green to SUV, confirming type and green copper-rich elbaite from Paraiba, Minas I diamond, probably the many graphite inclusions Geraes. RIs vary around 1.619-1.639, SG 3.04. accounted for colour and conductivity; a number of Some stones heated to convert bluish-purple to fine laser-drilled diamonds have resulted in cleavage green or blue, which colours are also found natural­ cracks and branched drill-holes, in one case the laser ly. R.K.M. hole reached an included diamond octahedron which would not be improved by such treatment FRYER, C.W., ED., CROWNINGSHIELD, R., HUR- (and inclusion could have been made more obvious WIT, K.N., KANE, R.E., HARGETT, D., 1990. if an air gap was created). Gem trade lab notes. Gems & Gemology, 26, 2, A Mexican opal had a large egg-like whitish 153-8. 18 figs in colour. inclusion, most obvious in transmitted light; a new 'Pearls' cultivated using mantle tissue without type of cultured pearl nucleus from Japan is nacre-producing cells, were coated with black/ illustrated, made from powdered oyster shell, plas­ brown calcareous concretion. A coral imitation was tic-bonded and coloured, it is used to nucleate black identified as barium sulphate, with plastic and or grey pearls, the nacreous layer is unusually colouring agent, 'spider-web'structure detected, RI translucent and drilling causes the binding plastic 1.58,SGabt2.33,H2to3. to melt. A diamond octahedron with etched channels is A necklace of natural fresh-water pearls of a dark illustrated; a rare purple diamond was type la A and brownish purplish-pink, from San Angelo lakes had no 550nm line. A yellow glass egg fluoresced and rivers in West Texas, selected over 15 years from strongly, very radio-active, probably uranium glass. many thousands found, is probably rare (but not An unusual banded lapis lazuli is illustrated. very attractive). Naturally black or grey Polynesian A grey baroque salt-water cultured pearl had its cultured baroque pearls were compared with similar bead markedly off-centre. A large old natural baroque blacks from Japan and were found to have baroque pearl had been trimmed up, half-drilled in larger nucleii. four places and a hole plugged with another pearl. Montana sapphire rough is being investigated to J. Gemm., 1991,22,5 307 determine whether it has been heat-treated or HUGHES, R., 1990. Talkin' 'bout gem testing instru­ surface diffused. A 63.65 ct colourless sapphire ments. Australian Gemmologist, 17, 6, 242-6. from Sri Lanka is described and illustrated, as is a A second instalment of rather flippant criticism natural cobalt spinel with colour change from blue of design, efficiency and high cost of Western to purple. R.K.M. gemmological instruments, this time on dichro- scopes, refractometers, immersion cells and stone Quo, J.F., WANG, F.Q., 1990. Chicken-blood holders. [It now seems possible that these papers stone. Australian Gemmologist, 17, 7, 262-5, 2 figs may be a preliminary hype for the author's declared in colour. intent to manufacture such items. Hopefully we Changhua, or chicken-blood stone is an altered may yet see well-designed, super-efficient instru­ silicic tuff rock, with cinnabar inclusions which ments produced by cheap skilled labour in Bang­ make it a fine red, a symbolic colour for the Chinese. kok, at prices suited to the pockets of hard-up Historically a seal stone, it is today used more for gemmologists the world over. Go to it Mr Hughes!] other carvings. H 2 to 3, SG 2.6 to 2.9, RI 1.53 to R.K.M. 1.60, waxey lustre, fine specimens rare and can command high prices. R.K.M. KANE, R.E., KAMMERLING, R.C., KOIVULA, J.I., SHIGLEY, J.E., FRITSCH, E., 1990. The identi­ HANANO, J., WlLDMAN, M., YuRKIEWICZ, P.G., fication of blue diffusion-treated sapphires. Gems 1990. Majorica imitation pearls. Gems& Gemolo- & Gemology, 26, 2, 115-33,23 figs in colour. gy, 26, 3, 178-88, 17 figs in colour. Surface-blued sapphires are increasingly preva­ Describes the history and products of Majorica lent. Near colourless faceted and polished stones are SA, a Spanish factory for imitation pearls of high packed in a powder of alumina and titanium and quality. Although these are said to be closely similar iron oxides, and heated for several hours at above to salt-water cultured pearls in appearance, detec­ 1700°C. This causes blue to diffuse into the suface tion is a simple application of the same tests as for to about 0.15mm, which in many stones has been other imitation pearls. R. K.M. increased to about 0.42mm by further heatings. The colour tends to penetrate more at facet junctions HARGETT, D., 1990. Jadeite of Guatemala: a con­ and around the girdle. High temperatures destroy temporary view. Gems& Gemology, 26,2,134-41, lustre and stones need repolishing, which tends to 10 figs in colour. remove blue unevenly. A fascinating account of the rediscovery of jadeite To the eye the stones look like normal well- by the Ridingers in the Zacapa region of Guatemala coloured sapphires, but breaks or depressions in the in 1974. Further discoveries were made and green, surface are not repolished and remain dark blue. 'blue', white, 'black' (dark green) and variegated High temperatures affect inclusions in the usual green, some with pyrite, are now known. Jadeite ways. was mined and greatly valued in several pre- The general blotchiness of colour is the main clue Colombian civilizations and their artifacts have to this treatment, and is best seen by the naked eye, been found from Peru to Mexico. The new material with the stones immersed in a glass dish of liquid is used to make copies of these, and as beads and over a strong but diffuse light source. Methylene cabochons. 'Black' material is most sought, but iodide (di-iodomethane) is the best liquid, but bluish jadeite is rarest. R. K.M. water or glycerine are also suggested. Geuda rough, which fails heat treatment to HLAING, U.T., 1990. Burmese zircon. Australian improve colour, is being fashioned and then given Gemmologist, 17, 6, 237-9, 3 figs. this blue-diffusion treatment. The stones are natu­ A short paper covering crystal proportions, heat ral but the thin layer of colour has been diffused treatment and analysis, not all of which is easy to synthetically and should be declared as such. Any follow. H.K.M. subsequent repolishing or re-cutting would largely remove it. R.K.M. HLAING, U.T., 1990. Myanmar diamonds from north to south. Australian Gemmologist, 17,7,278. KANE, R.E., KAMPF, A.R., KRUPP, H., 1990. Octahedral, trisoctahedral and hexoctahedral Well-formed tsavorite gem crystals from Tanza­ diamond crystals, often distorted and colourless, nia. Gems & Gemology, 26, 2, 142-8, 7 figs in found in alluvial areas near Mong-mit, Toungoo and colour. Mergui in Burma (Myanmar). (Those diamonds I Euhedral crystals of tsavorite are extremely rare, have seen from these regions have been small, but H. Krupp obtained several while on a visit to white, with exceptionally lustrous curved faces.) Tanzania. The gem is found in association with R.K.M. tanzanite on both sides of the border with Kenya. 308 J. Gemm., 1991, 22, 5

