Volume 23 No. 6. April 1993 TheJournal 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 Lawrence Bragg, CH, aBE, MC, B.Sc., FRS Sir Frank Claringbull, Ph.D., F.lnst.P., FGS Vice-Presidents: R K. Mitchell, FGA A.E. Farn, FGA D.G. Kent, FGA Council ofManagement D.}. Callaghan, FGA C.R Cavey, FGA T.}. Davidson, FGA E.A. jobbins, B.Sc., C.Eng., FIMM, FGA I. Thomson, FGA V.P. Watson, FGA, DGA RR Harding, B.Sc., D.Phil., FGA, C. Geol. Members' Council A.}. Allnutt, M.Sc., J. Kessler I. Roberts, FGA Ph.D., FGA G. Monnickendam E.A. Thomson, P. J. E. Daly, B.Sc., FGA L. Music Hon. FGA R Fuller, FGA, DGA }.B. Nelson, Ph.D., FGS, R Velden B. Jackson, FGA F. lnst. P., C.Phys., FGA D. Warren G.H. Jones, B.Sc., Ph.D., P. G. Read, C.Eng., C.H. Winter, FGA, DGA FGA MIEE, MIERE, FGA, H. Levy, M.Sc., BA, FGA DGA Branch Chairmen: Midlands Branch:D.M. Larcher, FBHI, FGA, DGA North-West Branch: I. Knight, FGA, DGA Examiners: A. J. Allnutt, M.Sc., Ph.D., FGA G. H. Jones, B.Sc., Ph.D., FGA L. Bartlett, B.Sc., M.Phil., FGA, DGA D. G. Kent, FGA E. M. Bruton, FGA, DGA R D. Ross, B.Sc., FGA C. R Cavey, FGA P. Sadler, B.Sc., FGS, FGA, DGA S. Coelho, B.Sc., FGA, DGA E. Stern, FGA, DGA A.T. Collins, B.Sc., Ph.D Prof. I.Sunagawa, D.Sc. B. Jackson, FGA C. Woodward, B.Sc., FGA, DGA E. A. Iobbins, B.Sc., C. Eng., FIMM, FGA

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

The GemmologicalAssociation and GemTestingLaboratory ofGreatBritain 27 Greville Street, London EClN 8SU Telephone: 071-404 3334 Fax: 071-404 8843 ^Journal of Gemmology

VOLUME 23 NUMBER SIX APRIL 1993

Cover Picture The Hematita mine in Minas Gérais in 1987 - probably the richest alexandrite concentration ever known. Note the whitish kaolinitic gravel (which carries the gem material) in the foreground, the soil profile in the centre and the valley confluence in the background. (See 'The location, geology, mineralogy and gem deposits of alexandrite, cat's-eye and chrysoberyl in Brazil' pp. 333-54)

ISSN: 0022-1252 F.G.AF.G.A.. youyourr kekeyy ttoo ththee fascinatingfascinating worlworldd ooff GemmologGemmologyy The Gemmological The Gemmological The Gemmological The Gemmological Association and Gem Association's course Association and Gem Associations course Testing Laboratory of has been specially Testing Laboratory of has been specially Great Britain has been compiled into a series Great Britain has been compiled into a series actively involved in of teaching modules actively involved in of teaching modules the very beginning of that are both readable the very beginning of that are both readable Gemmology as an and lavishly Gemmology as an and lavishly independent science. illustrated. independenToday, thet science . illustratedTogether. they AssociationToday, the takes provideTogethe a r they Associatiopride in itsn takes providcomprehensivee a step­ pridinternationale in its comprehensivby-step guide toe stepthe - internationareputation las a learned by-stefascinatingp guid worlde to thofe reputatiosociety ndedicated as a learne to d i fascinatingemmologyg worl andd anof societthe promotiony dedicate dof t o gemmologopportunityy toan earnd an thgemmologicale promotion o f opportunitthe covetedy initialsto earn gemmologicaeducation andl the thFGAe covete - Fellowd initial of thes educatiospread nof an d the FGA-FelloGemmologicalw o f the spreagemmologd of ical The GemmologicaAssociation. l gemmologicaknowledge. l AssociationTo find out. more knowledgeThe Association's. Gemmological Association completeTo find outhet morcoupone covetedThe Association Fellowships is andGemmologica Gem Testingl Associatio Laboratoryn completbelow ande th wee coupowill n covetea markd Fellowshiof excellencep is and Gem Testing Laboratory beloimmediatelyw and w eforward will a onlymar kbestowed of excellenc upone Of Great Britain immediatelthe Associaty ioforwarn's d onlmembers,y bestowe whod upo n Of Great Britain thprospectuse Association givings memberssuccessfu, whlly oundertake the Association's full details of this uniqprospectuue course.s giving successfullwritten andy undertakpractical eDiploma the Association examinations.s full details of this unique course. writte1 -n an--d practica- --l Diplom- a---- examinations-. .------I To GAGTL Education Departmenl, 27 Greville Streel, London ECl N 8SU I Please send details and application form for the Diploma in Gemmology Course. rI To GAGTL Education Department, 27 Greville Street, London ECl N 8SU I Please send details and application form for the Diploma in Gemmology Course. I Name: I I Name: I I Address: I

I Add ress: I I I

I Telephone: GEM; I L ______~ Telephone: . GEM; L: _l 323323 JJ.. Gemm.,Gemm., 1993,1993, 2323,, 6

A methodmethod forfor obtainingobtaining opticoptic figuresfigures fromfrom inclusioninclusionss John l.I. KoivulaKoivula ChiefChief ResearchResearch Gemologist,Gemologist, GemologicaGemologicall InstitutInstitutee ofof AmericAmericaa GeGemm TradTradee LaboratoryLaboratory,, Inc.,Inc., SantaSanta Monica,Monica, California,California, USUSAA

AbstractAbstract A methodmethod forfor obtainingobtaining opticoptic figures fromfrom doublydoubly refractive inclusionsinclusions inin transparenttransparent gemsgems usingusing a a stan­standard dard gemmologicalgemmological microscopmicroscopee iiss introducedintroduced.. SomeSome usefuluseful equipmenequipmentt andand ththee limitationslimitations ooff thithiss techniquetechnique are discussed.

IntroductionIntroduction InIn gemmologygemmology,, non-destructivnon-destructivee testintestingg iiss thethe normnorm.. ThThee vasvastt majoritmajorityy ooff ththee gemsgems encounteredencountered cannot be be examined examined in ina manner a manner that thatis destructive is destruc­ tiveor evenor even potentially potentially destructive destructive to their to their

Fig.Fig. 1.1. TheThe stoneholdcr-conoscopcstoneholder-conoscope mademade byby HaroldHarold OateOatess useusedd toto resolveresolve optiopticc figures from indusionsindusions.. NoteNote ththee sisixx diff'crent­different- sizedsized interchangeableinterchangeable sphericalspherical lenseslenses.. Photograph by RobertRoben FigFig.. 2.2. OneOne axisaxis ofof a biaxiabiaxiall opticoptic figurefigure obtainedobtained bbyy thithiss methodmethod Weldon from aann inclusioninclusion iinn a pinpinkk spinelspinel octahedronoctahedron from StiSri Lanka.Lanka. Photomicrograph by by John John I. I. KoivuJa Koivula appearanceappearance.. ThThee microscopimicroscopicc studystudy ooff inclusionsinclusions playsplays a majomajorr rolrolee iinn non-destructivenon-destructive gemgem identifi­identifi­ cationcation.. InclusionInclusionss exposedexposed aatt ththee surfacesurface durinduringg thethe initialinitial cuttincuttingg processprocess araree ideallyideally suitedsuited forfor detaileddetailed examinationexamination.. HoweverHowever,, itit iiss rarelyrarely possiblpossiblee toto actu­actu­ allallyy grindgrind dowdownn a gegemm toto exposeexpose aann inclusioinclusionn atat thethe surfacesurface foforr X-rayX-ray diffractiodiffractionn oorr chemicalchemical anal­anal­ ysisysis.. YeYett inclusioninclusion recognitionrecognition anandd identificationidentification isis ononee ofof thethe mormoree importantimportant scientificscientific disciplinesdisciplines iinn modermodernn gemmology.gemmology. IInn thithiss arenaarena mosmostt gem­gem- mologistsmologists musmustt workwork 'with'with theitheirr handshands tied'.tied'. AlthougAlthoughh itit iiss veryvery importanimportantt ttoo bebe ableable toto deter­deter­ minemine iiff a gegemm isis naturanaturall oorr synthetic,synthetic, andand treatedtreated oorr untreated,untreated, thithiss mustmust bbee accomplishedaccomplished iinn waysways whichwhich areare nonott harmfuharmfull toto thethe gemgem itself.itself. AAtt ththee retailretail anandd wholesalwholesalee levelevell wherwheree a greatgreat manymany gegemm identificationsidentifications araree donedone,, gemmologistsgemmologists andand appraiserappraiserss dodo notnot havhavee immediateimmediate accessaccess toto testingtesting instrumentsinstruments suchsuch aass X-raX-rayy difI'ractometers,diffractometers, electronelectron microprobemicroprobess anandd RamaRamann laselaserr probes.probes. InclusionInclusion identificatioidentificationn iiss generallygenerally accomplishedaccomplished bbyy meansmeans ofof ththee gemmologicagemmologicall microscope.microscope. CertaiCertainn patternpatternss andand typetypess ooff inclusioninclusionss thathatt havehave beebeenn seenseen beforbeforee areare recognizedrecognized agaiagainn whenwhen theythey araree encounteredencountered.. IInn manymany cases,cases, althoughalthough thethe overalloverall inclusioninclusion scenscenee presentpresentss testimonytestimony thathatt a

© CopyrightCopyright thethe GemmologicalGemmological AssociationAssociation ISSN:ISSN: 0022-12520022-1252 J. Gemm., 1993,23,6 324

gem is natural, individual mineral inclusions apparently colourless, doubly refractive crystal within the scene remain unidentified. If such that measured approximately 1.5 x 1.0 millimetres inclusions are well formed, then their external was used, rather than the calcite-in-ruby described morphology gives evidence of their identity. above. This was done because spinel is isotropic Colour and degree of transparency are also useful and there is no chance of interference from the in this regard. In short, any information that can spinel. Therefore, an optic figure resolved would be gleaned from an inclusion by means of the have to come from the inclusion. microscope is useful in gem identification. First the inclusion in the spinel was examined in With this in mind, it is apparent that polarized polarized light (total extinction) to determine the light would be useful in determining if an inclu­ most appropriate angle for conoscopic examina­ sion is isotropic or anisotropic. In certain cases tion. Then the lens was placed in contact with the perhaps even an inclusion's pleochroism could be spinel immediately above the inclusion (good ascertained. contact was made using a drop of methylene During a polarized light examination of the iodide). After a few moments of manipulation of inclusions in a faceted Burmese ruby, it was the crystal one axis of a biaxial figure with its inter­ noticed that in a certain direction a semi-transpar­ ference rings was noted (Figure 2). This ent inclusion that appeared to be calcite displayed observation immediately eliminated all uniaxial ring-like patterns of bright interference colours. and isotropic minerals as possibilities in the iden­ When a conoscope (consisting of a handle with a tification of this inclusion and yielded information small glass sphere on the end) was placed over the about this crystal that we would not have had oth­ inclusion, in contact with the surface of the ruby, erwise. a partial uniaxial optic figure was observed. In addition to the inclusion in this spinel, and in This may have gone unnoticed because ruby is the ruby previously discussed, a number of other also uniaxial. But it was unusual because the optic known inclusions in transparent gems have also axis direction of the host ruby itself had already been examined by this method. These include been determined and was approximately 40 muscovite in topaz, apatite in spinel and corun­ degrees away from this viewing direction. So it was dum, and biotite in quartz. concluded that the uniaxial figure must have been generated by the inclusion and not by the ruby. Conclusion Immersion in methylene iodide was then used to Although the inclusion in spinel focused on in negate facet interference and a complete uniaxial this paper had no recognizable external shape, its figure was readily seen. However, an attempt at transparency, apparent lack of colour and its photomicrography of the effect, with the available biaxial nature suggested that perhaps it might be equipment, proved to be so awkward as to be albite feldspar. Albite is biaxial and has been pre­ impossible. viously identified by chemical analysis and X-ray means as a comparatively common inclusion in Sri Method Lankan spinels (Gübelin and Koivula, 1986). This observation and the problem with pho­ This technique of obtaining optic figures from tomicrography were discussed with gemmologist inclusions will not work in many cases. There are Harold A. Oates of Glen Ellyn, Illinois, USA. certain limitations that should be noted. First of Being a machinist as well as a gemmologist, Mr all the host gem must be transparent, as should Oates manufactured a special stoneholder-con- the inclusion (although some limited success has densing lens combination that secured both the been had with semi-transparent gems and inclu­ gem and lens, making photomicrography of the sions). The external morphology of the crystal or effect possible. cut gem must not be so complex as to interfere The device, pictured in Figure 1, consists of a with the spherical condensing lenses' ability to stoneholder with a flexible arm piggy-backed resolve an optic figure (total immersion in a prop­ above it. The flexible arm can hold any one of six erly selected liquid will help in such cases). The strain-free glass sphere-lenses. To conform to a inclusion cannot be too deep within the host. The wide range of gem and inclusion sizes, the spheri­ nearer to the surface the better. All of the inclu­ cal lenses themselves are of variable size (from 1 sions successfully examined by this method so far to 6 millimetres in diameter). When total immer­ have been within 2 millimetres of the surface of sion is not being used, a small droplet of suitable their hosts. The inclusion's orientation in the host immersion oil is placed between the lens and the material must be such that its optic axis (or one of gem to facilitate good optical contact. its optic axes in the case of biaxial materials) can For illustration of this technique, a natural pink be lined up by the spherical condensing lens. The Sri Lankan spinel crystal containing a transparent, inclusion must also have some size to it (lxl mil- J. Gemm., 1993, 23, 6 325

limetre or larger is suggested). The smaller the a gem and noticed an optic figure from an inclu­ inclusion the more difficult it is to work with. In sion they might erroneously think that the optic doubly refractive host materials the optic axis of figure they were observing was a property of the the inclusion must be sufficiently off-orientation host material itself, and a mistake in identification from the optic axis of the host in order to avoid could result. While this possibility is remote, it is interference. Partial optic figures must be inter­ nonetheless possible. This is in fact the way that preted with caution. It should also be noted that the author discovered this effect, i.e. by accident. this method can be very time consuming in many cases, although it is an excellent exercise for Reference increasing microscopic skill. Gübelin, E.J., Koivula, J.I., 1986. Photoatlas of One final thought concerns the possible acci­ inclusions in gemstones. ABC Edition, Zürich, Switzerland. dental discovery of this effect by a student of gemmology. If perhaps a student were examining [Manuscript recieved 28 October 1992]