Gemmological properties are described, with blue in UV light, chrysoprase is normally inert; emphasis on the perfection of these crystals from good quality jadeite exists in Niigata, Japan, in the Karo-pit in the Merelani Hills. Stones up to 14 green, blue, purple, black and white but little is carats have been cut. R. K. M. mined owing to inaccessible terrain and bad cli­ mate, other deposits in Hokkaido and Hyogo KOIVULA, J.I., KAMMERLING, R.C., 1990. An prefecture also not exploited. unusual Indian aquamarine. Australian Gemmo- Idaho opal is assembled as cat's-eye triplets, with logist, 17, 7, 270-2, 5 figs. quartz or glass tops and chalcedony backs; San Found near Kangyam in Madras, this 41 ct Carlos Indian Reserve, Arizona, produces about aquamarine had constants within the normal range 600 kg cabochon grade peridot a month, October to for the material, with faint but anomalous absorp­ March, too hot other months, 15 kg small sizes are tion and strong pleochroism. Parts of the stone are facet grade; a Patagonian Jurassic chalcedony fossil so strained that they show biaxial figures with the pine cone is illustrated; while at Chantaburi, Thai­ conoscope. R.K.M. land, Dr H.A. Hanni of Switzerland, saw ruby rough reportedly from Vietnam, similar to Bur­ KOIVULA, J.I., BOEHM, E., KAMMERLING, R.C., mese, Pakistani and Afghan material - he feels that 1990. Diamond grit-impregnated tweezers: a heat treated this might rival Burma or East African potentially destructive gemological tool. Gems& ruby. Gemology, 26, 2,149-51, 6 figs in colour. A quartz, opal and pyrite rock found near Demonstrates the considerable damage done to a Lafayette, Louisiana, gives cabochons speckled ruby rotated just once with its table in contact with with play of colour; a yellowish-brown chatoyant these tweezers, which are unsuitable for any stone topaz was the first seen by News editors; Hector other than diamond, and even that can be scratched! Barbosa tells of his discovery of the Paraiba tourma­ R.K.M. line mine. Some tourmaline cat's-eyes examined in Idar proved to be doublets, clear tourmaline KOIVULA, J.I., KAMMERLING, R.C., 1990. Gem cemented to fibrous tourmaline base; they also news. Gems& Gemology, 26, 2 159-68, 16 figs in report assembled bi-colour tourmalines. colour. Synthetics and simulants Research for new synthetic materials of equiva­ Plastic cameos with backs misshapen like shell lent hardness to diamond calculates that a carbon cameos are illustrated; 'emerald' crystals from S. nitride would have almost the same bulk modulus. Africa were quartz with green cementing agent, A plant set up at Ipoh in Malaysia by Belgian coated with limonite and mica flakes, RI as for companies is processing 900,000 diamonds a year; quartz, spectrum indicated a dye similar to that Botswana produced 13 million carats in 9 months of used for stained jadeite, bubbles in soft cement and 1989, a new crushing plant at Jwaneng comes into a piece of emerald included in one 'crystal', these use soon. Intraco of Singapore join Russian Almaz were similar to fakes described earlier by Dr Hanni; to deal in diamonds, coloured stones, etc; a new 'rhodochrosite' beads, bought in Mexico, were Angolan field at Lucapa is being prospected; Argyle massive calcite, dyed pink, which left traces on an are training cutters near Beijing, China, to process acetone swab. R. K. M. Australian diamonds; kimberlite pipes are being drilled for diamond potential in Michigan; a joint KOIVULA, J.I., KAMMERLING, R.C., 1990. Gem Swiss/Sri Lankan project will cut diamonds and news. Gems& Gemology, 26, 3, 228-38, 15 figs in coloured stones at Katunayake free trade zone; colour. Mwadui mine, Tanzania, is expected to run out in Diamonds nine years and they are searching for more diamond News from Brazil; Botswana; Sierra Leone; pipes; Australian Molopo are prospecting for dia­ Australian prospecting in Hunan, China; Goa; monds and gold in Botswana by aeromagnetic India; Borneo; of Sri Lankan investment; Thai methods. auction of smuggled diamonds; new find of dia­ Coloured stones monds near Archangel'sk; Soviet visit to Israel A glass-capped plume agate doublet is described cutting plant; Israeli cutting in Warsaw and in detail; light emerald-green tourmaline from Bucharest, and widespread diamond exploration in Paraiba, Brazil, and greenish-blue apatite, claimed Australia. to come from the same area, seen at the Tucson Coloured stones Show, but apatite most likely Madagascan; some A fossil mushroom found in amber from The bluish-green apatite was sold as emerald in Kenya; Dominican Republic is an estimated 40m years old zoned white and green chrysoprase from Goias, and the best one known; a greenish-blue cat's-eye Brazil, investigated and found to fluoresce greenish- apatite is said to be a new variety; Zimbabwe J. Gemm.,1991,22,5 309

emerald mines are described; unusual greyish- found when placer mining for gold and platinum brownish-green chatoyant cabochon was identified group minerals in that area. R. K.M. as diopside, and a fine iolite cat's-eye is described and illustrated. KOVACS, E., 1990. Letter. Preliminary assessment A team of geologists have investigated Inner of gem identification system (GIS) software. Mongolia, China, and report many gem sites of Australian Gemmologist, 17, 7, 276-7. commercial significance. Argues case for computerized system. Editorial A chatoyant opal was unusual in being a true comment points out that expert computer program­ cat's-eye, with weak pleochroism; a chatoyant ming cannot substitute for training and experience. scapolite had two weaker light bands which make it R.K.M. effectively a star stone; an unusually carved tanza- nite is illustrated before and after heating to a blue LINTON, T., 1990. Radiation alert. Australian Gem­ colour; a rare tanzanite cat's-eye is also depicted; the mologist, 17, 7, 278. sugilite mine near Kuruman, S. Africa, is increasing Some Meltler balances B5, B6, and M5 imported production. into Australia before 1960 have been found to Aqua aura gold-film bluing of faceted gems is contain radium 226, but are unmarked as radiation now a commercial process; Mexican opal coated hazards. They should be withdrawn for expert with dark plastic on one side to enhance the play of decontamination. R. K. M. colour on the other, is described and the coating illustrated; and another opal had been sugar-treated LINTON, T., BROWN, G., 1990. Medo Hand and the entire stone coated with plastic, thicker on vacuum tweezers, model MH-100 and Linicon the base where an RI of 1.56 was obtained. LV-125 vacuum pump. Australian Gemmologist, Synthetics and simulants 17, 7,272-3, 2 figs. Prof. EO. Knischka of Steyr, Austria, reports A new approach to the problem of stones which producing synthetic ruby crystals over 5cm long, fly from conventional tweezers. Works well sucking capable of yielding cut stones of 67 carats, a half stones into a close hold, and blowing loose dust crystal of accordion-like stepped growth is illus­ from instruments. Weight 1.2 kilos, price $A295, trated and said to have glassy two-phased inclusions efficient but at DbA 60 at 1 metre, noisy! R.K.M. and platinum platelets, colours available - light, medium or dark Burmese or Thai purple. MITCHELL, R.K., 1990. Letter to the editor. Austra­ A fake emerald originating in Madagascar was lian Gemmologist, 17, 7, 275. submitted to Jean-Paul Poirot of the Paris labora­ A further note on the word 'profilated' in refer­ tory, who identified it as green fluorite roughly ence to 'profiled' bubbles in some synthetics, shaped to a hexagonal prism and cemented to pointing out that it was coined by our late and very tourmalinized rock by plastic mixed with mica, M. good friend Basil Anderson, and not by Robert Poirot points out that green fluorite has a similar Webster, another excellent but regrettably deceased absorption to emerald and is pink through the friend. (Author's abstract) R. K.M. Chelsea filter, but it fluoresces violet with LWUV and the cement fluoresced yellow/white. SCHMETZER, K., 1990. Hydrothermally grown A carved 'jade' sphere from Hong Kong proved to synthetic aquamarine manufactured in Novosi­ be a calcite/serpentine rock which had been selec­ birsk, USSR. Gems& Gemology, 26, 3, 206-11, 9 tively dyed in various shades of green and brown, figs in colour. and then waxed. R.K.M. A single specimen of Russian synthetic aquamar­ ine described in careful detail, had constants within KOPF, R.W., HURLBUT, C.S., KOIVULA, J.I., 1990. the normal range for natural material, but nickel Recent discoveries of large diamonds in Trinity from the stainless steel crucible was detected by County California. Gems & Gemology, 26, 3, spectrophotometer, while infrared spectroscopy 212-19, 7 figs in colour. proved hydrothermal origin. Tested stone con­ Former geologist and miner, Edgar J. Clark, tained many tell-tale inclusions which reduce its found four large diamonds of record sizes for acceptability as a gem. Absence of significant California in alluvial sand and gravel of the Hayfork amounts of sodium and magnesium also indicated Creek tributary of Trinity River, Northern Califor­ synthesis. R.K.M. nia, in the late 1980s. Weights 3.90,14.33,32.99 and 17.83, they were named Jeopardy, Serendipity, TRIOANI, T., 1990. Rare-earths. Australian Gemmo­ Doubledipity and Enigma, and were complex twin­ logist 17, 6, 235-6. ned crystals with encrusted faces, none of cuttable A brief account of the so-called 'rare earth' quality, but smaller gem quality stones have been elements. R.K.M. 310 J. Gemm., 1991, 22, 5

Book reviews

HUGHES, R.W., 1990. Corundum. (Butterworth component from yellow-green sapphires to give a Gem Books.) Butterworth-Heinemann, London. fine yellow) and development of yellow colour from pp. xviii, 314. Illus. in black-and-white and in white or pale yellow, mainly Sri Lanka material. colour. £35.00. The author makes the point that his information is Presumably out of deference to the importance of second-hand and speculatory - this is, of course, for the material described, this is a larger work than the reasons of commercial secrecy on the part of those others from the same Butterworth stable. This is carrying out the treatments. One anecdote illus­ one of the few monographs dedicated to a particular trates the dangers of treatment - read the book to species to be published in English during this find out the details! After describing irradiation and century and is welcome on that score alone. The other forms of treatment the author outlines current first chapter deals with the history of corundum, thinking on disclosure. with reference to early literature and, like succeed­ Synthetic and composite corundum are de­ ing chapters, includes its own bibliography. The scribed in chapter seven which is particularly second chapter describes chemistry and crystal­ exhaustive and contains a good bibliography. lography and here it is pleasing to see text diagrams Fashioning is described in the next chapter and taken from Goldschmidt's Atlas der Krystallformen; after sections on quality, famous stones and classi­ in this book the Goldschmidt diagrams have been fication, we come to the geology of corundum and relabelled and improved for the modern reader. notes on world deposits. It should be said that the Most gem monographs, for space reasons, have to section on classification contains a great deal of be sparing with this kind of illustration and they are information, particularly on Thai classification, not both useful and relevant here. previously published and most interesting. Prefer­ The book continues with physical and optical ence of different societies for particular colours is properties with useful notes on thermal expansion most valuable for dealers in corundum. and thermal conductivity, optical properties, col­ In the section on world deposits the history of the our, luminescence, absorption spectra (with notes deposits is given as well as the current situation so on the use of the hand spectroscope) and pleochro- far as this is known at the time of writing. Even ism. The effect of pleochroism on cutting is well better, different localities are given their own bib­ illustrated by text diagrams. liography. The book ends with an index. The chapter on inclusions follows and again This is a first-class book, well-printed and quite black-and-white photographs and text figures help well bound. All gemmologists should buy a copy. the reader even when he has the Gubelin inclusion M.O'D. books. Thai corundum is described particularly closely and since some of this material is the subject for enhancement this is a valuable feature here. Diagrams also show how primary fluid inclusions may be trapped in gemstones and illustrate zonal primary liquid inclusions; the healing of a crack is also usefully depicted. Nearly thirty pages are devoted to corundum enhancement and the reader will turn eagerly to this section in a book emanating from Thailand where so much treatment is carried out. Five major processes are listed for the heat treatment of corundum: they are removal of silk, development of silk, development of a blue colour from colourless material, removal of blue colour (the lightening of over-dark sapphires and the removal of the blue J. Gemm., 1991, 22, 5 311

Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices

OBITUARIES North West Branch It is with great regret that we announce the death On 17 October 1990 at Church House, Hanover of Sir Frank Claringbull, Ph.D., F.Inst.R, FGS, on Street, Liverpool, Mr Kenneth Scarratt, FGA, gave 23 November 1990, President of the Association a talk on the work of the Gem Testing Laboratory. and an Examiner for many years. A full obituary On 21 November 1990 at Church House the will be published in the April 1991 issue of The Annual General Meeting of the Branch was held, at Journal. which Mr W Franks, FGA, and Mrs Irene Knight, FGA, were re-elected Chairman and Secretary Mr Albert ('Bert') C. Colclough, FGA respectively. (D.1964), Rainham, died in October 1990.

Miss Jean G. Lumsden, FGA (D.1951), Edin­ burgh, died on 12 October 1990. ANNUAL GENERAL MEETING On 29 October 1990 at Goldsmiths' Hall, Foster NEWS OF FELLOWS Lane, London EC2, the Annual General Meeting of Mr Michael O'Donoghue spoke on gemstones The Gemmological Association and Gem Testing to the South East Branch of the National Associa­ Laboratory of Great Britain was held. tion of Goldsmiths on 18 October 1990 and to the Mr V.P Watson, FGA, chaired the meeting, and Sevenoaks Hard of Hearing Club on 27 November welcomed members to the first Annual General 1990. Meeting of the joint company. Mr Watson reported that the Laboratory had given a first class service Dr R.M. Key and Mr J.O. Ochieng gave a lecture during the year, including gem testing, diamond on 'Green garnets and blood-red rubies: a girl's best grading and consultancy work. Negotiations had friend in East Africa' at the British Geological taken place during 1989 for the Laboratory to be Survey, Edinburgh, on 17 December 1990. able to provide GIA Diamond Certificates, and this service came into operation in October of that year. MEMBERS' MEETINGS The Chairman thanked David Callaghan and Ken London Scarratt for the tremendous amount of work they On 14 November 1990 at the City Conference had undertaken during the year, particularly in Centre, Mark Lane, London, Mr John I. Koivula, connection with the proposed merger between the FGA, Chief Gemologist of the Gemological Insti­ Gem Testing Laboratory and the Gemmological tute of America, gave an illustrated lecture entitled Association. 'Recent developments and observations in gem- The Annual Report and Accounts were approved mology'. and signed. Sir Frank Claringbull and Mr R. Keith Mitchell Midlands Branch were re-elected President and Vice-President re­ On 26 October 1990 at the Society of Friends, Dr spectively. Johnson House, Colmore Circus, Birmingham, Mr Messrs D.J. Callaghan, N.W. Deeks, N.B. Israel, Alan Hodgkinson, FGA, gave a lecture entitled E.A. Jobbins, I. Thomson, V.P Watson, K. Scarratt 'Leave the moth in the diamond'. and Dr R.R. Harding, were re-elected to the On 16 November 1990 at the Society of Friends Council of Management. Mr Roy Huddlestone gave a lecture entitled 'The Messrs Hazlems Fenton were appointed Audi­ Cobra emerald mine in the Transvaal'. tors, and the proceedings then terminated. 312 J. Gemm., 1991, 22, 5

REUNION OF MEMBERS AND PRESENTATION OF AWARDS

Fig. 1. Tully Medallist Kathryn Anne Jarvis, receiving her award from Mr Eric Bruton.

The Annual Reunion of Members and Presenta­ ADDRESS BY MR ERIC M. BRUTON, FGA tion of Awards was held on 29 October 1990 at 'It is a pleasant experience to be faced by so many Goldsmiths' Hall, Foster Lane, London EC2. Mr successful people. You're lucky too. Not, of course, David Callaghan presided and welcomed those to have passed your examinations. I know you had present, which this year included award winners to work hard to do that. As if we didn't know it, it from Canada, Finland, France, Greece, India, was confirmed to me in an unlikely way last week. Kenya, The Netherlands, Spain, Switzerland and 'I was on a course. Nothing to do with gemmolo- the USA. Mr Callaghan thanked the Worshipful gy. No one there knew I had any connection with it, Company of Goldsmiths for allowing the Presenta­ or even what I did for a living. At lunch one day, I tion to be held once again in Goldsmiths' Hall, was talking to the man next to me. From North­ which had been closed for the past two years for umberland he was. He said: "I don't suppose you've refurbishment. ever heard about it, but there's a thing called Mr Callaghan reported that the 1990 Examina­ gemmology" (he called it gem-nology, like most tions had been held at 61 centres in 24 countries. people who never heard of it). He went on to say that Mr Callaghan then introduced Mr Eric M. Bru­ he'd been sailing and one of the crew was taking an ton, FGA. He said that as well as being Editor of the examination. It was terribly hard, there were so Retail Jeweller, the author of Diamonds and other many different subjects and he'd failed the first books related to the jewellery trade, Mr Bruton has time. I think he must have succeeded this time and also written many books on crime. He has been an is possibly here tonight. Examiner for the Association for a number of years, 'I mention this for two reasons. The first is that and has done a tremendous amount of work on the knowledge of gemmology is spreading, albeit very new Diamond Course. After making the presenta­ slowly. It is shown by the people who now come on tions, Mr Bruton delivered the address which is gemmology courses. You would of course expect printed below. those connected with the jewellery trade. And all The vote of thanks was given by Mr Noel Deeks. those directly related, like jewellery designers, J. Gemm., 1991,22,5 313

craftsmen, manufacturers and lapidaries. And those to whom a knowledge is valuable, dealers and brokers. Also related are geologists and mineralo­ gists, even archaeologists. We've had a scientific worker in a government archaeological laboratory. We've had antique dealers, auctioneers, diamond sorters, insurance assessors, as well as the true amateurs who have discovered the spell of gems but otherwise have no connection with them or with jewellery. 'Oh, I forgot Customs officers! Way back in the 1960s, my wife and I were invited to stay with some tea broker friends in Ceylon. Naturally I took the chance to visit as many mines and gemmologists as possible. One day I was introduced to a prominent jeweller and gem dealer in Colombo. I asked him if he had a padparadschah sapphire as I'd never seen one. "Yes", he said, "yes I have". But I'd have to come back another day to see it. I supposed it was in a safe deposit elsewhere. But he continued, "If you are coming back tomorrow, you can see it then. Today it is under the floorboards... This afternoon Fig. 2. Anderson/Bank Prize winner Susan Clark. we are having a secret raid by the Customs Depart­ ment." unscrupulous gem dealers were recycling the same 'A day or two later we were having breakfast when parcels of gems to change large sums of rupees into the 'phone rang. My friend said, "It's for you. The dollars or pounds. Anyway I went. Mr Da Silva was Chief Customs officer, Mr Da Silva. Can you go and friendly, which was a relief. He' heard I was on the see him this afternoon?" A nasty shock for breakfast Council of the Gemmological Association. I have time. Naturally I thought there had been some absolutely no idea how. He led me into another mistake, but couldn't imagine what I'd said or done room where there were, I think, eight of his officers to interest the Customs. Except that I'd been asking lined up. He introduced them one by one. Every a lot of questions about 'FEECS', a government one of them was an FGA! He said there were more scheme to encourage exports by letting the exporter FGAs in Customs than in the whole of the gem trade retain some hard currency. I'd found out how some in Ceylon!