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Gemmological Association and Gem Testing Laboratory of Great Britain 27 GREVILLE STREET (SAFFRON HILL ENTRANCE) LONDON, EC 1N 8SU A • TELPHONE: 071 404 3334 FAX: 071 404 8843 • 326326 J.J. Gemm.,Gemm., 1993,1993, 23,23, 66

FreshwaterFreshwater pearlpearl cultivationcultivation inin VietnamVietnam (1) (2) (3) 4(4) G. BossharfIBosshart ),, H. HoHo(2),, E.AE.A.JobbinP. Jobbins ) and K. ScarradScarratt )

((1' )G) Gübeliiibelinn GemmologicalGemmological Laboratory, Lucerne,Lucerne, SwitzerlandSwitzerland (2) ( 2 ) AsianAsian InstituteInstitute ofof GemologicalGemological SciencesSciences,, Bangkok, ThailandThailand (33 l) ( GemmologicalGemmological AssociationAssociation andand GemGem TestingTesting LaboratorLaboratoryy,, London,, EnglandEngland (44 l) ( GIAGIA GemGem TradeTrade LaboratLaboratoryory,, NewNew York,York, USAUSA

FigFig.. 1I.. StreeStreett scenscenee inin Hanoi.Hanoi. AbstracAbstractt severaseverall sourcesourcess thathatt thertheree wawass somsomee productioproductionn ooff DurinDuringg a visivisitt ttoo HanoiHanoi,, ththee capitacapitall citcityy ooff VietnamVietnam,, 'pearls''pearls:, botbothh naturanaturall anandd culturedcultured,, withinwithin,, anandd iinn ththee authorauthorss becambecamee awarawaree ofof a freshwaterfreshwater pearlpearl culturingculturing ththee waterwaterss surroundingsurrounding,, VietnamVietnam.. A furthefurtherr opporoppor­­ operatiooperationn oonn HHoo TayTay,, a lakelake situatedsituated inin thethe north-westnorth-west ofof tunittunityy ttoo enteenterr VietnamVietnam,, principallprincipallyy ttoo updatupdatee ththee ththee capitalcapital.. WhilsWhilstt ththee industrindustryy iiss stilstilll youngyoung,, iitt iiss situatiosituationn iinn ththee LuLucc YeYenn anandd QuQuyy ChaChauu rubrubyy self-sufficientself-sufficient,, anandd furthefurtherr farmfarmss araree planneplannedd ttoo comcomee depositsdeposits,, arosarosee foforr ththee authorauthorss iinn earlearlyy JanuarJanuaryy into operation in the near future. into operation in the near future. 1993.. PrioPriorr toto,, anandd iinn betweebetweenn ththee visitvisitss ttoo ththee LuLucc The Ho Tay farm utilizes the wild mussels found in The Ho Tay farm utilizes the wild mussels found in Yen and Quy Chau districts the authors stayed in an ththee laklakee anandd mother-of-pearmother-of-pearll beabeadd nuclenucleii cucutt frofromm aa Yen and Quy Chau districts the authors stayed in an speciespeciess ooff Unio foundfound inin thethe northernnorthern riversrivers ofof VietnamVietnam.. hotehotell oonn Hanoi'Hanoi'ss WesWestt LakLakee (H(Hoo Tay)Tay).. WhilsWhilstt therethere,, PearPearll colourcolourss araree naturanaturall anandd areare,, pinkpink,, orangeorange,, brownbrown,, thetheyy madmadee enquirieenquiriess abouaboutt pearpearll productioproductionn iinn whitewhite,, lighlightt greygrey,, anandd blackblack.. generalgeneral,, anandd werweree surprisesurprisedd ttoo learlearnn ooff aa freshwaterfreshwater culturinculturingg farfarmm leslesss thathann aa kilometrkilometree awayaway.. IntroductioIntroductionn IItt mamayy bbee difficuldifficultt ttoo understanunderstandd hohoww oorr whwhyy iitt iiss DurinDuringg ththee authorsauthors'' visitvisitss ttoo south-eassouth-eastt AsiAsiaa iinn possiblpossiblee foforr aa pearpearll farfarmm ttoo exisexistt iinn ththee centrcentree ooff aa ththee lattelatterr threthreee monthmonthss ooff 19921992,, wwee hearheardd frofromm citcityy witwithh aa populatiopopulationn ooff thre threee millionmillion.. HoweverHowever,, aass

CC CopyrighCopyriabtt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-1250022-12522 JJ.. Gemm.Genun.,, 19931993,, 2323,, 6 327

Fig.. 2.. SectioSectionn ooff HanoHanoii citcityy mamapp showinshowingg ththee locatiolocationn ooff ththee HHoo TaTayy pearpearll farfarmm (shown(shown ,o 5, bbyy ththee 'flower'flower'' symbol)) oonn mi l es ththee eastereasternn bankbankss ooff ththee miles WesWestt LakeLake..

isis clearlyclearly evidentevident fromfrom FigureFigure 1,1, therethere isis relativelyrelatively thethe HaHa LongLong baybay oror inin thethe FaiFai TsiTsi LongLong archipelagoarchipelago Iilittl tdee useuse ofof thethe motormotor car,car ,and and wi wit thh the the bicycle bicycle being being offoff thethe north-easternnorth-eastern coastcoast ofof Vietnam.Vietnam. ItIt wawass thethe predominantpredominant modemode ofof transport,transport, notnot onlyonly thethe furtherfurther indicatedindicated thatthat therethere waswas somesome involvementinvolvement country,country, butbut alsoalso thethe capitalcapital city,city, isis stillstill largelylargely byby a JapaneseJapanese firm,firm, althoughalthough inin whatwhat capacitycapacity waswas unaffectedunaffected byby environmentalenvironmental pollution.pollution. notnot mademade clear. OtherOther enquiriesenquiries confirmedconfirmed thethe possibilitypossibility ooff orangeorange conchconch (type)(type) pearlspearls (Scarran,(Scarratt, 1992)1992) beingbeing FreshwaterFreshwater pearlpearl culturingculturing in in Hanoi Hanoi foundfound offoff shore,shore, asas wellwell asas saltwatersaltwater culturing.culturing. EnquiriesEnquiries aboutabout freshwaterfreshwater pearlpearl farmingfarming re­re­ DetailsDetails concerningconcerning thethe saltwatersaltwater culturingculturing werewere vealedvealed a youngyoung butbut blossomingblossoming industry. industry .Apart Apart from from difficultdifficult toto obtain,obtain, andand timetime constraintsconstraints preventedprevented smallsmall operationsoperations inin a numbernumber ofof (unidentified)(unidentified) thethe authorsauthors fromfrom visitingvisiting thethe locality.locality. However,However, thethe VietnameseVietnamese lakes,lakes, twotwo operationsoperations werewere mentionedmentioned informationinformation gainedgained pointedpointed toto oneone culturingculturing centrecentre inin particular:particular: thesethese werewere inin thethe estuaryestuary ofof thethe RedRed easteast ofof thethe portport citycity ofof Haiphong,Haiphong, locatedlocated eithereither inin RiverRiver (Song(Song Hong)Hong) andand a stationstation inin HanoiHanoi citycity itselfitself 328 J. Gemm., 1993, 23, 6

Fig. 3. Snail harvesting in Ho Tay Lake.

Fig. 4. View across Hanoi's West Lake with the fenced-in rafts of the Ho Tay pearl farm, as seen from the main building of the I Tay Fish Development and Investment Company. J. Gemm., 1993, 23, 6 329

on Ho Tay. shell of a Unio species found in rivers of the At very short notice the authors were granted a northern provinces. The shape of the nuclei varies visit to the facilities of the Ho Tay Fish Develop­ from nearly spherical to elliptical or button-shaped, ment and Investment Company (the company their hue is white, cream or light orange, and the responsible for the development of pearl culturing diameters range from roughly 3 to 5mm. The on Ho Tay) which are located on the banks of the non-spherical shapes were stated to be desirable for lake (Figure 2). This lake is situated in the north­ the creation of natural-looking end products and west of the capital and is isolated from the Red River the bead colours were said to be unaltered. by a high-water protection dam. The water quality The living molluscs employed for pearl culturing of the lake is apparently good since pearls appear to are of the Cristaria plicata species (Figure 5), be farmed successfully and fishing and snail har­ reported by Jobbins & Scarratt (1990), to be used vesting can be observed daily (Figure 3). also in Chinese farms. Some authors have placed this species in the Anodonta genus, but this is Development and production of the Ho Tay rejected by others who retain Cristaria. The supply enterprises of new molluscs is provided by collecting native The Ho Tay Fish Development and Investment animals from the Ho Tay. Spatting has not been Company, formerly solely occupied with fishing used to date. The shells roughly measure 150xll0x and fish breeding, began feasibility studies on pearl 20mm at the time of harvest and most exhibit an farming in 1986, consulting Japanese experts on the elegantly greyish-purple mother-of-pearl interior matter. Mr Vu Dang Khoa, director of the company, and large, lobular orange-brown areas of variable revealed to the authors that by 1989 these studies size. were completed. Epithelium strips are cut from the mantle tissue Actual production began in 1990 when 500 pearls of sacrificed Cristaria animals, fashioned into were produced. In 1991, 1000 pearls were har­ squares of approximately 3 x 3mm and dipped in an vested, followed by 3000 in 1992. It is hoped to orange antibiotic liquid to prevent infection of the produce 8000 pearls in 1993. The cultured pearls molluscs to be operated on. Subsequently, six to have only been exported to Asian countries to date. eight short cuts are placed in the epithelium of the The operation witnessed by the authors is run by a mantle tissue (3 to 4 on each side) of the living small crew. The mollusc processing team consists of bivalves and a corresponding number of beads two individuals. The plant has several office build­ inserted. To initiate nacre growth around the beads, ings as well as a fenced-in farm containing an the epithelium squares are placed on top of the anchored bamboo raft of about 15 by 10 metres already inserted nuclei. floating approximately 15 metres off the lakeshore (Figure 4). In each of the round wire baskets, Success rates/Production time suspended to a water depth of less than two metres The success rate at present is three nucleated, from the raft, are about ten bivalves. nacre-coated pearls out of six to eight beads per implanted mollusc. Whilst this may appear modest The Ho Tay freshwater culturing technique the rejection of an inserted bead normally results in The standard technique of the Ho Tay enterprise the production of a non-nucleated cultured pearl utilizes fashioned mother-of-pearl beads from from the tissue implant placed with the bead. The freshwater shells. The use of beads in freshwater growth period of 18 to 24 months is long in culturing is not a new technique, indeed examples comparison with the 9 months needed for non- are known as far back as 1761, but in modern times nucleated pearls in Chinese waters but short com­ (post World War II) it has not been the accepted pared to the reported Lake Biwa conditions (up to practice, ie., in the mass market product cultured in 36 months for the first harvest). No indications were China. However, recent years have seen an increase made regarding re-use of the Cristaria clams for a in the use of this technique - beading appears to be second crop (Hyriopsis schlegeli, for example, con­ applied today in some North-American and certain tinue to produce pearls when returned to the waters larger Chinese freshwater cultured pearls using of Lake Biwa, not requiring implantation of new Japanese-made nuclei (Man Sang, 1992). The beads tissue material, Muller-port, 1981). Nacre thick­ used for culturing in China are often dyed and their ness, also being a measure of success, is discussed dark colour is visible through the mostly thin below. nacreous coating - compare Japanese saltwater cultured pearls of low quality (Hänni, 1993). The Ho Tay cultured pearls and their properties The Ho Tay bead material used for insertion is Three lots of cultured pearls were shown to the locally cut out of the small (dimensions approx­ authors for examination. The assemblage of these imately 80 x 45 x 15mm), but comparatively thick fourteen pearls looked so varied and pleasing that it 330 J. Gemm., 1993, 23, 6 was deemed worth a more detailed description. The considered unacceptable by standards developed specimens were supplemented by the addition of for the grading of cultured pearls by the Gem one yellow-banded white specimen to the top Testing Laboratory in London and the CISGEM right-hand row (no.4 in Figure 6). Laboratory in Milan. The nacre coat of pearl no.4, The nearly spherical shape of the largest pearl of however, has an acceptable minimum thickness of the batch (no. 1, upper left) is in contrast to the more about 0.65mm. familiar shapes associated with tissue-graft freshwa­ Depending upon the structure differences of the ter cultured pearls from other sources. tested pearls, there is a wide range of densities. The Typically the latter are 'semi-round' (roundish) to spherical Unio bead pictured in the lower right baroque. In fact, as can be seen from the radiograph corner of Figures 6 and 7 gave a hydrostatically of the fifteen undrilled pearls, only two are bead- determined value of 2.80g/cm3. The bead-nucleated nucleated (again no. 1 on the top left in Figure 7 and pearls no.l (2.56 ct) and no.4 (2.05 ct) showed no.4. All others are tissue-grafted or non-nucleated densities of 2.78 and 2.65g/cm3 respectively. These cultured pearls*. The fifteen pearls exhibit a lower values can be explained by the thin nacre coat mostly smooth surface, good lustre and a fair to of the first and a void on one side of the bead inside good orient. the second pearl.

Fig. 5. Cristaria plicata shell with two encapsulated nuclei displaying the colour of the underlying shell (orangy pigment on the left and pinkish pigment on the right) together with the pearl batch examined. The bead-nucleated pearls grow in 5 to 7mm The densities of the non-nucleated pearls ranged sizes, with rare maximum diameters up to 12mm. from 2.71 to 2.53g/cm3. In this group, pearls nos. 6, The non-beaded pearls are generally smaller. The 2 and 12 are the most dense (in this sequence). The weight range of the pearl sample examined is from two lowest figures, 2.62 and 2.53g/cm , are caused 2.56 ct (no.l) to 0.51 ct (no.6). by the biggest cavities per volume visible in pearls Pearl no. 1 shows a nacre thickness of approx­ no. 10 and no. 15. There is a definite relationship imately 0.1 to 0.3mm, the lower figure being between the size of the central void or tissue remainder and the pearl density: the more compact * The terms 'non-nucleated'and 'tissue grafted' have the same meaning and the pearl, the higher density value, as subsequently reter to the same type of eultured pearl. The term 'keshi' is not used in the confirmed by the internal structures displayed in text, but it should be made clear that it does not apply to the non-nucleated or tissue-graft pearls referred to in the text above. the X-radiograph (Figure 7). J. Gemm., 1993, 23, 6 331

Fig. 6. The fifteen freshwater cultured pearls examined from Fig. 7. X-radiograph of the fifteen Ho Tay cultured pearls and the West Lake (Ho Tay) in Hanoi, Vietnam, lined up one bead, arranged as in Figure 6. Numbering in rows according to colour types (orange, white, pink, fancy). from top left, pearls nos. 1 and 4 are nucleated, all Identical arrangement as in Figure 7 for direct com­ others are tissue-grafted or contain a void. parison, with one spherical Unio mother-of-pearl bead in the lower right corner.