Fig. 3. The Rayner Diploma Prize winner Michele Corne Halstenbach. Fig. 4. The Rayner Preliminary Prize winner Spencer Benham. 314 J. Gemm., 1991, 22, 5

'A sequel was that the padparadschah jeweller moment you're 'there' when you get your diploma. asked me to swap a refractometer for an ancient Above all you will begin to find that learning is very bronze statue of Queen Kuveni. His youngest son enjoyable and you never, never, get bored. You was taking the Association's correspondence course young people have a bigger incentive to learn than and couldn't get a refractometer because of the any past generation. If you've read your newspapers exchange restrictions! I did of course. His son got you'll know that there is a rapidly increasing his FGA and I've still got Queen Kuveni. demand for skilled younger people in business. This 'Probably the most dedicated gem student ever will continue into the foreseeable future. More than was a Japanese. What we call a "mature student". To ever before, those who succeed are those who have study for his gemmology exams in London, Mr learned how to learn. Nemo to left his wife in charge of his jewellery shops 'Well, I hope you hear and note what I say. There in Japan for around four years, only returning is only one absolute certainty in this world. Every­ occasionally. Apparently in Japan, the basic English thing CHANGES. It is the only fact you can rely on course teaches the letters of the alphabet and how to absolutely. That means you have to change too. On write and understand words and sentences. If you that note, it only remains to wish you well and every want to speak English, you have to take another success from all of us.' course. Mr Nemoto had only done the first course. So he couldn't really talk to anyone and certainly GEM DIAMOND EXAMINATION 1990 couldn't understand the lecturers. He made friends In the 1990 Gem Diamond Examination 41 with some of the other students and used to copy candidates qualified, 4 with Distinction. The names out their notes in the evenings. A big problem was of the successful candidates are as follows: understanding diagrams. But he graduated, became an FGA, and went on to get his Diamond Diploma. Qualified with Distinction Later he wrote out his impressions of Britain and Bourdillon, Catriona, London. the courses in longhand and had photocopies Plumb, Helen L., London. bound, which he brought to some of us who had Ruiz Belver, Antonio J., Barcelona, Spain. instructed him. He still couldn't speak a sentence. Vidal Ramia, Enriqueta, Barcelona, Spain. One inexplicable diagram in the book was a cross- section of the Scottish Highlands. Perhaps he got it Qualified mixed up with his inclusions! Andrews, Suzanne, London. 'Many outsiders are surprised at the varied Arnau Graus, Concepio, Barcelona, Spain. subjects, a basic knowledge of which is needed for Arranz Garcia, Felix, Barcelona, Spain. exams in gemmology. They may well be qualified in Barbara Sole, Rosa, Barcelona, Spain. one or another of them. Barrabes Lacarda, Silvia, Barcelona, Spain. 'I said at the beginning that I was on a course last Bassioudis, Vassilis, Thessaloniki, Greece. week and had another point to make. Having got Bauco, Robert, London. through the basics, it's much easier to keep on Blasco Jimenez, Josep, Barcelona, Spain. learning. Don't let it drop. Read the journals, take Bofill Montoro, Ana, Barcelona, Spain. other courses if you can. Above all keep asking Boira Roges, Berta, Barcelona, Spain. questions of people who're supposed to know. Very Caycedo, Miguel J., Ilford. often you'll find they don't. So try to find out for Duckett, Karen L., Long Preston. yourself. It's surprising how a simple question Ferguson, Neil E, Balloch. about something we take for granted can open up a Fuller, Mark R., London. surprising number of doors. I had that experience a Garcia Ferrandiz, Javier, Barcelona, Spain. couple of years ago. When you're examining a Garty, Anne M., Dundee. diamond, at certain angles you get an intense flash Hossen, Iqbal H., Mauritius. of light. Anyone who grades diamonds has seen it. I Hughes, David J., Cardiff. tried to work out how this happened in some detail Isern Truy, Enric, Barcelona, Spain. but got into trouble, so I asked a specialist on the Jain, San jay, Southall. behaviour of light. A few days later he rang back to Keys, Malcolm H., Manchester. say it wasn't as simple as it had first appeared. The Laborda Ferrer, Ma Angeles, Barcelona, Spain. cause of the flash was very complex and involved Law, Patricia M., London. with the two planes of polarization. So he was Lazaro Anglada, Ma Jose, Barcelona, Spain. writing a scientific paper about it. You can ask MacKinnon, Amanda L., Birmingham. questions like that. Commercial as well as scientific Mariona de Urquijo, Victoria E., Barcelona, Spain. ones. Meigh, Melanie J., London. 'You never can stop learning. Don't think for a Morris, David C, Whitfield. J. Gemm., 1991, 22, 5

Osborne, Sean J., London. Qualified-UK Patel, Pankajkumar, Manchester. Anver, Mohamed E, London. Santacreu Rull, Montserrat, Barcelona, Spain. Baldock, Janine R., London. Taylor, Richard R, Shrewsbury. Barker, Damon A.N., Winchester. Usechi Espinosa de los Monteros, Amp, Barcelona, Bing, Sara V., Exeter. Spain. Bowler, Simon R., Birmingham. Vataru, Monica, London. Burt, Peter O.K., Deal. Velaz Azpilicueta, Mercedes, Barcelona, Spain. Byrne, David M., Birmingham. Vildiridis, Athanassios, London. Charatan, Ivan L., London. Worthington, Sally L., Bradford. Cloke, Deborah J., Sevenoaks. EXAMINATIONS IN GEMMOLOGY 1990 Colomb, Nanette D., London. In 1990 Examinations in Gemmology, 551 candi­ Copestick, Bruce J., Harpenden. dates sat the Preliminary examination, 335 (61%) of Davidson, Anthony, Newcastle on Tyne. whom qualified, 398 candidates sat the Diploma Dietz, Susanne C, Birmingham. examination and 197 (49%) qualified, 10 with Downer, Martyn D., London. distinction. Edwards, Susan M., London. The Tully Medal for the candidate who submits Farrett, Kirs ten J., Dover. the best set of answers in the Diploma examination Farthing, Russell, Colchester. which, in the opinion of the Examiners are of Fitzmaurice, Karl M., Glenamaddy. sufficiently high standard, was awarded to Kathryn Gademsetty, Subba R., London. Anne Jar vis of Vancouver BC, Canada. Gibson, Bracken G, London. The Anderson/Bank Prize for the best non-trade Green, Sheila M., Glasgow. candidate of the year in the Diploma examination Henry, John M., Bolton. was awarded to Susan Clark of London. Hinds, Andrew E, Rickmansworth. The Rayner Diploma Prize for the best candi­ Hollanders, David J., Maidenhead. date of the year who derives her main income from Inkpen, Michael S., Kingsbridge. activities essentially connected with the Jewellery Jhaveri, Devang, London. trade, was awarded to Michele Corne-Halstenbach Jones, Colin P, Birmingham. of Geneva, Switzerland. Johnston, Paul W, Belfast. Jordan, Lynn P, Manchester. The Anderson Medal for the best candidate of the year in the Preliminary examination was Komppa-Vigar, Leena, Ampthill. awarded to Nicholas Nicolaidis of Harare, Zim­ Lamb, Lois N., London. babwe. Lancaster, Wendy, London. Levy, Aaron N., London. The Rayner Preliminary Prize for the best Lithiby, Jonathan P, Kingston-upon-Thames. candidate under the age of 21 years on 1st June 1990 who derives his main income from activities essen­ Liyanage, Don C.S., Ashford Common. tially connected with the Jewellery trade was Lloyd, Susannah M.D., Chester. awarded to Spencer Benham of Isle of Man. Lynch, Kieran J., Coventry. Mallett, Gillian E., Cambridge. Mann, Alexandrina E., Nottingham. DIPLOMA Matthews, Lisa J., Winchester. Meigh, Melanie J., Pains wick. Qualified with Distinction McCosh, Samuel M., Birkenhead. Aryatilake, Bamunuarachchige, Maharagama, Sri Offord, Philip A., Chandlers Ford. Lanka. Oldershaw, Caroline J.E., Penn. Clark, Susan W, London. Parkhill, Melanie J., Broadway. Corne-Halstenbach, Michele, Geneva, Pettigrew, Louise, Eaglesham. Switzerland. Piatt, Karen K., London. Huegi, Michael E, Gumligen, Switzerland. Rackley, Trevor, Wantage. Jarvis, Kathryn A., Vancouver, Canada. Ripley, Thomas, Stockton-on-Tees. Marcos-Pascual, Celia, Oviedo, Spain. Sanson, Steven N. J., London. Pyzowski, Carl C, Frackville, Pa., USA. Saywell, Neil, Nottingham. Rodriguez-Fernandez, Margarita, Ujo-Asturias, Shammas, Siham, London. Spain. Sim, Evelyn, Singapore. Vorasaph, Tracy, Bangkok, Thailand. Sinclair, Lesley, Stenhousemuir. Willmott, Keith R., Colombo, Sri Lanka. Smith, Karen, Dewsbury. Weixuan, Yen, Wuhan, China. Smookler, Sheryl, London. 316 J. Gemm., 1991, 22, 5

Spencer, Stephen R., Nottingham. Ip, Ting Cheong, Kowloon, Hong Kong. Spink, Michael C, London. Ishikawa, Noriko, Koto-ku, Tokyo, Japan. Tock, Graham B., Hull. Janse, Theodora J., Schiedam, The Netherlands. Van Heesewijk, Jacqueline, London. Javeri, Anjali J,, Bombay, India. West, Kenneth J., Hove. Jhaveri, Hina Sushil, Bombay, India. Wilson, Nean E., Longniddry. Jinbo, Kazuko, Kita-ku, Tokyo, Japan. Woodham, Sharon, Lichfield. Jones-Brunet, Catherine, Mississauga, Ont., Wright, John C., Solihull. Canada. Wright, Michael J., Watford. Jones-Napier, Pennye K., Washington DC, USA. Jordi, Ibafiez, Pueyo, Barcelona, Spain. Qualified - Overseas Kangas, Anne K., Helsinki, Finland. Alejo, Diedre K., Kowloon, Hong Kong. Kermorgant-Abily, Claire, Hong Kong. Argirakou, Ioulja, Volos, Greece. Kinev, Kathryn A., Atlanta, Ga., USA. Aulosalo, Liisa, Eura, Finland. Kung, Kwai, Kowloon, Hong Kong. Beentjes, Theodorus PC., Uitgeest, The Lai, Sau Ha Melody, Kowloon, Hong Kong. Netherlands. Lai, Tik Shan Sana, Hong Kong. Berlioz, Roger E, Kandy, Sri Lanka. Lam, Yick Man Raymond, Kowloon, Hong Kong. Bernad Soria, Jose M., Zaragoza, Spain. Lamahewa, Ranjith, Idar-Oberstein, Germany. Carlos Bertolin, Marti, Barcelona, Spain. Lees, John A., Waterford, VA, USA. Bolario Cid, Jordi, Barcelona, Spain. Leong, Kei Tong, Hong Kong. Boyer, Alice M., Silver Spring, Md., USA. Liao, Xiangjun, Wuhan, Hubei Province, China. Bubshait, Ahmed I., Manama, Bahrain. Li, Yali, Wuhan, Hubei Province, China. Canty, Gavin, Papatoetoe, Auckland, New Lo, Mun Shan Ivy, Hong Kong. Zealand. Lonka, Valtteri, Kuopio, Finland. Cardo Sabater, Elisabeth, Barcelona, Spain. Lopezi Gracia, Anna Ma, Barcelona, Spain. Carter, Maurice W, Toronto, Canada. Lui, Kin Wah Kelvin, Hong Kong. Casas Royo, Jose A., Alfaro (La Rioja), Spain. Luzondo Olea, Blancanieves, Barcelona, Spain. Cases Canes, Josep R., Barcelona, Spain. Ma, Kiu Chu Kitty, Kowloon, Hong Kong. Chan, Lais Sim Luisa, Hong Kong. Martinez Bautista, Santiago, Barcelona, Spain. Chen Xiugin, Wuhan, China. Matsumoto, Tamio, Minato-Ku, Tokyo, Japan. Chow, Marianne, Toronto, Canada. Montgomery, Richard S., South Sathorn, Chu, Sin Yi Christine, Kowloon, Hong Kong. Bangkok, Thailand. Cogan, Joanne M., Omaha, Nebraska, USA. Moreno Rastrero, Eduardo, Logrofi, Spain. De Jonge, Martin L., Nieuwegein, The Mustchin, Vivienne, Birkdale, Auckland, New Netherlands. Zealand. De Kam, Anneke, Rotterdam, The Netherlands. Naken, Tomoko, Kita-Ku, Tokyo, Japan. Desir Valen, Aline, Zaragoza, Spain. Nazareth, Christopher T, Bombay, India. Dorab, Brian I., Hong Kong. Oza, Bhagvat M., Bombay, India. Druguet Torner, Maria E., Barcelona, Spain. Paez Martinez, Ma Lluisa, Barcelona, Spain. Einstoss, Philip M., Toronto, Canada. Pandya, Neesha N., Bombay, India. Farkas, Susan, Vancouver BC, Canada. Parker, Duncan, Toronto, Canada. Fernandes, Bevelyn E., Bandra, Bombay, India. Patterson, Debra A., Toronto, Canada. Fu, Lintang, Wuhan, Hubei Province, China. Pehkonen, Kaarina A., Helsinki, Finland. Fung, Wai-Yin, Hong Kong. Perez Barrera, Jose Luis., Barcelona, Spain. Gini, Aspasia, Byron, Athens, Greece. Porebska-Brozyna, Dorota., East Rutherford, NJ, Gonzalez, Marie C. Y, Hong Kong. USA. Goyal, Sanjay S., Bombay, India. Premarathna, Hennayake M.S., Maharagama, Sri Gunaratne, Ananda Lakshman, Kundasale, Sri Lanka. Lanka. Qi, Lijian, Wuhan, Hubei Province, China. Hayakawa, Taketoshi, Kanagawa Pref, Japan. Ranatunga, Wasla M.T.K.B.R., Idar-Oberstein, Holen, Yvonne, Utrecht, The Netherlands. Germany. Hoogeboom, Paulus Nicolaas, Hoogland, The Ratnakumara, Dodangodage, Nugegoda, Sri Netherlands. Lanka. Huerta, Sanchez Ana Ma, Barcelona, Spain. Reveliotis, Christos, Athens, Greece. Hui, Wah Kam, Kowloon, Hong Kong. Roberts, Anne M., Kowloon, Hong Kong. Hui, Wai Kwong, Hong Kong. Rudolphij, Willemiene PC, Schoonhoven, The Hung, Chi Ling Vivian, Hong Kong. Netherlands. J. Gemm., 1991,22,5 317

Ruiz Domenech, Anna M., Torredembarra, Spain. Clark, Susan W, London. Schell, Martin A., Nonthaburi, Thailand. Clayton, Paul N., Wetherby. Seufert, Karin G., Amsterdam, The Netherlands. Cochran, Marian E., Blackpool. Shah, Anurag D., Nairobi, Kenya. Collins, Heather, Coatbridge. Shibata, Hirofumi, Osaka, Japan. Collins, Stephanie, New Maiden. Skilton, Margaret, Pakuranga, Auckland, New Colomb, Nanette, London. Zealand. Combe, Ian, Haddington. Soung, Min Hee, Busan, Korea. De Silva, Nihal G., Mitcham. Suno, Michiko, Kobe-City, Hyogo Pref, Japan. Dietz, Susanne C, Kidderminster. Tan, Min, Wuhan, Hubei Province, China. Duff, Wayne A., Harrow. Temelcoff, Catherine E, Toronto, Canada. Durlacher, Noel H., London. Terpilak, Thomas J., Bethesda, Md., USA. Euangelou, George C, Enfield. Tuovinen, Petri, Kouvola, Finland. Flint, Sara E., Leeds. Tsui Hiu Ying, Jeanie, Kowloon, Hong Kong. Fromming, David E., Aylesbury. Ueta, Kohei, Kochi-Ken, Japan, Gademsetty, Subba R., Chigwell. van Acker, Alain A.A.M., Tilburg, The Gallagher, Aileen, Wolverhampton. Netherlands. Gemmell, James, Havant. Vakil, Hetal H., Bombay, India. Gordon, Mark I., London. Vartiainen, Risto K., Rovaniemi, Finland. Graham, Barry D., Glasgow. Vela Clemente, Fernando, Binefar, Spain. Grant, John, Colchester. Velthuizen, Irmine H.S., Arnhem, The Grant, Miranda J., Edinburgh. Netherlands. Green, Allan A., Oxford. Vilabella Fernandez, Ramon, Barcelona, Spain. Green, Christopher M., Slough. Wang, Manjun, Wuhan, Hubei Province, China. Hamilton, Sandra L., Southampton. Weston, Amy L., Baltimore, Md., USA. Hamp-Gopsill, David, Burton-on-Trent. Wong, King Suen, Kowloon, Hong Kong. Hanafi, Safluat M., London. Wright, Wendy E., Toronto, Canada. Hare, Rebecca M.A., Fleet. Wu, Haiou, Wuhan, China. Hendry, Adrian L., Stansted. Yau Wai Ling, Janet, Hong Kong. Henn, Christopher J., Tong, Nr. Shifnal. Zeeman, Walentin, Bunnik, The Netherlands. Henry, John M., Bolton. Zhang, Liangju, Wuhan, Hubei Province, China. Hering, Peter J., Cambridge. Zoeter-Johannes, Simon, Rotterdam, The Hills, Margaret A., Tonbridge. Netherlands. Hobbs, Peter G.A., Lavenham. Zugazagoitia Urresti, Aitor, Durango, Spain. Hopper, Geoffrey C, North Harrow. Hunter, Charlotte T, Northampton. PRELIMINARY Jain, Neerja, Birmingham. Qualified-UK Jones, Stephen W, Carnetown, Mid Glam. Adams, Suzanne, Sutton. Judd, Guy A., Peterborough. Adams, Philip J., Staffordshire. Jupp, Thomas H., London. Allani, Magda, London. Jurukov, Vasil, London. Anderson, Nicola M., Falkirk. Kejriwal, Bindu, London. Antoniou, Lucas G., Barnet. Khimji, Priti, London. Anver, Mohamed E, Harpenden. King, Margaret A., Glasgow. Arnull, Edward E., Romford. Laklia, Andrew T, Greenhithe. Bailey, David E., London. Laurie-Lynch, Carl A., Birmingham. Bailey, Lisa J., Birmingham. Leathley, Adam B.D., York. Balducci, Annette L., Neston. Lee, Mary F.A., Addle stone. Ball, Chantal, Cheltenham. Leonard, Anri B., London. Ball, David J., Cheltenham. Lithiby, Jonathon P., Kingston Hill. Barrett, Nicola J., Sutton-in-Craven. Long, Ann D., Colchester. Benham, Spencer H., Onchan, Isle of Man. Lowe, David J., Colchester. Blackwell, Barry Q., Bexhill-on-Sea. Maclntyre, Jacqueline N., Edinburgh. Boyd, Heather K., Manchester. Madden, Adrien M., Harrogate. Bradley, Michelle A., Norwich. Mason, Alec J., Retford. Briggs, Harry J., London. Matthews, Lisa K., London. Burgess, Ian D., London. Michelson, Max J., Lincoln. Corrall, Corrall E., London. Mildenhall, Caroline, Kemp Town, Brighton. 318 J. Gemm., 1991, 22, 5