The colour of Ho Tay cultured pearls orange 500 > 440nm As in most gem materials, colour is the outstand­ pink 440 > 550nm ing property of the pearls examined. These come in purplish-pink 440 = 550nm a considerable range of hues, pure orange being the white 440 > 680nm most unusual one. Ho Tay pearl colours were reported to be mostly pink, orange, brown and more Mixed colours show the listed absorption bands occasionally white, light grey and almost black. roughly in the ratio of their contributing hues. It is This is in contrast with the three lots shown, white known that the organic colouring components and pink being the predominant hues. (porphyrine and conchiolin) of the mantle tissue as The present colours were measured in the reflect­ well as the aragonite platelet thickness (0.9mm in ance mode of the Zeiss MCS 311 Multi-channel Chinese Cristaria, Gutmannsbauer, 1992) influence Spectrometer. This technique has been applied for the pearl colours but the exact causes need further many years, especially in Japan (Komatsu, 1991), study. for the separation of natural black cultured pearls No evidence was found to indicate other than from those dyed black with silver nitrate, ie., natural colours for the examined undrilled Ho Tay 'black-lip absorption' versus dyestuff absorption. pearls. This confirms the official claim that the Though only a preliminary colorimetric study of pearls were not enhanced (i.e. not dyed, heated or the Ho Tay and other known freshwater cultured irradiated). However, white and black being the pearls was conducted, it became evident that there preferred colours, Hanoi sources state that dying is a positive correlation between the following hues has been tested for application to off-coloured and approximate absorption band positions: cultured pearls. 332332 JJ.. Gemm.Gemm.,, 1993,1993, 23,23, 6

OutlookOutlook AcknowledgementAcknowledgementss VietnamVietnam hashas ththee potentiapotentiall ttoo becombecomee aann impor­impor­ GratefuGratefull thanksthanks areare extendeextendedd toto MrMr NguyeNguyenn DinhDinh tantantt sourcesource ooff freshwaterfreshwater cultureculturedd pearlspearls.. ItIt hashas MinhMinh TriTri,, GeneraGenerall DirectorDirector ooff ththee Viet-ThaiViet-Thai GemsGems beebeenn pointepointedd outout thatthat thertheree areare atat leasleastt threethree CompanCompanyy anandd hihiss collaborators,collaborators, anandd ttoo MMrr VVuu DangDang operationoperationss inin variouvariouss lakeslakes,, thethe waterwaterss ooff whicwhichh areare KhoaKhoa,, DirectoDirectorr ofof ththee HoHo TaTayy FisFishh DevelopmentDevelopment stillstill largelylargely unaffecteunaffectedd bbyy pollutionpollution problems,problems, mostmost anandd InvestmenInvestmentt CompanCompanyy andand hihiss teateamm foforr provid­provid­ likelylikely becausbecausee agricultureagriculture predominatepredominatess overover indus­indus­ iningg introductionintroduction,, translationtranslation,, accessaccess ttoo andand demon­demon­ trytry iinn allall bubutt a fefeww urbanurban areas.areas. strationstration atat thethe pearpearll farm.farm. MissMiss NicolNicolee Surdez,Surdez, ThThee HHoo TaTayy FisFishh DevelopmentDevelopment andand InvestmentInvestment seniorsenior stafstafff gemmologisgemmologistt aatt thethe GübeliGiibelinn Gemmolo­Gemmolo- CompanyCompany planplanss forfor ththee HHoo TayTay stationstation toto becomebecome gicalgical LaboratoryLaboratory,, Lucerne,Lucerne, provideprovidedd densitdensityy datadata ooff ththee largeslargestt suchsuch operatiooperationn iinn VietnaVietnamm iinn 19931993.. ththee cultureculturedd pearls.pearls. ThreeThree additionaladditional farmfarmss wilwilll gogo intintoo productioproductionn thisthis ThreThreee ooff ththee authorauthorss alsalsoo wiswishh ttoo extendextend specialspecial yearyear;; oneone inin Hanoi,Hanoi, ononee iinn HaHa NaNamm NinNinhh ProvinceProvince thankthankss toto theitheirr co-author,co-author, MMrr HenryHenry Ho,Ho, forfor anandd anotheanotherr inin HaHaii HunHungg Province,Province, thethe latterlatter twotwo arrangingarranging ththee variousvarious VietnaVietnamm expeditionsexpeditions,, ttoo R.c.R.C. areare bothboth iinn ththee RedRed RiverRiver deltadelta.. WitWithh increasingincreasing KammerlingKammerling forfor helpfuhelpfull adviceadvice andand NicNickk DelreDelre forfor outputoutput figures,figures, thethe VietnameseVietnamese freshwaterfreshwater pearlspearls artworartworkk andand photography.photography. maymay becombecomee aann importantimportant additioadditionn toto ththee ChineseChinese productproductss inin thethe futurefuture,, especiallyespecially iiff theythey areare growngrown ReferenceReferencess witwithh thickerthicker thathann normalnormal nacre,nacre, asas evidenceevidencedd byby Gutmannsbauer,Gutmannsbauer, W.w.,, 1992.1992. Morphologische,Morphologische, strukturellestrukturelle undund thosethose examineexaminedd bbyy ththee authors.authors. chemischchemise hee UntersuchungenaUntersuchungenann PerlmutterPerlmutter undund PerlePerlenn einigereiniger ToTo encounterencounter a pearlpearl farmfarm inin a majormajor metropolitanmetropolitan perlenbildenderperlenbildender Muscheln.Muscheln. Univ.Univ. BaselBasel,, diplomadiploma thesis.thesis. HänniHanni,, H.,H., 1993,1993, personapersonall communication.communication. areareaa waswas a greagreatt surprise.surprise. Pearls,Pearls, notnot onlonlyy fromfrom JapaJapann PearlPearl PromotionPromotion Society:Society: Shapes of (freshwater) Pearls,Pearls, freshwatefreshwaterr molluscsmolluscs,, appeaappearr toto bebe symptomaticsymptomatic ooff undateundatedd chart.chart. thethe specialitiesspecialities andand treasuretreasuress thatthat VietnaVietnamm holdsholds inin KomatsuKomatsu,, H.H.,, 1991,1991, personapersonall communication.communication. storestore forfor ththee worlworldd market.market. ConcConchh pearpearll fishing inin MaMann SangSang JewelryJewelry Co.Co. Ltd.Ltd.,, 1992,1992, salesaless brochurebrochure,, HonHongg Kong.Kong. Muller-PortMuller-Port,, A.W., 1981.1981. SüsswasserperlenSusswasserperlen (Biwa Freshwater VietnamesVietnamesee coastacoastall waters,waters, forfor instanceinstance,, hahass existedexisted pearls), KobeKobe,, Japan.Japan. forfor a lonlongg period,period, butbut isis stillstill notnot widelywidely known.known. JobbinsJobbins,, E.A.E.A.,, Scarratt,Scarratt, K.K.,, 1990.1990. SomeSome aspectaspectss ooff pearlpearl Flame-structured,Flame-structured, naturanaturall conch-typconch-typee pearlpearlss ooff production with with particular particular reference reference to cultivation to cultivation at Yang-xin, at Yang­ nearlynearly purpuree orangeorange colourcolour andand sizessizes uupp ttoo overover 200200 ctct xin, China.].China. J. Gemm., 2222,, I,1, 3-IS.3-15. RepettoRepetto,, S.,S., 1992,1992, 1993,1993, personapersonall communications.communications. havhavee comcomee fromfrom PhuPhu QuoQuocc IslandIsland neanearr ththee Cambo­Cambo­ Scarratt, K., K., 1992. 1992. Notes Notes from from the Laboratory-15.the Laboratory-IS.]. J. Gemm., Gemm., diandian bordeborderr (Repetto,(Repetto, 1992,1992,1993 1993)) andand competecompete withwith 23,3,131-9.23, 3, 131-9. thosthosee fromfrom ThaiThai anandd BurmeseBurmese waters.waters. J.J. Gemm.,Gemm., 1993,1993, 23,23, 6 333333

TheThe location,location, geology,geology, mineralogymineralogy andand gemgem depositsdeposits ofof alexandrite,alexandrite, cat's-eyecat's-eye andand chrysoberylchrysoberyl inin BrazilBrazil Jacques Cassedanne, Cassedanne, D.Sc.,* D.Sc.,* and and Maurice Maurice Roditi, Roditi, FGA** FGA**

*Institute*Institute ofof GeosciencesGeosciences UFRJ-CNPq,UFRJ-CNPq, CidadeCidade Universitaria,Universitária, IlhaIlha dodo Fundiio,Fundão, 21,910,21,910, RioRio dede Janeiro,Janeiro, BrazilBrazil **Maurice**Maurice RoditiRoditi Jewellers,Jewellers, RuaRua ViscondeVisconde dede Piraja,Pirajá, 482,482, Ipanema,Ipanema, 22,410,22,410, RioRio dede Janeiro,Janeiro, BrazilBrazil

AbstractAbstract distinguished:distinguished: Alexandrite,Alexandrite, cat's-eyecat's-eye andand transparenttransparent chrysoberylchrysoberyl areare - chrysoberyl,chrysoberyl, goldengolden yellowyellow (known(known asas 'crisolita''crisolita' inin thethe gemgem chrysoberylchrysoberyl varietiesvarieties soughtsought afterafter inin Brazil.Brazil. Brazil).Brazil). ItIt shouldshould notnot bebe mistakenmistaken forfor peridot,peridot, whosewhose PrimaryPrimary chrysoberylchrysoberyl depositsdeposits areare a fewfew differentiateddifferentiated locallocal namename isis thethe samesame thinthin graniticgranitic pegmatitespegmatites emplacedemplaced inin granite,granite, gneissgneiss andand - cat's-eyecat's-eye oror cymophanecymophane withwith chatoyancychatoyancy ofof a mica-schists, presently presently abandoned, abandoned, and and granitic granitic pegma­ pegmatitesbrightbrigh t lineline inin thethe translucenttranslucent stonesstones cutcut enen cabochoncabochon tites cuttingcutting maficmafic and/orand/or ultra-maficultra-mafic rocks.rocks. InIn ththee laslastt - alexandrite,alexandrite, greenish-bluegreenish-blue inin colourcolour inin daylightdaylight case,case, a fewfew alexandritesalexandrites areare associatedassociated withwith emeraldsemeralds whichwhich areare foundfound nearnear thethe contactcontact pegmatite/walpegmatite/walll rockrock andand turningturning redred inin incandescenincandescentt light.light. (Bahia(Bahia andand MinasMinas GeraisGerais States).States). CurrentlyCurrently workedworked LargLargee facetefacetedd gemsgems andand cabochonscabochons cancan bebe mademade chrysoberylchrysoberyl depositsdeposits areare detritaldetrital:: eluvial,eluvial, highhigh andand loloww fromfrom chrysoberylchrysoberyl andand cat's-eyecat's-eye andand samplessamples ofof colluviacolluviall terracesterraces andand alluvialalluvial,, thethe latterlatter beingbeing thethe mosmostt severalseveral tenstens ofof caratscarats inin weightweight areare known.known. OnOn thethe important.important. TheseThese depositsdeposits areare locatedlocated inin thethe MinasMinas otherother hand,hand, alexandritealexandrite alwaysalways producesproduces smallersmaller cutcut Gerais,Gerais, BahiaBahia andand EspiritoEspirito SantoSanto States;States; thethe biggestbiggest gems.gems. prospectprospectss are:are: CorregoCórrego dodo Fogo,Fogo, CorregoCórrego dada FaiscaFaisca andand ChrysoberylChrysoberyl essentiallyessentially occursoccurs inin thethe graniticgranitic HematitaHematita inin thethe StateState ofof MinaMinass GeraisGerais andand CorregoCórrego suite,suite, thatthat isis toto say:say: pegmatitespegmatites andand aplites.aplites. ItIt Alegre in the State of Espirito Santo. A detailed Alegre in the State of Espirito Santo. A detailed sometimessometimes occursoccurs iinn micamica schistsschists and,and, rarely,rarely, inin formationformation descriptiondescription isis providedprovided forfor eacheach depositdeposit typetype,, andand thethe heavyheavy mineralmineralss associatedassociated withwith chrysoberylchrysoberyl iinn dolomiticdolomitic oror calciccalcic skarns.skarns. ChrysoberylChrysoberyl depositsdeposits ththee finfinee gravegravell fractiofractionn araree listedlisted.. AssociateAssociatedd witwithh belongbelong ttoo pegmatiticpegmatitic,, pneumatolytic-hydrothermalpneumatolytic-hydrothermal chrysoberychrysoberyll iinn ththee coarscoarsee gravegravell fractionfractionss areare:: amethystamethyst,, anandd hydrothermahydrothermall typetypess (Smirnov(Smirnov,, 1977)1977).. aquamarineaquamarine,, garnetgarnet,, smokysmoky quartzquartz,, topaztopaz,, tourmalinetourmaline IInn BrazilBrazil,, chrysoberychrysoberyll iiss prospecteprospectedd foforr iinn thethe and, inin lesserlesser amount:amount: andalusite,andalusite, roserose quartz,quartz, moonstone, moon­ StateStates s ooff MinaMinass GéraisGerais,, BahiBahiaa anandd EspiritEspiritoo SantoSanto stone, rutilerutile,, sapphirsapphiree anandd zirconzircon.. LocallLocallyy chrysoberylchrysoberyl andand,, nowadaysnowadays,, onlonlyy iinn detritadetritall depositsdeposits.. TheseThese iiss a by-producby-productt ooff ththee alluviaalluviall workinworkingg ooff otheotherr gemgemss resulresultt frofromm ththee partiapartiall oorr totatotall destructiodestructionn ooff such as diamond,diamond, aquamarineaquamarine or or andalusite. andalusite. primarprimaryy depositdepositss whicwhichh araree granitigraniticc pegmatites,pegmatites, TwTwoo mapmapss (Figure(Figuress 1I andand 2)2 )show show thethe locations locations ofof the the localllocallyy intrudeintrudedd intintoo ultramafiultramaficc rocksrocks.. OuOurr purpose,purpose, chrysoberychrysoberyll depositsdeposits,_, aann idealizeidealizedd diagradiagramm illustrateillustratess ththee typetypess ooff deposidepositt (Figur(Figuree 77)) anandd sectionsectionss araree shownshown ofof thereforetherefore,, iiss ttoo describdescribee ththee variouvariouss typetypess ooff chry­chry­ a seriesseries ofof alluvialalluvial depositsdeposits (Figure(Figure 8)8).. soberylsoberyl depositdepositss (cat's-ey(cat's-eyee anandd alexandritalexandritee varietiesvarieties AlAlll chrysoberychrysoberyll prospectprospectss araree rudimentarilrudimentarilyy workedworked,, beinbeingg specifiedspecified aass appropriate)appropriate),, theitheirr locationlocation,, thethe bbyy meanmeanss ooff hanhandd dudugg smallsmall pitpitss oorr irregulairregularr opeopenn pitspits,, associateassociatedd mineralmineralss anandd ththee produceproducedd gemsgems,, todaytoday anandd sometimesometimess bbyy meanmeanss ooff a gravegravell pumpumpp (dredge)(dredge).. oorr iinn ththee past.past. PhysicaPhysicall propertiepropertiess anandd gemmologicagemmologicall characteristiccharacteristicss ooff BraziliaBraziliann gegemm chrysoberychrysoberyll araree reportedreported,, aass araree ththee PegmatitPegmatitee depositsdeposits significansignificantt inclusionsinclusions.. Granite pegmatites without without ultramafic ultramafic rocks rocks association association IntroductioIntroductionn FeFeww depositdepositss araree accessiblaccessiblee foforr researcresearchh anandd aatt ththee ChrysoberyChrysoberyll (BeAl(BeAI220044)) holdholdss a first clasclasss positiopositionn presenpresentt timtimee nonnonee araree workedworked.. DepositDepositss mineminedd iinn betweebetweenn ththee rarerarerr anandd highehigherr pricepricedd BraziliaBraziliann gemsgems.. ththee paspastt werweree fefeww iinn numbenumberr anandd frequentlfrequentlyy cavecavedd OwinOwingg ttoo a hardneshardnesss ooff 8. 55 anandd aann averagaveragee densitdensityy ooff inin.. RecordRecordss ooff thethemm araree keptkept,, statstatee bbyy statstatee (se(seee ththee 33 3.75g/cm ,, iitt occuroccurss aass prismatiprismaticc oorr platyplaty,, single oorr locatiolocationn mapmap,, FigurFiguree 1)1):: twinnetwinnedd crystalcrystalss anandd aass sharsharpp oorr rounderoundedd frag­frag­ Espirito Santo. TheThe TriunfTrillnfoo prospecprospectt (Santa(Santa TereTere­­ mentsments,, pebblepebbless anandd gravelsgravels.. ThThee fine specimenspecimenss araree ssaa townshiptownship)) lieliess 1.1.55 kilometrekilometress ttoo ththee ESESEE ooff eagerleagerlyy soughsoughtt afteafterr bbyy mineraminerall collectorscollectors.. WithoutWithout ItaranItaranaa towntown.. A subverticasubverticall pegmatitepegmatite,, ononee metremetre industriaindustriall importanceimportance,, chrysoberychrysoberyll iiss onlonlyy soughsoughtt widewide,, runninrunningg NW-SNW-SEE anandd outcroppinoutcroppingg aass a gossagossann foforr ititss gegemm crystalcrystalss ooff whicwhichh threthreee typetypess araree resultinresultingg frofromm biotitbiotitee weatheringweathering,, was workeworkedd