Mistry, Dharmesh, London. Blancardi-De Jong, Iris S., Sospel, France. Mitchell, Beverly J., London. Bosque Moral, Luis, Barcelona, Spain. Model, John E., Hatfield. Campos Novergues, Begona, Barcelona, Spain. Moydakis, Vaji L., Burnage, Manchester. Casacuberta i Ramirez, Josefina, Barcelona, Spain. Nash, Helen E., Slough. Chan, Bonnie Suk Kwan, Hong Kong. Nishino, Kiyoshi, Canterbury. Chan, Catherine Siu Man, Kowloon, Hong Kong. Offord, Philip A., Chandlers Ford. Chan, Chi Keung, Kowloon, Hong Kong. Ogden, Anne-Marie, Ealing. Chan, Francis Chi Man, Kowloon, Hong Kong. Papaceit, Gloria B., London. Chan, Keziah, Hong Kong. Patel, Pankaj, Wembley. Chan, Lai Sim, Hong Kong. Pattni, Dipesh S., Loughborough. Chan, Rosana, Hong Kong. Peh, Angeline, Birmingham. Chan, Sok-Han, Hong Kong. Penton, Keith, London. Chau, Kwong Lim, Shatin, NT, Hong Kong. Plaxton, George A., Helensburgh. Cheang, Chong Nun, Hong Kong. Pointon, Laurence B., Edgware. Chen Munoz, Cristina, Barcelona, Spain. Pollard, Adrain N., Cheshire. Cheng, Siu Hing, Kowloon, Hong Kong. Redgrove, Claire A., Selsey. Ching, Wai Yai, Shatin, NT, Hong Kong. Richards, Keith, Stoneleigh. Cho, Eun-Gyeong, Seoul, Korea. Richards, Stephen, Eastbourne. Chow, Marianne, Toronto, Ont., Canada. Rigby, Lesley C, Bawtry. Chow, Tze Joak, Kowloon, Hong Kong. Roberts, Amanda, Wirral. Chui, Yiu Wing, Hong Kong. Robinson, Nathan J., Birmingham. Chiu, Fan Chuck, Hong Kong. Rogers, John WS., Stroud. Chudawala, Sucheta, Bombay, India. Sabbagh, Samuel J., London. Chung, Tsz Kin, Kowloon, Hong Kong. Sabbagh, Steven E., Manchester. Clavero Monzon, Alfredo, Barcelona, Spain. Schmidt, Simon R, London. Compte Jornet, Javier, Barcelona, Spain. Scott, Sarah L., Norwich. Crespo Leal, Juan Gines, Barcelona, Spain. Shah, Fatehchand J., London. Cuscp Tortajada, Montserrat, Barcelona, Spain. Share, Stella A., Harrow Weald. Daalmeyeer-Verheyden, Gertruda, Leiden, The Smith, Gerard J., Wargrave. Netherlands, Syn, Lucy, London. de Kok, H., Zandvoort, The Netherlands. Taylor, Victoria A., London. Desai, SuryakantC, Nairobi, Kenya, Tees, Audrey, Glasgow. de Winter, Rene G., Amsterdam, The Netherlands. Thomas-Everard, Lucilla, London. Dikken, Paulien G., Hilversum, The Netherlands. Vannet, Mary A., Dundee. Dimitriadis, Milko M., Rhodes, Greece. Vaughan, Michael, Budleigh Salterton. Dong, Jianhua, Wuchang, China. Vause, Corinne J., Collingham. Dukel, DorindaM., Giessenburg, The Walker, James D., Edinburgh. Netherlands. Waller, Mark S., Bradford. English, Dora Pang, Kowloon, Hong Kong. Webster, Kathleen A., London. Escola Folguera, Montserrat, Barcelona, Spain. Welch, Lizanne, Somerset. Escola Folguera, Teresa, Barcelona, Spain. Wells, Andrew, Caterham. Falk, Carita L., Helsinki, Finland. White, Alison P., York. Farkas, Susan, Vancouver, Canada. Williams, Alison D., Dorking. Felipe De Los, Martin, Barcelona, Spain. Williams, Ruby, London. Fernando, Francis, X., Mt. Lavinia, Sri Lanka. Ferrer Mas, Lucia, Barcelona, Spain. Qualified - Overseas Fontcouberte, Andre L., Paris, France. Abel, Arlan R., Minneapolis, Minn., USA. Foo, Pui Man, Hong Kong. Alvarez-Palacios, Ester, Asturias, Spain. Galloway, Linda L., Kowloon, Hong Kong. Anastassiou, Evagelia, Maroussi, Athens, Greece. Galopim de Carvalho, Rui M., Lisbon, Portugal. Anderson, Ekaterini, Piraeus, Greece. Garcia Roe, Emilia, Barcelona, Spain. Au, Chung King, Hong Kong. Garcia Escrivo, Rosa, Barcelona, Spain. Au, Sze Yin, Hong Kong. Garcia Lopez, Carmen, Barcelona, Spain. Bakayianni-Sa Bou, Aristea, Nikea Piraeus; Greece. Garofalaki, Katerina, Greece. Bernaus Vidorreta, Isabel, Barcelona, Spain. Ginger Sanchez, Ana, Barcelona, Spain. Bevoort-Alwicher, Terrence J., Nymegen, The Gofa, Sophia, Athens, Greece. Netherlands. Goyal, San jay S., Bombay, India. J. Gemm., 1991,22,5 319

Granero Saumell, Angel, Barcelona, Spain. Marti Muntane, Susana, Barcelona, Spain. Hanley, Shaun, Kowloon, Hong Kong. Martinez de los Reyes, Ivorra, Barcelona, Spain. Harmsen, Harmanus P., Bruekelen, The Matsumoto, Naoko, Hong Kong. Netherlands. Mendez Juan, Carolina, Barcelona, Spain. Helppi, Veikko J., Rouaniemi, Finland. Merchant, Azmet F, Bombay, India. Hill, Linda S., Trout Creek, Mont., USA. Meritxell Herrero, Ballbe, Barcelona, Spain. Ho, Chung Keong, Hong Kong. Miller, Carol, Hong Kong. Hogguer, Virginia N., Alphen aid Ryn, The Moix Ribe, Ana, Barcelona, Spain. Netherlands. Molera Reig, Silvia, Barcelona, Spain. Houli, Christiana, Athens, Greece. Montgomery, Richard S., Bangkok, Thailand. Huisman, Philip, Schoonhoven, The Netherlands. Moreno Rastrero, Antonio, Barcelona, Spain. Ichniowski, Jacqueline, Elliott City, Md., USA. Nazareth, Christopher T, Bombay, India. Ip, Ting Cheong, Kowloon, Hong Kong. Ng, Chee Keong, Hong Kong. Jae-Moon, Byun, Seoul, Korea. Ng, Yez King, Kowloon, Hong Kong. Jager, Karin S.M., Oosterhout, The Netherlands. Nickolady, Efthmia, Volos, Greece. Jhareri, Hina Sushil, Bombay, India. Nicolaidis, Nicholas, Harare, Zimbabwe. Jones-Napier, Pennye, Washington DC, USA. Olin, Kauko O., Finland. Kaminara, Meropi, Athens, Greece. Olmedo Bel, David, Barcelona, Spain. Kaminaras, Socrates, Athens, Greece. Oza, Bhagkat M., Bombay, India. Keller, Simone, Luzern, Switzerland. Paatsola, Tapio E., Siilinjaru, Finland. Keung, Chun Wah, Hong Kong. Page, Tayma F, Hong Kong. Khan, Abdul Jabbar, Bombay, India. Paz Tudela, Cristina, Barcelona, Spain. Kiuas, Marja-Sisko, Hameenlinna, Finland. Perera, Bodiyabaduge F, Sri Lanka. Klumpes, Eric, Veere, The Netherlands. Perera, Galhena K., Colombo, Sri Lanka. Ko, Wai Fun, Hong Kong. Perez Barrera, Jose Luis, Barcelona, Spain. Koike, Toshikazu, Tokyo, Japan. Pi Gregorio, Angeles, Barcelona, Spain. Kunnas, Eero D. J., Mikkeli, Finland. Qiao, Min, Hubei Province, China. Kwan, Pik Sim, Kowloon, Hong Kong. Quinton, Sarah E., Virginia Beach, Va., USA. Lakhiani, Roma, Bombay, India. Ramon Mira, Judith, Barcelona, Spain. Lai, Mui Guk Margaret, Hong Kong. Ramon Verdaguer, Montserrat, Barcelona, Spain. Lajara Lopez, Jose, Barcelona, Spain. Ravona, Haim, Hadera, Israel. Lalouska-Koundourou, Radka, Athens, Greece. Riera Siquier, Sebastian, Barcelona, Spain. Lam, Wai Ha, Kowloon, Hong Kong. Roca Tudela, Cristina, Barcelona, Spain. Lau, Lau Yan Wah, Hong Kong. Rohmer, Neva D., Hong Kong. Lau, Mee Sim, Kowloon, Hong Kong. Roukens, Laura K., Gouda, The Netherlands. Lau, Sau Kuen, Kowloon, Hong Kong. Sagrera Llibre, Eduardo, Barcelona, Spain. Lee, Grace Mo Jing, Hong Kong. Salmi, Tarja A., Helsinki, Finland. Leung, Wai Hung, Kowloon, Hong Kong. Sanahuja Ribo, Ramon, Barcelona, Spain. Lee, Wing Mui, Hong Kong. Sarrion Papi, Maria D., Barcelona, Spain. Leung, Hung, Hong Kong. Schell, Martin A., Nanthaburi, Thailand. Leung, Wing Sum, Kowloon, Hong Kong. Schock, John S., Oregon, USA. Ling, Kam Cheong, Kowloon, Hong Kong. Segura Requena, Juan A., Barcelona, Spain. Lo, Hung Kin, Macau, Hong Kong. Sena, Heendeniya V., Ellakkala, Sri Lanka. Lo, Mun Kong, Kowloon, Hong Kong. Shalvi, Judy, Hong Kong. Lohle, Engelina Gemma, Utrecht, The Sidhu, Ran jit K., Limuru, Kenya. Netherlands. Suetani, Hatsuko, Kyoto, Japan. Lozana Alvarez, Luisa, Barcelona, Spain. Tang, Pik Cheung, Hong Kong. Lui, Man Fai, Hong Kong. Tanigawa, Sonoh, Tokyo, Japan. Ma, Chi Yuen, Kowloon, Hong Kong. Temelcoff, Catherine F, Toronto, Ont., Canada. Maas Van Der, Cecile M., Amstelveen, The Torregrosa Guirao, Inocencia, Barcelona, Spain. Netherlands. Tsang, Sui Chang, Hong Kong. Madhvani, Marie L., Nairobi, Kenya. Turpeinen, Jorma J., Helsinki, Finland. Maeda, Katsuya, Hiyogoken, Japan. Vakil, Hetal H., Bombay, India. Maher, Michael A., Kowloon, Hong Kong. Van Der Knaap, Sonja K., Veeve, The Netherlands. Marin i Vivas, Olga, Barcelona, Spain. Van Opstal, Wilma, Tilburg, The Netherlands. Marsh, Leona C, Harare, Zimbabwe. Van Soest, Ingrid A.M., Gouda, The Netherlands. McGregor, Alexandre, Johannesburg, South Africa. Van't Hooft, Jaap, Vught, The Netherlands. 320 J. Gemm., 1991, 22, 5

Veenemans, Vivianne M., Schoonhaven, The Johnston, Paul W, Belfast. 1990 Netherlands. Jones, Colin P, Birmingham. 1990 Vesters, Marco, Schoonhaven, The Netherlands. Jones-Napier, Pennye K., Washington DC, USA. Vila Masana, Ramon, Barcelona, Spain. 1990 Vorasaph, Tracy, Bangkok, Thailand. Jordan, Lynn P, Manchester. 1990 Wenting, Eduard J., Wehl, The Netherlands. Kermorgant-Abily, Claire, Bangkok, Thailand. Wickramaratne, Amugoda T, Hikkaduwa, Sri 1990 Lanka. Kinev, Kathryn A., Atlanta, Ga, USA. 1990 Wong, Leong-Man, Kwun Tong, Hong Kong. Kung, Kwai, Kowloon, Hong Kong. 1990 Wong, Siu Por, Kowloon, Hong Kong. Lai, Sau H.M., Kowloon, Hong Kong. 1990 Xue, Qinfang, Wuchang, Hubei Province, China. Lam, Yick-Man R., Kowloon, Hong Kong. 1990 Yam, Linda Lin-Fong, Shatin, Hong Kong. Lamb, Lois N., London. 1990 Yang, Mingxing, Wuchang, Hubei Province, China. Leong, Kei T.D., Ribeiro, Macau. 1990 Yu, Yim Tonet, Kowloon, Hong Kong. Levy, Aaron N., London. 1990 Yung, Si Yau, Sheung Shui, Hong Kong. Lieftinck, Felice A., Rotterdam, The Netherlands. Zhang, Linxia, Wuchang, Hubei Province, China. 1989 Zho, Xinmin, Wuchang, Hubei Province, China. Lopez Gracia, Anna M.S.I., Barcelona, Spain. 1990 Zhu, Huiyuan, Wuchang, Hubei Province, China. Lui, Kin W.K., Causeway Bay, Hong Kong. 1990 Zugazagoitia Urresti, Aitor, Barcelona, Spain. Ma, Kiu C.K., Kowloon, Hong Kong. 1990 Matthews, Lisa J., Winchester. 1990 MEETINGS OF THE COUNCIL OF Meigh, Melanie J., London. 1990 MANAGEMENT Montgomery, R. Scott, Bangkok, Thailand. 1990 On 26 November 1990 at 21 Greville Street, Mustchin, Vivienne, Auckland, New Zealand. 1990 London EC IN 8SU, a meeting of the Council of McCosh, Samuel M., Birkenhead. 1990 Management was held at which the business trans­ Offord, Philip A., Chandlers Ford. 1990 acted included the election to membership of the Pandya, Neesha, Bombay, India. 1990 following: Parker, Duncan, Toronto, Ont., Canada. 1990 Patterson, Debra A., Toronto, Ont., Canada. 1990 Piatt, Karen K., London. 1990 Fellowship Schell, Martin A., Nonthaburi, Thailand. 1990 Aryatilake, Bamunuarachchige L., Maharagama, Shammas, Siham, Paris, France. 1990 Sri Lanka. 1990 Soung, Min-Hee, Busan, Korea. 1990 Beentjes, Theodorus PC, Uitgeest, The Tan, Min, Shenzhen, China. 1990 Netherlands. 1990 Tock, Graham B., Hull. 1990 Byrne, David M., Birmingham. 1990 Tuovinen, Petri R. J., Kouvola, Finland. 1990 Canty, Gavin, Auckland, New Zealand. 1990 Ueta, Kohei, Kouchi-Ken, Japan. 1990 Carter, Maurice W, Scarborough, Ont., Canada. Van Acker, Alain A. A.M., Tilburg, The 1990 Chow, Marianne, Toronto, Ont., Canada. 1990 Netherlands. 1990 Chu, Sin-Yi C, Kowloon, Hong Kong. 1990 Vartiainen, Risto K., Rovaniemi, Finland. 1990 Cloke, Deborah J., Sevenoaks. 1990 Velthuizen, Irmine H.S., Arnhem, The Cogan, Joanne M., Omaha, NE, USA. 1990 Netherlands. 1990 De Kam, Antje J., Hazerswoude, The Netherlands. Weston, Amy L., Baltimore, Md, USA. 1990 1990 Wong, King S., Kowloon, Hong Kong. 1990 Farrett, Kirsten J., Dover. 1990 Woodham, Sharon, Birmingham. 1990 Farthing, Russell, Colchester. 1990 Wright, Michael J., Watford. 1990 Fung, Wai Y, N.T., Hong Kong. 1990 Wright, Wendy E., Toronto, Ont., Canada. 1990 Gonzalez, Marie C. Y, Hong Kong. 1990 Zoeter, Johannes S., Rotterdam, The Netherlands. Goyal, Sanjay S., Bombay, India. 1990 1990 Hasan, Zia-ul, Toronto, Ont., Canada. 1989 Holen, Yvonne, Utrecht, The Netherlands. 1990 Ordinary Membership Hoogeboom, Paulus N., Hoogland, The Bascombe, Freida, N.T., Hong Kong. Netherlands. 1990 Bassioudis, Vassilis, Thessaloniki, Greece. Huegi, Michael F, Guemligen, Switzerland. 1990 Bertorelli, Andrea E.L., Weston Super Mare. Hui, Fredy WK., Victoria, Australia. 1990 Bessent, Christopher P, Bath. Hui, Wah K., Kowloon, Hong Kong. 1990 Blancardi, Iris, Sospel, France. Hung, Chi L. V., N.T., Hong Kong. 1990 Buncher, Susan, N.T., Hong Kong. Ip, Ting C, Shatin, Hong Kong. 1990 Byun, Jae-Moon, Seoul, Korea. J. Gemm., 1991,22, 5 321