©ICi CopyrighCopyrightt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-1250022-12522 333344 JJ.. Gemm.Gemm.,, 19931993,, 2323,, 6

o 100 km I ,

Fig.Fig. I.1. LocationLocation mapmap ofof thethe chrysoberyJchrysoberyl depositsdeposits inin Brazil.Brazil. betweenbetween 240240 andand 270270 metresmetres inin elevation.elevation. TheThe pegmatitepegmatite producedproduced chrysoberylchrysoberyl crystalscrystals reachingreaching pegmatitepegmatite isis zonedzoned withwith a biotite-feldsparbiotite-feldspar zonezone upup toto 1.51.5 kilogramskilograms inin weightweight (1.(J. Gomes,Gomes, personalpersonal alongalong thethe wall-rockwall-rock (a(a graniticgranitic gneissgneiss withwith feldsparfeldspar information).information). DuringDuring 1940,1940, trillingtrilling twins,twins, severalseveral phenocrysts)phenocrysts) andand a milkymilky quartzquartz corecore containingcontaining centimetrescentimetres inin diameter,diameter, werewere collectedcollected byby KaplanKaplan smallsmall cavitiescavities fromfrom whichwhich chrysoberylchrysoberyl waswas recoreco­­ (Interview,(Interview, 1980),1980), fromfrom a weatheredweathered pegmatitepegmatite (or(or vered.vered. AnAn 8 kilogramskilograms almostalmost opaqueopaque V-twinV-twin isis itsits eluvium?),eluvium?), locatedlocated inin thethe LavraLavra (=(= mine)mine) ooff reportedreported fromfrom thisthis deposit.deposit. AntonioAntonio CoelhoCoelho (M.(M. LuqueLuque property).property). TheseThese crys­crys­ NearNear SantaSanta Leopoldina,Leopoldina, anotheranother excavationexcavation inin talstals areare famousfamous worldwideworldwide andand commonlycommonly labelledlabelled J.J. Gemm.,Gemm., 1993,23,61993, 23, 6 335335

C">o. IJ) .~ ...... ~ ~ RE Pii 't>A~'ft~:?ra Nova Correqo Boa Vista •

. -,___. ' t ..Lavra do Ribeiroo RIBEIR~O DE SA,NTANA""'J' Mor~n~o"'III!" Ze inho i1indrp Pica Pau Corrello dos Ferreiras Goa~ahn~o _ I Z qumho Fai I a II -- - } e \.. on~a ••• . _. • ...... - ...... _'•• _ Corrello do ~8 • Japones e ~' .aisco I F ZENDA • CiscoCl) MaUriCIO K M':' .Mauncio DA FAISCA e enne d~y . ura' ~ .• e Barro P{e~ • ~Inc. e Topcizla Baillaa, Simeilo •• e e Crisalita Manuel Pica Pau Corrello do Gil e e ePa SUjoe!c~rrelio das __ •• Gameleira, -f Limoeiro. . . elmirio Corrella do Veado Pnmltlv " Curindiba • Valtinho CorreQO do Martim

RodriQues ·CorreQO

• Detrital deposits, Pellmatitic deposits, o...' ___ -.Jl' 5 km 8 o 0 Towns ond hamlets

• CorrellO Surucucu

• Genipapinho

Fig.Fig. 2.2. DetaileDetailedd mapmap ofof thethe chrysoberylchrysoberyl depositsdeposits iinn C6rregoCörrego dada FaiscaFaisca area.area. 336 J. Gemm., 1993, 23, 6

as coming from Itaguaçu. kilometres to the south of Itaipé town) and 'in Chrysoberyl in quartz, near Castelinho various beryl-bearing pegmatites', in the Rio (Cachoeiro do Itapemirim township) is briefly Mucuri basin. To the south of the State, near reported by Leonardos (1945a), and by Wohlers Manhumirim town, another pegmatite was re­ (1941) as being near Santa Teresa. ported as having produced chrysoberyl twenty Minas Gérais. During 1990, on the right side of years ago (J. Gomes, personal communication). the Cörrego (= creek) Barro Preto, a thin pegmatite Bahia. Misi et al. (1975) report, without more was prospected by a trench, 50 metres in length, at information, 'simple pegmatites' chrysoberyl- the elevation of 740 metres. The occurrence is bearing, in the southern part of the State. The located 14 kilometres to the ESE of Padre Paraiso deposits are caved in. town (see detailed map, Figure 2), and near the top Rio de Janeiro. Menezes (1982) reported chry­ of a bald inselberg made of kinzigite with large soberyl in the Faraö de Baixo pegmatite (Conceiçâo garnets and platy sekaninaite crystals. The unzoned do Macacü township). Panning the dumps of pegmatite, crossed by aplite veins, running N30°E various caved in adits, none produced chrysoberyl. and dipping 75°NW to vertical, is some centimetres Cearâ. Near the town of Fortaleza, capital of the wide with swellings reaching up to 0.5 metre in State, and 1.6 kilometres to the east of the Cristais width. The pegmatite is composed of grey xeno- town, gem chrysoberyl was reported as having been morphic quartz, K-feldspar with some crystals found in the Caboquinho pegmatite. The deposit, reaching up to 15 centimetres in length, large biotite running N30°W, was worked by an open pit, 120 plates, green and pink fluorapatite, garnet and metres in length, 40 metres in width and 20m in chrysoberyl crystals which are honey yellow to dark depth. Associated minerals are: albite, beryl, cas- green in colour, thin, frequently flattened, com­ siterite, columbite, muscovite and spodumene monly V-twinned. It is an exception if they reach up (Limaverde, 1980). to 5 centimetres in length. From a more general standpoint, Costa Sena In the neighbourhood, 9 kilometres to the S SE of (1881) wrote that chrysoberyl proceeds from quartz Padre Paraiso, another pegmatite, known as Lavra veins and Leonardos (1945a) observed the same do Mauricio, was partially worked in open pit on the mineral 'in feldspar'. top of a long hill made of biotitic granite, at the The scarcity of the known deposits in rocks is elevation of 800 metres. In the open pit, partially highly disconcerting, even when, as it will be seen caved in, the weathered pegmatite involving many later on, chrysoberyl is broadly scattered in the xenoliths, appears vertical, running EW and 5 to 6 detrital deposits where it is worked from many metres wide. Typical minerals of the aquamarine occurrences. It must be pointed out that chry­ deposits may be observed in the dumps: quartz soberyl is not reported from aquamarine deposits, crystals formed by three pyramids, biotite with while the near alluvium, sometimes only several hematite layers (Cassedanne et al., 1992), musco- hundreds of metres away, frequently contain vari­ vite, black quartz and colourless topaz. According able amounts of it. In order to explain this observa­ to A. Tavares (personal communication), the tion it was pleaded that the small size of many pegmatite (or its eluvium?) would have produced chrysoberyl crystals included in quartz or feldspar some kilograms of greenish-yellow to greenish-grey, make them almost unperceivable, that beryl would highly shredded, chrysoberyl crystals. have a different distribution in the pegmatite bodies Until 1980, nine kilometres to the ESE of Coroaci or, in the old prospects, the belief that chrysoberyl town, that is to say 40 kilometres to the WNW of brought bad luck caused it not to be mentioned Governador Valadares, the Escadinha prospect was (Elawar, 1974). worked by small trenches and rooms, 60 metres in Research in numerous aquamarine-bearing length along the outcrop. The deposit, located on pegmatites (Cassedanne et al., 1992) confirmed that the left side of the Grota (= gulch) do Xuxü, at an chrysoberyl does not coexist with aquamarine in its elevation of 450 metres, is a rosary-shaped pegma­ Brazilian primary deposits. Therefore, it may be tite, 0 to 0.3 metre in width, running SSE-NNW concluded that chrysoberyl occurs in quartz (with and dipping 20°NE. The wall-rock is a garnetifer- feldspar and mica) veins and in thin pegmatites, ous mica schist. The unzoned pegmatite is made of devoid of aquamarine and judged almost without malodorous grey quartz, kaolinized feldspar, abun­ economic interest in outcrop, on account of their dant muscovite, garnet and flattened chrysoberyl narrowness. According to the textural-paragenetic crystals, frequently occurring in the quartz. Fine evolution scheme of Vlasov (1952 - modified in cat's-eyes are recorded from this deposit. Cassedanne, 1990), the chrysoberyl-bearing Leonardos (1945b) referred to yellow chry­ pegmatites occur close to the base of the aquamar­ soberyl in a beryl-bearing pegmatite located in the ine producing zone. Cörrego Surucucu; in Sebastiâo Ferreira (30 Gem-bearing pegmatites were dated to 450-520 J. Gemm., 1993, 23, 6 337

Fig. 3. Trilling twinned crystal (4.5 centimetres in diameter) from the Itaguaçu area (Espirito Santo State).

Fig. 4. V-twinned partly gemmy crystal (3 centimetres in Fig. 5. Waterworn chrysoberyl crystal weighing 325 grams length) from the Cörrego da Faisca area (Minas Gérais from Pancas area (Espirito Santo State). State). 338 ]. Gemm., 1993, 23, 6

Fig. 6. Large V-twinned crystals from a recent find in C6rrego Alegre (Espirito Santo State). From left to right the samples weigh 1730, 830 and 880 grams. K. Elawar collection.

myoid in the east centre of Minas Gerais State. In the Socot6mine, to the NE of Campo Formoso They are always considered as belonging to the last town, a steeply dipping, running NNE-SSW sequ­ phase of the Brazilian tectonic cycle, when em­ ence is made of gneiss, quartzites and talc-schists placed in granites or its wall-rocks, or may have associatedwith peridotites and serpentinites, cut by been slightly later (Correia Neves etal., 1986). thin granite pegmatites. As is done in Carnaiba, emerald is worked in the sludite lenses. Alexandrite Granitepegmatites associated with ultramaficrocks and chrysoberyl are rare, sometimes associatedwith large rounded milky phenakite crystals. Chrysoberyl (alexandrite) from these deposits is Lastly, a very little alexandrite sporadically a by-product of emerald mining. See Schwarz appears in the Belmont emerald mine, near Itabira (1987) for more details regarding this gem and its (State of Minas Gerais). deposits. In the large Carnaiba mine, 30 kilometres to the Detritaldeposits south of Campo Formoso town (Pindobacu A series of physical and chemical superficial township, State of Bahia) located on the western phenomena take place in the primary deposits slope of the Serra de Jacobina, alexandrite is which lead to the formation of gem-bearing allu­ associated with emerald mainly in the Marota and vium. Vario~s types of deposits may be correlated to Lagarto prospects. In another, called Mundell, intermediate stages during this formation. chrysoberyl is found in biotite schist lenses in In tropical countries a number of pegmatite which it occurs as flattened trilling twins measuring minerals are unstable under superficial conditions, up to 5 centimetres in diameter, but almost without at least on geological time scale. Some minerals translucent parts (Bruni, 1976). The Serra de change into clay (feldspars, spodumene), others Jacobina is made of a quartzite sequence with schist decompose (biotite, magnetite, garnet) leading to intercalations and ultramafic rocks sills (where the disintegration of the pegmatite body, while chromite deposits are worked), intruded by a chemically stable or practically insoluble com­ granite batholith and its pegmatite vein satellites. pounds such aschrysoberyl, beryl, topaz or tourma­ Emerald is found near the contactofthe pegmatites. line, remain unaltered and concentrate with heavy It is in a micaceous rock called sludite made of minerals such as cassiterite, ilmenite, monazite, phlogopite, a little quartz, apatite, biotite, molybde­ niobotantalite, rutile and zircon. When the weath­ nite and minor scheelite and alexandrite. The ering-resistant products stay plumb with or very deposit, the production of which reaches some near to the pegmatite, they are either scattered in a hundreds of tons of emerald of greatly variable reddish-brown sandy clayor are submitted to a light quality, is hand worked by means of shafts and grade increase, by elimination of fine particles, adits. The scattered prospects cover several square caused by meteoritic water action, forming the kilometres. so-calledeluvialdeposits. The previous detritus may J.J. Gemrn.,Gemm., 1993,1993, 23,23, 6 339339

slideslide downdown thethe slopes,slopes, formingforming colluvium depositsdeposits durinduringg newnew erosionerosion cycles,cycles, withwith steeplysteeply sidedsided beforebefore reachingreaching thethe bottobottomm ofof thethe valley,valley, wherewhere theythey valleysvalleys moremore thanthan 300300 metresmetres inin depth.depth. TheThe downdown areare pickedpicked up,up, transportedtransported andand depositeddeposited severalseveral cutting,cutting, relatedrelated toto thethe RiRioo dasdas VelhasVelhas (Upper(Upper timestimes byby thethe runningrunning waters.waters. ThisThis processprocess allowsallows Cenozoic)Cenozoic) andand Paragua~uParaguaçu (Pleistocene)(Pleistocene) cycles,cycles, waswas gemsgems andand resistantresistant heavheavyy mineralmineralss toto concentrate,concentrate, spasmodicspasmodic withwith shortshort accretionaccretion andand planationplanation byby eliminationelimination ofof lightlight particles,particles, andand leadsleads toto thethe periods.periods. TheThe accretionaccretion phasephasess areare markedmarked byby shredsshreds formationformation ofof alluvial deposits (placers (placers or or flats). flats) . IfIfthe the ofof terracesterraces remainingremaining percheperchedd uponupon thethe highhigh slopes.slopes. precedingpreceding cyclecycle isis repeatedrepeated atat differentdifferent levels,levels, CommonlyCommonly thesethese veryvery oldold terracesterraces areare buriedburied byby distinctdistinct inin time,time, itsits resultresult willwill bebe thethe constructionconstruction ofof colluviumcolluvium andand onlyonly appearappear byby chance,chance, whenwhen artifi­artifi­ superimposedsuperimposed terraces (see (se eFigure Figure 7). 7) . cialcial workwork cutscuts thethe slope.slope. OtherOther lower,lower, butbut veryvery TheThe chrysoberylchrysoberyl detritaldetrital depositdepositss areare remarkablyremarkably extensive,extensive, terracesterraces occuroccur inin thethe RioRio DoceDoce tributariestributaries developeddeveloped inin thethe north-eastnorth-east ofof thethe MinasMinas GeraisGérais andand variousvarious smallsmall coastalcoastal riversrivers (Rio(Rio Mucuri,Mucuri, forfor State,State, southsouth ofof thethe BahiBahiaa StateState andand westwest ofof EspiritoEspirito instance).instance). TheThe importantimportant precedinprecedingg morphologicalmorphological SantoSanto State,State, thethe areaarea belongingbelonging toto thethe 'Eastern'Eastern featuresfeatures commonlycommonly areare dateddated UpperUpper PleistocenePleistocene -- pegmatitepegmatite Province'Province' ofof PaivaPaiva (1946)(1946).. LowerLower HoloceneHolocene (Meis(Meis et al., 1981)1981) andand explainexplain thethe OutliersOutliers ofof anan oldold peneplainpeneplain occuroccur atat thethe summitsummit importanceimportance ofof erosionerosion inin thethe dismantlingdismantling ofof thethe ofof somesome inselbergsinselbergs toto thethe northnorth ofof Te6filoTeöfilo OtoniOtoni primaryprimary chrysoberylchrysoberyl deposits.deposits. towntown andand nearthefrontierwithnear the frontier with thethe StateState ofof Bahia,Bahia, asas InIn ththee southsouth ofof thethe BahiaBahia State,State, thethe newernewer erosionerosion extensiveextensive highhigh plainsplains preservepreservedd inin clayeyclayey andand sandysandy cyclecycle appearsappears asas vastvast pedimentspediments gentlygently slopingsloping CenozoicCenozoic sediments.sediments. TheThe peneplain,peneplain, thatthat culmin­culmin­ dowdownn towardstowards thethe AtlanticAtlantic ocean,ocean, butbut lightlylightly risingrising atesates betweenbetween 800800 andand 900900 metresmetres inin elevation,elevation, upup fromfrom southsouth towardstowards north.north. BroadBroad valleys,valleys, wherewhere belongsbelongs toto ththee SouthSouth AmericanAmerican erosionerosion cycle,cycle, dateddated almostalmost allall chrysoberylchrysoberyl prospectsprospects areare located,located, gashedgashed lowerlower CenozoicCenozoic (King,(King, 1956)1956) andand extendsextends toto thethe thethe precedingpreceding pedimentspediments beforbeforee beinbeingg partlypartly filled.filled. southsouth ofof thethe StateState ofof BahiaBahia andand nearnear thethe frontierfrontier InIn ththee interior,interior, hanginghanging valleys,valleys, sitedsited upstreamupstream werewere betweenbetween thethe StatesStates ofof MinasMinas GeraisGérais andand EspiritoEspirito thresholdsthresholds ofof resistantresistant granitigraniticc rocksrocks whichwhich pro­pro­ Santo.Santo. ducedduced waterfallswaterfalls andand actedacted asas trapstraps forfor thethe chry­chry­ TheThe SouthSouth AmericanAmerican peneplaipeneplainn waswas dissecteddissected soberylsoberyl andand heavyheavy mineralsminerals (Cachoeira(Cachoeira dodo Mato,Mato,

Fig.Fig. 7.7. TypesTypes ofof chrysoberylchrysoberyl depositsdeposits inin anan idealizeidealizedd section.section.

WITHOUT SCALE

1 - Granitic pegmatite, 2 - Granitic pegmatite associated with mafic and ultramafic rocks, 3 - Eluvium, 4 - Colluvium. a/high colluvium, b/gem-bearing low colluvium, c/barren low colluvium covering a flat, 5 - Terrace, 6 - Alluvium with gem- beoring grovel (flot). 340 J. Gemm., 1993, 23, 6

Jaquetö, Pau Brasil, etc.): erosion migrating to­ gems is made during the excavating, sometimes wards the heads of the rivers did not have sufficient with screening of the finer sized overburden. time to level the streams after the falling to the last base level. Colluvial deposits By slow creep eluvium imperceptibly passes to Eluvial deposits high slope colluvium. The limit between the two In the eluvium, commonly lateritic, the rough or types is merely conventional and only founded on slightly rounded gems are preserved in the soil, their topographic situation. Mineralized high slope their surfaces being coated by ferriferous plastic colluvium is always hand worked. reddish clay. The deposits, also called 'Chapada' (= Colluvium is generally of low economic import­ high plain or plateau), as well as those of the high ance, the gems becoming diluted among a great deal colluvium, are located upon the outliers of the of barren detritus sliding down the slope. South American peneplain or upon later piedmont The low slope colluvium represents, in the vicinity slopes or planation surfaces. These deposits, of of the alluvium, the result of the slight creep which superficial extension may reach tens of phenomena. This creep is accompanied by impor­ hectares, were extensively worked by means of tant mineralogical changes: the reddish-brown to irregular pits, small shafts of variable section and reddish soil of the high slopes changes in the large irregular excavations. All were haphazardly foothills to ochre or light brown in colour. Likewise, dug because no superficial clue exists to guide the decrease of the magnetite and its alteration pro­ research. No well defined mineralized horizon ducts, is counterbalanced by increase of ilmenite occurs, but deposits of variable thickness composed and/or monazite percentage in the heavy minerals of brown to reddish, sandy argillaceous layers with fraction. Resistant mineral reloading occurs locally. erratically distributed gems, associated with many In a sandy argillaceous soil reaching up to 10 metres milky quartz fragments, are found (Cörrego da in thickness, with some detrital quartz fragments, Faisca). Locally gem bearing layers become indi­ the chrysoberyl crystals and fragments are dissemi­ vidualized in the eluvium, as thin discontinuous nated and worked by way of large irregular excava­ lenses. Mineralogically speaking, the eluvium de­ tions, with vertical walls, always hand dug, as in the posits are poor, with some variably martitized Curindiba prospect. magnetite granules, limonitic pisolites and quartz, When no chrysoberyl occurs in the upper layers, associated with the chrysoberyl in the coarse frac­ barren colluvium of variable thickness may cover tion of the soil. The mass of the fine heavy fraction is the gem-bearing outer alluvium (Corregos do Gil made of magnetite and its alteration products, and do Fogo, Belmirio, etc.). For instance, at the associated with ilmenite and a very small amount of Dimäo prospect and vicinity, near Sâo Joâo Grande biotite, garnet, leucoxene, monazite, muscovite, (Espirito Santo State), working of the mineralized niobotantalite, tourmaline, xenotime and zircon. gravel leads the diggers to search for its lateral It is impossible to date precisely the eluvial extension until the riverside of the early creek is deposits, all old in age, because their formation reached, that is to say below the slipped barren continued after the peneplanation of the surface colluvium. This, 6 to 8 metres thick, was stripped development which characterize them. This very with the help of a bulldozer during 1990 and 1991, long exposure to superficial weathering explains allowing the discovery of magnificent large, partly their broad extension, caused by multiple very gem-quality, V-twinned chrysoberyl crystals, some small lateral movements of their resistant compo­ of them reaching up to 2 kilograms in weight. nents, as well as their mineralogical paucity result­ ing from an exhaustive chemical weathering. Dis­ Alluvial deposits covery of eluvial deposits is always fortuitous: loose The so-called 'brejo' (= food plain) deposits are gem chrysoberyl collected during a road or trench located at the bottoms of valleys, frequently occur­ opening, fitting up of a wire fence, etc. Without ring as swampy plains where the streams meander. delay a garimpeiros' (= diggers) rush follows the The alluvial deposits vary from a few hundred discovery, sometimes involving hundreds of dig­ metres to more than 2 kilometres in length, with a gers. They turn the soil of the deposit upside down width of from some tens to some hundreds of before leaving it, regarding it as a worked out area. metres. They are oval-shaped and may succeed one It remains, at first sight, a lunar or undulating another, like a string, along one stream. Crosswise, bombarded landscape. The excavations are almost the valleys show a flat bottom leaning by a nick always hand dug, with vertical walls dependent on against the lower slopes. In section, the alluvial the eluvium stability. The brown to red colour of deposits are usually characterized by a gravel bed their wastes is typical, contrasting with the white or lying upon the bedrock and overlaid by fine grained pale grey colour of pegmatite dumps. Sorting of the sediments. See some sections of alluvial deposits as J.J. Gemm.,Gemm., 1993,23,61993, 23, 6 341341

Fig.Fig. 8.8. SectionsSections throughthrough variousvarious alluvialalluvial chrysoberylchrysoberyl deposits.deposits. CABECEIRA CORREGO CORREGO DO DO DO ROSALINO CILINDRO DIMAO FOGO GIL ...... ,. ~,.

-~ ----_ ...... ---"'---- p:.:.-~.~-

-...~ .. PRIMITIVO

FAZENDA CORREGO SOTURNO FAISCA DECA f------

_~..... ~T.;.~ ... ,-,~ .. ,.-'-~-, -_... ':.._---.0"" ...... -;"':'":-:-. - ---... --

CORREGO LAMBUZA GONCALINHO BARRO DA HEMATITA CAMISA PRETO ...... Ji

:::::::~

o Bedrock, o Gravel, o Fine sand, t-:-:':':I Coarse sand, ~ Blocky alluvium, E3. Pebbles, Colluvium, . o Light clay and silt, Reddish brown conglorriera1e, c::J Block cloy and peot, Buried trunks.

areare shownshown inin FigureFigure 88.. bedrockbedrock morphologymorphology isis typicaltypical ofof hardhard rockrock riveriverr The bedrockbedrock is ivariable,s variable but, bu invariablyt invariabl weatheredy weathere d erosion.erosion. TheThe argilizationargilization tootookk placeplace later,later, belowbelow thethe belowbelow thethe placerplacerss andand alteredaltered intointo a moremore oror leslesss alluvialalluvial overburdenoverburden resultingresulting fromfrom weatheringweathering plastiplasticc grey,grey, beigbeigee oror yellowishyellowish mass.mass. TheThe bedrockbedrock underunder a tropicaltropical climate.climate. surfacesurface isis undulating,undulating, showingshowing potpot holes,holes, canyonscanyons The gravel,gravel, commonly commonl yfairly fairl yrounded, rounded frequently, frequentl y moremore thanthan 2 metresmetres inin depthdepth (Corrego(Cörrego dodo Fogo)Fogo) andand containscontains mediummedium ttoo smallsmall sized,sized, rarerare toto abundantabundant largelarge transversetransverse ridges,ridges, oror isis asymmetrical,asymmetrical, comcom­­ pebblespebbles.. ItIt isis anan exceptionexception forfor multi-decimetremulti-decimetre sizedsized paredpared withwith thethe valleyvalley axis.axis. Frequently,Frequently, atat bothboth flatflat boulderboulderss toto occuroccur (Cilindro,(Cilindro, southernsouthern tributariestributaries ooff ends,ends, thethe solesole plateplate rises,rises, formingforming a seriesseries ofof largelarge thethe CorregoCörrego dodo Fogo).Fogo). AfterAfter a fewfew kilometres,kilometres, thethe elongatedelongated basins,basins, wherewhere gravelgravel waswas deposited,deposited, bebe­­ gravelgravel grain-sizegrain-size dIstributiondistribution downstreamdownstream quicklyquickly tweentween rockrock thresholdsthresholds whichwhich areare passedpassed byby cascadescascades decreasesdecreases andand thethe fragilefragile componentscomponents disappear.disappear. andand waterfalls.waterfalls. TheThe resultingresulting morphologymorphology leadsleads toto a SometimesSometimes smallsmall bouldersboulders oror coarsecoarse sandsand bedbedss seriesseries ofof highhigh stepssteps wherwheree hanginghanging gravelgravel bedbedss areare occuroccur inin thethe gravel.gravel. Moreover,Moreover, whawhatt maymay bbee preserved.preserved. AfterAfter gravelgravel sedimentation,sedimentation, weatheringweathering observedobserved locallylocally isis a partialpartial oror entireentire ironiron hydroxidehydroxide ofof thethe bedrockbedrock tooktook place.place. InIn orderorder toto explainexplain thisthis concretionconcretion ofof ferricrusferricrustt typtypee resultingresulting fromfrom a tropic­tropic­ observationobservation itit mustmust bebe keptkept inin mindmind thatthat thethe alal climateclimate (Belmiro,(Belmiro, Soturno)Soturno) oror a markedmarked silicifica-silicifica- 342342 J.J. Gemm.,Gemm., 1993,1993, 23,23, 6