Calhoun, Cathy, Pottstown, Pa, USA. Ibbott, Jane, London. Cor ley, Thomas J., Co Gal way. Kwok, Chi K., Kowloon, Hong Kong. Dodds, Lorraine, Newcastle Upon Tyne. Meza, Samwel P, Glasgow. Durlacher, Noel H.E., London. McFarlane, Neil R., Alloa. Egner, Valerie S., London. Ng, Soon H., London. English, Dora P, Hong Kong. O'Brien, Gillian M., North Berwick. Fernando, Bernard, London. Ogezi, Agbaji E., Jos, Nigeria. Foster, David, Sleaford. Paterson, Lea M.F, Brighton. Galloway, Linda, Hong Kong. Pout, Margaret E., Guildford. Hardeman, Sonia L., Medstead, Nr Alton. Thurlwell, Christopher, Tunbridge Wells. Hirachan, Dev Man, Nara-Ken, Japan. Van Papen, Lorraine, Guildford. Hunter, Charlotte T., Northampton. Walter, Keith, Peebles. Killias, Andree, Houston, Tx, USA. Whelan, Stella A., Morecambe. Kneebone, Garfield D., Penzance. Lakhtaria, Yashwin, London. COVER PICTURE - OCTOBER 1990 ISSUE Leblans, Isabelle, Louvain La Neuve, Belgium. The necklaces (left to right) were fashioned from Macdonald, Dawn, London. the following materials: microcline (amazonstone); Macdougall, Louise J., Watford. lavender jadeite; lapis lazuli; labradorite; nephrite Maeda, Katsuya, Hyogo-Ken, Japan. jade; tiger's-eye; malachite; common opal ('chlor- Nash, Helen E., Slough. opal'); tourmaline; moss agate/cornelian; golden Patel, Pankaj, Wembley. coral (shell rondels); matt quartzes. Pearson, Christopher M., Hayes. Presland, Patrick I., Market Drayton. Ruhmer, Fiona J., London. Shalyi, Judy, Hong Kong. Stergiou, Basil, Bristol. Swift, Tania K.P, London. Letters to the Editor Thomas-Everard, Lucilla D.M., London. Tucker, William J., Douglas. Tzortzopoulos, Theodore, Athens, Greece. From James B. Nelson Watanabe, Tatsuo, Tokyo, Japan. Nelson Gemmological Instruments White, John W, York, Pa, USA. Wu,MeiW, Harlow. Dear Sir, Zafer, Raymond D., Twickenham. In Peter Read's article on 'Reflections on reflec­ On 9 January 1991 at 27 Greville Street, London tivity' (Journal of Gemmology 1990, 22, 97-102), a EC IN 8SU, a meeting of the Council of Manage­ drawing was given of a profile of a hypothetical ment was held at which the business transacted quartz gemstone. included the election to membership of the fol­ The first thing which caught my eye was the lowing: pavilion angle of 45°. Gem faceting practice forbids the use of such a pavilion angle, even for quartz Fellowship stones1. With this angle, I would see internal Aulosalo, Liisa H., Turku, Finland. 1990 reflections of myself in the table, as with a right- Einstoss, Philip M., Toronto, Canada. 1990 angle prism. Elias, Abdul H., London. 1983 A 45° pavilion also implies that any rays entering Jarvis, Kathryn A., Vancouver, Canada. 1990 the stone's table at a zero degree angle of incidence Jones-Brunet, Catherine, Mississauga, Canada. would leave the table exactly parallel to the incident 1990 beam. The drawing showed an emergent angle far Vorasaph, Tracy, Bangkok, Thailand. 1990 from zero. Willmott, Keith R., Colombo, Sri Lanka. 1990 Having been stimulated to learn more about this new strange optical behaviour, the accompanying Ordinary Membership diamond profile was examined. This time I was Antoine, Ian, London. armed with a schoolboys' protractor and a familiar­ Burrow, Denis W, Gravesend. ity with Snell's law. The celebrated Dutchman Day, James PM., Tunbridge Wells. would have been intrigued to see how his physics Diamantopoulos, Moschos, Athens, Greece. have changed since his time. Most things, particu­ Faithfull, John W, Leicester. larly prices, have changed, but even E = mc2 has not Friedland, Melissa, London. risen to E = mc3. 322 J. Gemm., 1991, 22, 5

May I make a plea for authors to have more shaken' by the 'qualitative' nature of this sketch, or compassion for beginners in gemmology who would has felt obliged to reach for his protractor! have to struggle in vain to make sense out of such diagrams which are only qualitatively but not Yours etc., quantitatively correct? Peter G. Read It is always a serious matter if a student's 30 November 1990 confidence has been shaken, but particularly so when moving into a new territory. 68 Forest House, Russell-Cotes Road, Bournemouth, Dorset BH1 3UB. Yours etc., J.B. Nelson From Peter G. Read 15 November 1990 2 McCrone Mews, Belsize Lane, London NW3 Dear Sir, 5BG. With reference to my note on the 'Detection of 1 Harding, B.L., 1975. Faceting limits. Gems & Gemology, XV, 3, 78-88. synthetic emeralds by thermal conductance', which appeared in the October 1990 issue ofThe Journal, I have since been loaned four more synthetic emer­ alds by Alan Hodgkinson. I tested these stones From Peter G. Read under the same constraints as those tested previous­ ly, with the following re suits:- Dear Sir, I am grateful to Jamie Nelson for drawing Average of 5 readings attention to the apparent error in my sketch of the Biron (hydrothermal), 1.04ct 98 profile of a hypothetical quartz gemstone. However, the error in the sketch was confined to an incorrect Lechleitner coated (hydrothermal), 2.26ct 129 labelling of the pavilion angle, and not to the ray Lechleitner 'sandwich' (hydrothermal), 0.68ct 106 path as he assumed. To make the point that the pavilion angle of a Linde crystal (hydrothermal), 3.72ct 84 quartz gem must be increased over that of a brilliant cut diamond (in order to achieve total internal This appears to confirm that the 'solid' hyd­ reflection) I had increased this angle so that this rothermal stones, in common with the previously condition was just achieved for quartz's critical angle tested flux-melt synthetic emeralds, also have a of 40.33 degrees. Unfortunately I then labelled this much greater thermal conductance than the natural angle as 45 instead of 43 degrees, at which latter stone. angle the path for ray 1 in my sketch is substantially During a subsequent telephone call from Nigel correct. I trust that this error has not offended any Israel, who like myself evaluated the original Gem- lapidary reader of The Journal (who in any case tek 'Gemmologist' (a forerunner of the Alpha-test would rarely use the diamond profile for quartz). instrument), I learned that he had found it possible Regarding Nelson's amusing comment on E = to discriminate between peridot and sinhalite using mc2,1 must also confess to have taken some license this instrument. In confirming this, I obtained the with the velocity of light in the diamond sketch in following figures:- that the angles of refraction should have been drawn more realistically to acknowledge diamond's refrac­ Peridot 102 tive index of 2.417 (increasing the in-air angles with respect to the normal for rays 1 and 2 would put this Sinhalite 64 right). In mitigation I would point out that en­ gineering sketches (as opposed to fully dimen­ As the RI and SG of the two stones are similar, sioned drawings) usually bear the legend 'do not and it is not always easy to determine their differing scale', so perhaps I should have taken this precau­ optic signs or discover the additional band in tion and thus avoided the application of Nelson's sinhalite's spectrum, this adds yet another useful protractor! test feature to the Alpha-test instrument. I am indebted to my learned colleague's critical Yours etc., eye, and hope that the offending sketch still con­ Peter G. Read veyed the importance of a gem material's critical angle when determining its pavilion angle, which 7 December 1990 was after all my prime objective. I also hope that no 68 Forest House, Russell-Cotes Road, Bournemouth, student of gemmology has had his 'confidence Dorset BH1 3UB. J.J. Gemm.,Gemm., 1991,22,51991,22,5 323323

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Telephone: 071-404 3334 Fax: 071-404 8843 Volume 22 No. 5. January 1991

1 ^Journal of Gemmology

Contents

Colour as a guide to the composition of scapolite from Burma A.G. Couper 259

'Machingwe': a new emerald deposit in Zimbabwe J. Kanisy C.E.S. Arps and P.C. Zwaan 264

Crystallized and massive rose quartz deposits in Brazil J .P. Cassedanne and M. Roditi 273

Suggestions for photographing jewellery G.V. Foster and N .J. Barker 287

Vulcanite or gutta-percha? That is the question G. Brown 292

Gemmological investigation of a synthetic spinel crystal from the

Soviet Union J.I. Koivula, R.C. Kammerling and E. F ritsch 300

Gemmological Abstracts 305

Book reviews 310

Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 311 Letters to the Editor 321

Copyright© 1991 The Gemmological Association and Gem Testing Laboratory of Great Britain Registered Office: Palladium House, 1-4 Argyll Street, London W1V IAD

ISSN: 0022-1252

Produced by Green Belt Studios: Printed by Quadrant Offset, Hertford, England.