FigFig.. 99.. HeavyHeavy mineralsminerals Accessory iinn somesome BrazilianBrazilian minerals chrysoberylchrysoberyl·- <0,1% bearingbearing gravels.gravels. o 50 100% CABECEIRA DO JACINTO I I .~. R,M CORREGO DA CAMISA r--...J..-----L...J.L...------.'-n-II-*'I BARRA NOVA fl CORREGO DA FAISCA R CILINORO 11 I: R GONCALINHO I R,T,L MR~ ~Ero I 1" R CORREGO DO GIL n n R PRIMITIVO I t.t R COIMBRAS HI:'...• ,~- R IT,F LAMBUZA I .. R,T,L SOTURNO (upper) II liill iiliiili,:I:!i.llllliiillii;l!li'"i:iiii~O;'\)~IJ~'O~O;'O;LJU ::.~. S con DO FOGO (upper) I. W:!I'ilil!il,lIlliililllli 11i!!llllllllili:Il?;Ii:'S~Clo.u,,\t';'. ~~--~~~~~~~~~~~~~~ CORR. DO FOGO (lower) 11 11!"ill!I!!'111111!!I,!','!!:!I!IIII' : ilil!:!!III!!!!!!!I!!;!1 . t .. ~~0J K CORREGO SETUBINHA m : II Fljlllll·';i: X,M,S FAZENDA DEC A ~m~ _____~I~ ______~II';'~'~' JAQUETO 1'1 ~t L ,B CACHOEIRA ALTA 1-'------T....---,I,-----'I!rY R, T, S FAZENDA DO GIL I 'I'. L DIMAO II t··· L CORREGO ALEGRE(upper) , H' • R

Ilmenite (and magnelite =m), C=:J Garnet, C=:J Monazite, c:::::J Leucoxene (L), Topaz, ~ Biotite (B), ~ Tourmoline (T),1IIIIIIIIlITI Rutile(R),~ Zircon, ll Corundum, _ Anatose, F = II Fovas , K =Kyonite 1 M = Muscovite, S = Sirlimonite, x = Xe notime.

tiotionn correspondincorrespondingg ttoo paleopaleosoil soilss (Primitivo,(Primitivo, C6rre­Cörre- contradistinctioncontradistinction toto ththee gravelgravel,, lieslies abruptlyabruptly uponupon ggoo ddoo Gil)Gil).. ThThee gravegravell isis a fefeww decimetredecimetress thicthickk andand ththee graveLgravel. ItIt isis madmadee ooff greyishgreyish,, beigebeige,, yellowisyellowishh oror iitt isis aann exceptionexception foforr iitt ttoo reacreachh upup toto 0.80.8 metre.metre. whitiswhitishh colouredcoloured,, mormoree oorr leslesss sandysandy clay,clay, argil­argil­ ThThee gravegravell iiss invariablinvariablyy madmadee ofof milkymilky quartz,quartz, laceouslaceous sandsand anandd silt,silt, irregularlyirregularly superimposed,superimposed, somesome ofof itit beinbeingg translucentranslucentt toto transparentransparentt oror smokysmoky typicatypicall ooff floodflood plainsplains.. InterbeddedInterbedded locallylocally araree richrich quartz,quartz, associateassociatedd witwithh rocrockk fragmentsfragments,, claclayy gallsgalls,, bluish-grebluish-greyy ttoo blackishblackish organicorganic mattermatter,, plastiplasticc layerslayers feldsparfeldspar iinn ververyy variablevariable amountsamounts andand,, sometimes,sometimes, a (Soturno(Soturno,, BarrBarroo PretoPreto)) withwith oror withoutwithout buriedburied littlelittle muscovitmuscovitee anandd pisolitespisolites,, inin a poorlpoorlyy developeddeveloped trunkstrunks,, testifyintestifyingg ttoo ololdd turf-moorturf-moorss establisheestablishedd inin sandsand andand clayclay matrixmatrix.. IInn thethe coarsecoarse fractionfraction (more(more ox-bowsox-bows (Rosalino(Rosalino)) wherwheree pyritepyrite neoformationneoformation thathann 2 millimetremillimetress iinn size)size) thethe chrysoberylchrysoberyl iiss sporadicallysporadically occursoccurs (Cörreg(C6rregoo dodo Fogo)Fogo).. SometimesSometimes associatedassociated with:with: aquamarineaquamarine,, garnet,garnet, schorlschorl (locally(locally thithinn bedbedss ooff cross-beddecross-beddedd coarsecoarse sandsand attesattestt ttoo shortshort withwith indicolitindicolitee oror rubellite),rubellite), topaztopaz,, amethystamethyst,, smokysmoky renewerenewedd torrentiatorrentiall erosioerosionn periodperiodss (Barr(Barroo Preto).Preto). quartzquartz,, rosrosee quartquartzz and,and, iinn lesselesserr amountamount,, andalu­andalu- SandySandy oror sand-free,sand-free, kaolikaolinn layerslayers andand beigbeigee argil­argil­ site,site, iroironn oxides,oxides, niobotantaliteniobotantalite,, rutilerutile,, sapphire,sapphire, laceoulaceouss browbrownn mottlemottledd horizonhorizonss evokeevoke paleosoilspaleosoils.. A zirconzircon andand moonstone.moonstone. ResearcResearchh upouponn thethe finefine mantlmantlee ofof largelarge boulderboulderss descendingdescending fromfrom thethe steepsteep fractiofractionn ofof pannepannedd heavheavyy mineralmineralss (Figure(Figure 9)9) rere­­ slopesslopes overhangingoverhanging ththee streams,streams, isis rarelrarelyy presentpresent sultedsulted iinn thethe findingfinding of:of: anataseanatase,, andalusiteandalusite,, apatite,apatite, (Cilindro).(Cilindro). TheThe overburdenoverburden iiss alwayalwayss thickerthicker thanthan biotitebiotite,, berylberyl,, cassiterite,cassiterite, chrysoberylchrysoberyl,, chrysocolla,chrysocolla, ththee gravelgravel,, reachinreachingg upup ttoo 4 metremetress iinn thickness.thickness. cordieritecordierite,, corundum,corundum, gahnitegahnite,, garnet,garnet, hematite,hematite, ItIt growgrowss thinnerthinner towardtowardss ththee headsheads.. hornblende,hornblende, ilmenite,ilmenite, kyanitekyanite,, leucoxene,leucoxene, Timo'limo­- ThusThus,, ththee alluvialalluvial depositdepositss correspondcorrespond ttoo mormoree oror nite'nite',, magnetite,magnetite, malachitemalachite,, muscovite,muscovite, nontronite,nontronite, leslesss sortedsorted torrentiatorrentiall layerslayers belonginbelongingg toto anan oldold niobotantaliteniobotantalite,, pyrite,pyrite, rutile,rutile, sillimanite,sillimanite, staurolite,staurolite, erosioerosionn period,period, abruptlyabruptly overlaioverlainn bbyy finefinerr sedimentssediments rare-earthsrare-earths coatings,coatings, topaztopaz,, tourmalinetourmaline,, wolframite,wolframite, ooff a moremore eveneven regime.regime. FrequentlyFrequently thethe proximitproximityy ooff xenotimxenotimee anandd zirconzircon.. SeeSee foforr mormoree detaildetailss Cassedan­Cassedan- ththee gem-bearinggem-bearing sourcesource rocksrocks maymay bbee inferredinferred fromfrom nencetal. et al. (1984)(1984).. fielfieldd observation:observation: larglargee chrysoberylchrysoberyl crystalcrystalss pointpoint The overburden, barrenbarren andand alwaysalways finefine grainedgrained inin ououtt thethe proximitproximityy ofof mormoree oorr leslesss brokebrokenn downdown J. Gemm., 1993, 23, 6 343

pegmatites which, apparently, have never been sought after by prospectors (Sâo Joâo Grande, Jaquetö or Cörrego da Faisca). Frequently the nearness of pegmatites may even be inferred by: the abundance of sharp-edged topaz and muscovite crystals (Cabeceira do Jacinto), metre sized blocks of roze quartz (Alto Lagoa), almost unaltered biotite (Pail Brasil) or quartz from the graphic pegmatitic zone (Rosalino). However, it must be pointed out that, frequently, the chrysoberyl and some associated minerals are more rounded than the rest of the gravel. This observation demonstrates the importance of the relatively long transit creep­ ing, accompanied by the red clay abrasion between the source rocks and the alluvium. The main geomorphological features of the pre­ sent relief were in the same position from the beginning of the alluvial deposits formation. In the valleys subjected to tropical and arid climates, in potholes, canyons and basins developed between the falls, which were remainders of former erosion cycles. From turbulent mud flows, the gravel deposition probably took place during local violent floods of short duration. Unsorted fragments com­ ing down from the sparsely wooded adjacent slopes, or resultant from previous floods, were transported a short distance. Towards the end of every flood, a vanning of the finer particles took place. During this period, mechanical erosion augmented a weak Fig. 10. Two stage excavation of a pit. Soturno alluvial deposit chemical erosion. As consequence of a rapid clima­ (Minas Gérais State). tic change, the earlier conditions were reversed: a present seeping water is removed by small motor predominantly dry climate may follow a tropical pumps. Finally, the gravel is washed upon a coarse one where, under a thick forest, the chemical sieve and the residue thrown into the now flooded erosion predominates. Assisted by a deep rock pit. The sorting by hand of the highly coloured weathering, this erosion will supply fine and argil­ gems, among the prevailing milky quartz, is easy. laceous sediments to the valleys. During this Sometimes, part of the overburden is scraped by period, marshes settle in the bottoms, where impor­ bulldozer (Cörrego da Faisca, Cörrego do Fogo, Sâo tant terrigenous sedimentation and euxenic lens Joâo Grande), after draining of the flat by some deep formation takes place, after the sudden decrease of trenches, or diverting the stream. Ground sluicing is the stream flow. Locally, temporary accidents dis­ rarely used (Cörrego Topâzio, tributary of the turb the terrigenous sedimentation. The chry- Cörrego da Faisca). soberyl-bearing gravels probably were deposited Locally, working is done using a 'dredge', a small during a dry climatic period approximately 40,000 horizontal gravel pump set upon a steel pontoon. years ago (Turcq et al., 1987). After building a dam, part of the deposit is flooded, The search for alluvial deposits empirically is then the overburden is pumped out as mud and made by means of short pits haphazardly sunk in rejected downstream below the dam, where a new the flats. If gems are unearthed, the swampy or flat is reconstituted. Locally buried trunks make uninhabited valley converts into a diggers ant hill dredging difficult. When the gravel is almost out­ after a garimpeiro's rush. They turn the flat of the cropping, a pit is sunk to the bedrock and water new deposit upside down before leaving it, regard­ supplied by a stream deviation. The gravel is ing it as a worked (or not) area. Commonly working shovelled into the pit and mixed with a lot of water, is done by a reduced garimpeiros team. A timbered before pumping and discharging upon a tilted sieve square pit, a few metres in size, is sunk down to the with a 3 to 5 millimetre aperture. The undersize bedrock, the overburden being indiscriminately passes through the sieve towards the dumps, but dumped roundabout. When the gravel is reached, it gravel and pebbles are secured and hand sorted. is piled up on the flat surface, near the pit, the When gravel cannot be exposed, because water is argilized bedrock being carefully cleaned up. Ever too abundant, it is directly pumped out from the 344 J. Gemm., 1993, 23, 6

Fig. 11. Removing a peat horizon in the overburden. Corrego do Fogo alluvial deposit (Minas Gérais State).

Fig. 12. Washing and sorting the chrysoberyl-bearing gravel. Rosalino prospect in the Corrego do Fogo alluvial deposit (Minas Gérais State). J.J. Gemm.,Gemm., 1993,1993, 23,23, 6 343455

1956).1956). PresentlyPresently thesethese deposits,deposits, wherewhere chrysoberylchrysoberyl waswas associatedassociated withwith andalusite,andalusite, sillimanite,sillimanite, spo­spo- dumenedumene andand colouredcoloured tourmalines,tourmalines, havhavee beebeenn work­work­ eded outout oror abandonedabandoned andand areare mainlymainly ofof historicalhistorical interest.interest. TheThe actualactual outputoutput proceedproceedss fromfrom thethe PadrePadre Paraiso-Americanas,Paraiso-Americanas, MalacachetaMalacacheta andand ItabiraItabira areasareas,, wherewhere almostalmost allall activeactive prospectprospectss areare located.located. BetweenBetween Padre ParaisoParaiso and and Americanas, Americanas, about abou t90 9 0 kilometreskilometres toto thethe NNENNE ofof Te6filoTeöfilo OtoniOtoni town,town, a greatgreat numbernumber ofof prospects,prospects, somesome workedworked forfor moremore thanthan 5050 years,years, comprisecomprise thethe largerlarger concentrationconcentration ooff chrysoberychrysoberyll workingsworkings iinn BrazilBrazil,, makinmakingg ououtt a WNW-ESEWNW-ESE trend.trend. TheThe C6rregoCörrego BarraBarra NovaNova flowsflows toto thethe east,east, thethe C6rregoCörrego dada FaiscaFaisca toto thethe westwest andand thethe RibeiriioRibeirâo dede SantanaSantana inin thethe centre,centre, thethe lastlast twotwo beingbeing tributariestributaries ofof ththee RioRio Mucuri.Mucuri. TheThe mainmain deposit,deposit, neanearr thethe elevationelevation ofof 550550 metresmetres,, isis locatedlocated atat thethe C6rregoCörrego dada FaiscaFaisca FazendaFazenda (=(= farm)farm) dede R.R. ZimmerZimmer andand itsits smallsmall tributaries,tributaries, withwith variouvariouss prospects:prospects: CachoeiraCachoeira dodo Gato,Gato, Crisolita,Crisolita, Filuca,Filuca, C6rregosCörregos dodo Marcolino,Marcolino, LimoeiroLimoeiro andand Topazio;Topâzio; Gameleira,Gameleira, TopazinhoTopazinho andand Topaziio.Topazâo. TheThe areaarea iiss mountainousmountainous withwith balbaldd garnet-richgarnet-rich kinzigitekinzigite inselbergs,inselbergs, lookinglooking dowdownn onon deepdeep valleys.valleys. TheThe depositdeposit produceproducess chry-chry-

Fig.Fig. 14.14. DischargingDischarging thethe pumpepumpedd chrysoberyl-bearingchrysoberyl-bearing gravel.gravel. GravelGravel andand pebblespebbles areare retainedretained byby thethe sievesieve beforebefore handhand sortingsorting.. MedinaMedina alluvialalluvial depositdeposit (Minas(Minas GeraisGérais State). Fig.Fig. 13.13. WorkingWorking anan alluvialalluvial depositdeposit byby meansmeans ofof a smallsmall dredge,dredge, nearnear Te6filoTeöfilo OtoniOtoni towtownn (Minas(Minas GeraisGérais State).State). bottombottom ofof thethe floodedflooded excavation.excavation. ThisThis wayway leadsleads toto a variablevariable lossloss ofof gemsgems duringduring thethe gravelgravel dredgingdredging andand consequentlyconsequently toto a lowerlower chrysoberylchrysoberyl recovery.recovery. ThereThere areare nono reliablereliable reportsreports uponupon possiblepossible reserves,reserves, productioproductionn oror chrysoberylchrysoberyl gravelgravel grade,grade, whateverwhatever thethe prospecprospectt type.type. However,However, thethe chry­chry­ soberylsoberyl mustmust bbee valuedvalued roughlyroughly asas a fewfew gramsgrams atat mostmost peperr cubiccubic metremetre ofof gravel,gravel, ofof whichwhich gemmolo­gemmolo- gicalgical propertiesproperties areare highlhighlyy variable.variable. FrequentlyFrequently eluvialeluvial andand colluvialcolluvial gradesgrades areare farfar lower.lower. LocallyLocally somesome colouredcoloured gemstonesgemstones areare recovererecoveredd asas by­by­ productsproducts ofof thethe alluviumalluvium treatmenttreatment:: aquamarine,aquamarine, garnet,garnet, tourmaline;tourmaline; butbut industrialindustrial mineralmineral iiss nevernever recovered,recovered, althoughalthough locallylocally comprisingcomprising a substantialsubstantial partpart ofof thethe heavyheavy undersize,undersize, particularlyparticularly rutilerutile (C6rrego(Cörrego dodo Fogo)Fogo) oror monazite.monazite.

LocationLocation ofof thethe chrysoberylchrysoberyl detritaldetrital depositsdeposits Minas GeraisGérais ThisThis StateState waswas thethe firstfirst chrysoberylchrysoberyl producer.producer. FromFrom thethe eighteentheighteenth centurycentury thethe gemgem hashas beenbeen workedworked inin thethe RioRio Ara~uaiAraçuai basin,basin, nearnear thethe towntown ooff thethe samesame namename (formerly(formerly Calhau)Calhau) andand inin thethe tributariestributaries ofof ththee river:river: Calhau,Calhau, Gravata,Gravatâ, Lufa,Lufâ, Rabelo,Rabelo, Urubu,Urubu, dosdos NeveNevess (Costa(Costa Sena,Sena, 1881),1881), NovoNovo (Leonardos,(Leonardos, 1945a)1945a) andand SantaSanta MariaMaria (Arena,(Arena, 346 J. Gemm., 1993, 23, 6

soberyl and cat's-eye associated with aquamarine, data and detailed description of some deposits.) amethyst, smoky quartz (= morion), topaz and Output was mainly of chrysoberyl, with a lesser tourmaline with a little andalusite and very rare amount of cat's-eye, both associated with aquamar­ alexandrite. Garnet is abundant in the heavy pan­ ine, morion, topaz and tourmaline with rare garnet ned fraction. and andalusite. It is an exception to find alexandrite Towards the west a series of prospects exists, part in this area. of which is abandoned (see Figure 2 - in part after About twenty kilometres to the ENE of Padro Vargas, 1992): Barra Nova 1 and 2, Boa Vista, Paraiso, in the important outlying Pedra (or Corre­ Argimirio Gonçalves, Fazenda A. Tavares (Lavra do go) da Camisa prospect, more than 300 diggers were Bejû), Antonio Ramos, Cörrego dos Veados, Corre­ actively working during 1990. The flat extends go do Cisco, Cörrego do Martim, Simiâo, Cörrego about 800 metres along the stream, a little before its do Veado, Cörrego do Gil (more than 2 kilometres junction with the Rio Anta Podre, and produces long flat located ESE of the Ribeiräo de Santana chrysoberyl and cat's-eye associated with much hamlet and worked for twenty years), Barro Preto schorl, morion and topaz, with a little garnet,

Fig. 15. After removing the thick reddish barren colluvium caused by sliding, workers found large V-twinned chrysoberyl crystals in the alluvial gravel of this flat in the Cörrego Alegre (Dimâo prospect - Espirito Santo State). See the 3 crystals in Figure 6.

(working alluvium caught between kinzigite fallen andalusite, amethyst and moonstone. blocks, in one Cörrego do Gil affluent), Lavra do In the south, after an hiatus corresponding to the Ribeiräo, Gonçalinho, Mutum, Moreno, Zinco, Cörregos Marambaia and Santa Cruz basins, Cilindro and Zequinha (working a long narrow flat famous world-wide for their great aquamarine between blocks fallen in from the surrounding steep production, exists another series of prospects, slopes). To the east and south are: Faisca 1 and 2, almost all abandoned. The Lavra dos Coimbras Baixâo, Crisolita, Manoel Pica Pau, Fazenda Joâo which produced fine small alexandrites from a wide Edilberto (Cörrego das Gameleiras), Belmirio flat of the Rio Comprido must be noted. The Chico Poaiâ, Curindiba (Arlindo Miranda and Abilio Rodrigues, Cörrego Lütero and Genipapinho pros­ Preto), Primitivo Moreira and Valtinho. This re­ pects are located nearby. gion, where many gems were produced in the past The Corrego do Fogo deposit, 15 or so kilometres from alluvium, terraces and low colluvium, is also to the NNW of Malacacheta town, discovered about known as Americanas or Americaninhas, the name 1975, is one of the more important in Brazil. There, of a nearby hamlet. (See Proctor (1988) for historical between 830 and 870 metres in elevation, along the J. Gemm., 1993, 23, 6 347

full length of the stream which runs ESE-WNW in the same minerals occurring in other nearby pros­ a narrow valley, as in its southern tributaries and the pects are recovered. Cörrego Setubinha (to which flows the Cörrego do The Hematita mine (also called Nova Era and Fogo), a series of prospects succeed one another Itabira), 4 kilometres to the SSW of the homony­ (Garimpos Rosalino, da Safira, Joâo Rodrigues, do mous hamlet and 20 kilometres to the ESE of the Baiano, Abel, etc.). The deposit produces chry- Itabira town, is probably the richest alexandrite soberyl and alexandrite and a few small sapphires concentration in the world, located near the junc­ associated with aquamarine, rubellite and some tion of two creeks that flow into the Cörrego da garnet and andalusite. Alluvium is rutile-rich, with Liberdade. The flat, 200 metres in length and 150 large rose quartz boulders and, locally, pyritic peat metres wide, encloses a kaolinitic gravel, probably horizons. an eluvium or colluvium almost unsorted, in which About 10 kilometres to the north, still in the Rio the alexandrite grade is exceptionally high. The Setubal basin, the Soturno prospect works, at alexandrite fragments, with many faces, subangu- nearly 830 metres in elevation, in a narrow valley, a lar, are frequently centimetre sized. After two

Fig. 16. Cörrego da Camisa alluvial deposit, near Padre Paraiso town (Minas Gérais State).

WNW-ESE running flat, one kilometre in length. diggers invasions following the discovery in 1986, The production is the same as that at the Cörrego do the deposit is presently mechanically worked by a Fogo. Small hematite roses are common in the sole mining society, but is in the process of closing gravel. because of the exhaustion of the detrital reserves. A Approximately 20 kilometres to the north-west of few occurrences are sited in the neighbourhood. the Santo Antonio do Jacinto town, various pros­ Various other chrysoberyl localities are men­ pects are almost abandoned: Pau Brasil, Cabeceira tioned, without details, and commonly lost: Serro do Jacinto, Talismâ and Enchadâo. They produced (Ferraz, 1929), Rio Mucuri tributaries (Leonardos, chrysoberyl associated with much colourless topaz 1945 b), Caraf, Itambacuri, Joaima, Medina, Mucuri with a few cat's-eyes and aquamarines. (Abreu, 1963), Santa Luzia de Carangola (Serra dos The Lambuza prospect, to the SSW of Pavâo Arrependidos) and Fâria Lemos (Franco et al., town, is re-working a wide flat which produced 1972), Pouso Alegre (Rio Sapucaia Mirim), Rio aquamarine in the past (while chrysoberyl was not Suaçuï Grande, Minas Novas, Turmalina (Rio Ita- sought). Cat's-eye and alexandrite associated with marandiba) and Berilo (Schobbenhaus et ai, 1984). 348 J. Gemm., 1993, 23, 6

prospects are in reduced activity: Cachoeira do Mato at an elevation of 290 metres and Cachoeira Alta at 330 metres, both in hanging valleys over­ looked by inselbergs. The output is made up of chrysoberyl with very little alexandrite, associated with aquamarine and tourmaline and a little garnet and rose quartz. The prospects of Pial (Säo José do Prado), Cörrego da Areia (Medeiros Neto) and Juerana (Teixeira de Freitas) are abandoned. The latter two produced aquamarine and chrysoberyl. In the neighbourhood of Santo Antonio de Alcobaça, the Palmeiras prospect, in process of closing, worked at an elevation of nearly 150 metres, a 2 kilometres long flat cut into a broad pediment. There, alexandrite and chrysoberyl are found in association with garnet and amethyst and rare aquamarine. The nearby prospects of Coité and Cachoeira are abandoned. A deposit discovered in 1983, in the Fazenda do Gil, 500 metres from the riverside of the Rio Alcobaça, works a flat more than 1 kilometre in length, and produces chrysoberyl and alexandrite associated with aquamarine, garnet, tourmaline and rose quartz. Chrysoberyl is also reported, without details, in Jacunda and Mata Verde.

Espirito Santo The greatest deposit is that of the Cörrego Alegre (Dimäo, Minguinho, Nelson Costa, etc.), near Sao Fig. 17. Working a chrysoberyl-bearing pegmatite, during 1990, near Barro Preto (Minas Gérais State). The Joäo Grande, 20 or so kilometres to the northwest of pegmatite may be seen along the small brown step in the Colatina town. There, a string-shaped flat, more the foreground. than 3 kilometres in length, occurs through low hills Bahia with inselbergs above, between 100 and 120 metres Chrysoberyl deposits are smaller than those of in elevation. The production is made up of chry­ Minas Gérais State, mostly abandoned and located soberyl and cat's-eye. Crystals of the former with in the south-eastern region of the State (see Casse- numerous faces, frequently V-twinned and danne, 1984, for more details). In the northern area reaching more than 2 kilograms in weight, characte­ of the aforesaid region, the prospects of Säo Joäo do rize the output of this region, where the medium Sul (Olavo, Fazenda E. Motta), Guaratinga (Lavra size of the crystals, as a whole, is always greater than da Libidinosa, Fazenda Monte Carmelo), Sao in the aforesaid prospects. Moonstone fragments Paulinho, Alho (Fojö Velho, Cacheado), Imbauba are common in the gravel as are aquamarine, garnet (near Säo Joäo da Prata), Cörrego da Queixadâ, and amethyst. In the neighbourhood, the Säo Joäo Lavra da Copacabana and Lavra do Corrö Pequeno prospect is abandoned as is that of Pancas (Itanhém) are practically abandoned, and the Ja- which produced chrysoberyl and finecat's-eye . quetö prospect (Salomâo, where a very pale V- The other prospects: Vargem Alta (Franco & twinned alexandrite crystal, 6250 grams in weight, Campos, 1965), Santa Teresa area (Tancredo), was unearthed) is in the process of closing. Vargem Alegre, Ibiraçu, Fundäo (Cörrego das Near Itamaraju, to the east of the Säo Joäo da Piabas), Cachoeiro do Itapemirim and Cörrego Prata hamlet, small prospects in the flats of the Melgaço (Putzer, 1956), are practically abandoned. Fazenda Deca (Bom Jesus) and Palmito, between 90 and 100 metres in elevation, are located along Sao Paulo tributaries of the Rio do Sul. There chrysoberyl and This is the only other State where alluvial alexandrite are associated with a few cat's-eyes, chrysoberyl is reported, but without details. In the aquamarine, garnet, andalusite, tourmaline, rose Serra de Taquaxiara (near Säo Paulo city), it occurs quartz, amethyst and zircon. in the gulches that flow into the Rio M'Boi Mirim To the ENE, near Medeiros Neto town, two (Knecht, 1934). J. Gemm., 1993, 23, 6 349

Fig. 18. Partial view of the Cörrego do Fogo alluvial deposit (Rosalino prospect) where chrysoberyl is associated with some sapphire (Minas Gérais State).

Fig. 19. Typical 'inselberg' landscape of the chrysoberyl-bearing areas. Road from Colatina to Pancas (Espirito Santo State). 350 J. Gemm., 1993, 23, 6

Chrysoberyl associated with other gems partly gem quality, crystals many reaching more Chrysoberyl is frequently associated with other than one kilogram in weight. Recently a series of gems worked in alluvium, such as diamond, beryl V-twinned crystals, with marked grooves, lightly and andalusite. It is locally recovered as a by­ rounded with sides exceeding 15 centimetres in product. length, olive green to dark green, were unearthed at Chrysoberyl from the diamond-bearing gravels is Sâo Joâo Grande. The splendid, wonderful, translu­ considered a common fellow-traveller mineral (Are­ cent crenellated wheel-twins, yellow to olive green na, 1956). It is reported from the State of Bahia in in colour, reaching up to 8 centimetres in diameter, Lençois, Andaraf, Rio Paraguaçu (near Bandeira de from Ituaçu (Espirito Santo State), belong unfortu­ Melo town) and Camaçari (cat's-eye) by Hussack nately to history. The Carnaiba emerald deposit (1917) and in Limöes (Arena, op. cit.). In the State produced flat opaque hexagonal twinned crystals, of Minas Gérais, chrysoberyl was observed in several centimetres in diameter. several flats in the Jequitinhonha valley, associated Crystals found in pegmatites are commonly platy with andalusite, pyrope and hessonite (Bastos, or V-twinned (Padre Paraiso), many being heavily 1962), particularly near Diamantina (Hussak, op. shredded as a result of growing among micaceous cit.), Lavrinhas (Cassedanne, 1971) and Très Ilhas. minerals. Chrysoberyl is reported from the Sâo Paulo State by Hardness is 8.5. The fracture is conchoidal to Hussak (1917) in the Patrocfnio do Sapucai uneven and the single poor cleavage is seldom township (Rios Santa Barbara and Canoas, tributar­ observed. ies of the Rio Grande), in the Goiâs State (Rio Claro) Chrysoberyl is transparent to translucent, some­ and in the Mato Grosso State (Rio Coxim, associ­ times turning opaque due to very small black or ated with sapphire). Limaverde (1980) reports brown inclusions. It is colourless (Barra Nova), chrysoberyl in the diamond gravel of the Rio Jauru, milky (if so, not collected), pale yellow, vivid yellow, in the same State. golden yellow, greenish-yellow, greenish, greenish- A little chrysoberyl is commonly associated with grey, dark green, beige or brown, sometimes grey, the aquamarine in its alluvial deposits, mainly in the bluish-grey or blackish. The last three shades are State of Minas Gérais: Serrinha near Medina (with common in the sand fraction, but infrequent in the some alexandrite), Rios Marambaia (Cörrego do gravel, and seldom collected. Locally opalescent Felipe) and Santa Cruz (Lavra das Manilhas, Uru­ (tributaries of the Ribeirâo Americanas), the chry­ bu) valleys, among others. Chrysoberyl is also soberyl often displays chatoyancy with a sharp line, scattered in the aquamarine-bearing gravel of Juera- occurring as cat's-eye with a more or less dark na and Jaquetö deposits, in the far southern Bahia colour, golden and honey hues being the most State, as in Fazenda Antonio Boffi (near Guaranâ) sought after. Alexandrite appears greenish-blue, and near Nova Venecia, both in Espirito Santo bluish-grey, dark green or brown in daylight, turn­ State. ing pale pink, reddish, reddish-brown or purple Lastly, chrysoberyl is an accessory component of when examined for transparency before an in­ the gem andalusite-bearing gravels in the neigh­ candescent light. The Hematita alexandrite shows a bourhood of Santa Teresa town (Serra do Prego, 'fabulous' colour-change according to Koivula Ribeirâo Caldeirâo) in the Espirito Santo State. (1987): bluish-green to greenish-blue passing to pink, raspberry, 'rhodolite' or ruby in colour, while The gems other Brazilian alexandrites recovered in the past Chrysoberyl belongs to the orthorhombic sys­ change only from green to violet or pink. tem. In alluvium it occurs as rounded or sub- Lustre is vitreous to almost pearly, the streak rounded grains, chips and variably sized fragments, colourless to pale beige. As crystals are frequently sometimes as crystals. These are long or wide with large and partly transparent, faceted chrysoberyl right-angled or sub-square section, or else platy, may be more than 100 carats in weight, as compared with longitudinal grooves upon the larger faces. to the usually small faceted alexandrites. Yellow Twins are common, frequently V-shaped with or cat's-eye may weigh more than 40 carats, whereas without re-entrant angles, formed by two prisms or cat's-eye alexandrites are extremely rare and seldom flat crystals. Hexagonal wheel-twins, crenellated or weigh a few carats. not, are not rare, but quite often small. In the gravel, Mean density of yellow chrysoberyl and cat's-eye crystals are millimetric to centimetric in size, rarely is 3.68g/cm3, higher and lower measured densities reaching up to 10 centimetres in length, partly being 3.72 and 3.62g/cni3. Density of brown chry­ rounded (head of the Corrego da Faisca), in elon­ soberyl showing various shades varies from 3.75 to gated prisms or V-twinned. The Cörrego Alegre 3.80g/cm3. Alexandrite density is 3.68 to 3.70g/cm3. deposit near Colatina town (Espirito Santo State), Chrysoberyl is biaxial (+) with 2V near 70°. has been world famous for a long time for its large, Typical refractive indices of pale yellow, golden and J.J. Gernm.,Gemm., 1993,1993, 23,23, 6

greenishgreenish chrysoberylchrysoberyl are:are: 0:a = 1.744-1.7451.744-1.745 ~ß == 1.746-1.7491.746-1.749 Yy = 1.753-1.754.1.753-1.754. Exceptionally,Exceptionally, sam­sam­ plesples associatedassociated withwith gemgem andalusite,andalusite, fromfrom thethe SantaSanta TeresaTeresa areaarea ((EspiritEspiritoo SantoSanto StateState)),, gave:gave: 0:a = 1.1.74 7477 ~ß = 1.7491.749 Yy = 1.757.1.757. TypicalTypical indicesindices ofof alexandritealexandrite are:are: 0:a = 1.745-1.7471.745-1.747 ~ß = 1.748-1.7491.748-1.749 Y = 1.755-1.755- 1.1.756 756.. SomeSome palepale alexandritesalexandrites frofromm CorregoCörrego dodo FogoFogo show:show: 0:a = 1.745-1.7461.745-1.746 ~ß = 1.748-1.7491.748-1.749 Y = 1.1.754-1.755 754-1. 755,, andand a samplesample fromfrom CarnaibaCarnaiba gave:gave: 0:a = 1.7471.747 ~ß =- 1.7481.748 yY = 1.756.1-756. A 0.0080.008 toto 0.0100.010 birefringencbirefringencee iiss deduceddeduced fromfrom thethe previouslypreviously rere­­ porteportedd indices.indices. ChrysoberylChrysoberyl andand cat's-eyecat's-eye showshow a distinctdistinct pleochroispleochroismm iinn ththee yelloyelloww andand browbrownn shades.shades. AlexandriteAlexandrite,, onon thethe otherother handhand,, displaydisplayss a markedmarked FigFig.. 2020.. FinFinee tubelubess iinn a cal's-eyecat's-eye frofromm thIhee CörregCorregoo dada FaiscaFaisca areareaa ((MinaMinass GéraiGeraiss SlaleState)).. pleochroismpleochroism:: darkdark red/orangred/orangee ttoo yellowyellow/green/green.. ThThee gravelgravel graingrain surfacessurfaces araree frequentlfrequentlyy pittedpitted oror showshow impacimpactt figuresfigures frofromm whicwhichh wavywavy crackcrackss com­com­ monlymonly diverge.diverge. TriangulaTriangularr positivpositivee (Pa(Pauu BrasilBrasil)) oror negativnegativee marksmarks mamayy bbee observedobserved upouponn somsomee crystalcrystal facesfaces.. GraveGravell fracturefracture iiss sometimessometimes furrowefurrowedd bbyy paralleparallell oorr divergendivergentt scratches.scratches. BecausBecausee ooff theirtheir alluvialalluvial transporttransport,, manmanyy graingrainss showshow largelarge,, impact,impact, divergent,, undulatedundulated,, flaflatt oror conchoidalconchoidal crackscracks andand fissures,fissures, frequentlfrequentlyy producinproducingg iridescence, oorr areare invadeinvadedd bbyy iroironn oxidesoxides.. ThThee latter,, undeunderr microscomicrosco­­ pipicc examinatioexaminationn anandd aann adequatadequatee incidenincidentt angleangle,, presenpresentt a goldegoldenn gleamgleam.. SomSomee smalsmalll bayonebayonett oorr grid-shapegrid-shapedd fissures occuoccurr iinn somsomee crystalcrystalss (Santa(Santa Teresa)Teresa).. ManManyy palpalee yellowyellow,, goldegoldenn yelloyelloww oorr greenishgreenish chrysoberychrysoberyll graingrainss araree totalltotallyy frefreee ooff inclusioninclusionss oorr imperfectionimperfectionss undeunderr microscopimicroscopicc examinationexamination.. IInn otheotherr grainsgrains,, ththee mosmostt frequenfrequentt inclusioninclusionss areare fissures witwithh ververyy smalsmalll bubblebubbless (Cörreg(Corregoo ddoo Gil) oror,, FigFig.. 2121.. LargLargee tubelubess iinn a cat's-eycal's-eyee frofromm thIhee CörregCorregoo AlegrAlegree areareaa mormoree oftenoften,, finger printprintss (Cörreg(Corregoo ddaa Faisca)Faisca).. SmallSmall (Espirit(Espiritoo SantSantoo State)Slale).. negativnegativee crystalcrystalss araree scatterescatteredd oorr concentrateconcentratedd iinn paralleparallell lineliness upouponn ththee inneinnerr crystacrystall planeplaness ((BelmirBelmir­- io)io).. WheWhenn ververyy smalsmalll inclusioninclusionss araree thicklthicklyy gatheredgathered upouponn conchoidaconchoidall inneinnerr fracturesfractures,, ththee crystacrystall turnsturns milky.. LargLargee two-phastwo-phasee inclusioninclusionss araree localllocallyy prepre­­ sensentt (Lambuza)(Lambuza).. UnusablUnusablee partpartss ooff manmanyy crystalcrystalss araree duduee ttoo regularegularr oorr nnoo alternatioalternationn ooff thicthickk milkmilkyy bandbandss (cause(causedd bbyy ververyy smalsmalll inclusioninclusionss arrangearrangedd iinn stripsstrips)) anandd thinnethinnerr transparentransparentt onesones.. LittlLittlee gregreyy metallimetallicc platesplates,, probablprobablyy ilmeniteilmenite,, araree commocommonn jusjustt underneatunderneathh ththee facefacess ooff somsomee crystalscrystals,, anandd araree easileasilyy eliminateeliminatedd durinduringg ththee cuttincuttingg processprocess.. WheWhenn presenpresentt throughouthroughoutt ththee rough,, ththee crystalcrystalss turturnn opaquopaquee anandd araree thereforthereforee uselesuselesss aass gemgemss (Barr(Barroo Preto)Preto).. GoldeGoldenn rutilrutilee needlesneedles,, irregularlirregularlyy distributedistributedd anandd withouwithoutt preferentiapreferentiall orientatioorientationn araree sometimesometimess abundanabundantt (Sâ(Saoo JoàJoaoo Grande)Grande),, recallinrecallingg thosthosee occuroccur­­ rinringg iinn quartquartzz crystalscrystals.. GiibeliGiibelinn etel al. (1986(1986)) rere­­ porteportedd goethitgoethitee fibres iinn chrysoberychrysoberyll frofromm BahiBahiaa Fig. 22. Small IWO phase inclusions forming veils in a chry­ State. saberyl from Ihe Corrego da Faisea area (Minas Gerais State. Scale). 352 J. Gemm., 1993, 23, 6

Fig. 23. Iron oxides filling a fissure in a chrysoberyl from the Fig. 24. Two phase inclusions in a cat's-eye from Lambuza Cörrego da Faisca area (Minas Gérais area). (Minas Gérais State).

Fig. 25. A fine cat's-eye cabochon from Cörrego da Faisca Fig. 26. A fine banded cat's-eye cabochon, 23.51 cts in weight. (Minas Gérais State).

Fig. 27. Large faceted transparent chrysoberyl. Fig. 28. Fine faceted Hematita alexandrite seen in incandes­ cent light. J. Gemm., 1993, 23, 6 353

Fig. 29. Large two phase inclusions in a chrysoberyl from Fig. 30. Rutile needles in a chrysoberyl from Sâo Joâo Grande Lambuza (Minas Gérais State). area (Espirito Santo State).

With the exception of Hematita, no deposit has do Fogo shows a band between 680-690 (doublet), a revealed characteristic inclusions, although small partial absorption between 620 and 545 nm and crystals may be commonly observed in many gems total absorption beyond 470 nm. The weak addi­ under microscopic examination (the aforesaid cited tional lines reported by Anderson (1971) were not prospects were only a few examples among many). registered. According to Koivula et al. (1988) fluorite would be Trace elements (Ti, Sn, Fe) of the Americanas typical of the Hematita alexandrite, associated with area chrysoberyls, are identical to those of the apatite. Henn (1985) determined the following Trivandrum chrysoberyls (India - Soman et al., inclusions, for which chemical analyses are re­ 1986). It must be pointed out that in four Brazilian ported, in Brazilian chrysoberyls of imprecise loca­ alexandrites analyzed by Otteman et al. (1978) tion (because various prospects are known in each gallium reaches up to 1200 ppm associated with tin location): muscovite, andalusite and orthoclase at which diadochically substitutes for aluminium fol­ Très Barras; orthoclase and albite at Malacacheta; lowing the equation: 2 Al+3 -> Sn+4 + Fe+2. Like actinolite, talc and anthophyllite at Cörrego do alexandrite, colourless chrysoberyl contains gal­ Fogo; albite, oligoclase, anorthite and andalusite at lium (Vogler, 1986), although Schmetzer (1985) Agua Fria; andalusite at Jaqueto; the examined reports otherwise. A partial analysis of Hematita samples from Colatina were inclusion-free. Lastly, alexandrite gave 0.30-0.44 wt% Cr203, 1.11-1.59 Gübelin (1974) records radiating amiant fibres, wt% Fe203 and 0.01-0.03 wt% V203 (Proctor, 1988 sea-urchin like and biotite plates (Gübelin et al., - quoting Bank & Schmetzer). 1986) in Brazilian alexandrites of unknown origin. Conclusion Growth zones appear as narrow stripes with According to Elawar (1974) the total monthly different hues (Juerana). Twin planes may be Brazilian chrysoberyl output would be in the order sporadically observed. of 10 kilograms in weight, only 10% of which is gem Tubes varying in length and diameter, hollow or quality grade: 1% top, 3% average commercial and not, are constantly present in cat's-eye and some­ 6% lower commercial grades. The remainder is sold times in yellow or greenish chrysoberyls, but very as by-product. Production probably increased with rarely in alexandrite; they are parallel to the crystal the opening of new prospects, as was the case of the elongation. Cörrego do Fogo, before decreasing to the current All chrysoberyl varieties are free of radioactivity one kilogram monthly (Elawar, personal com­ and are subject to very little deterioration. That munication, 1992) as a result of the abandoning and property explains the easy preservation in alluvial closing of many workings. No official record of the gravels. present or recent output is available, but it is Colourless, yellow and greenish chrysoberyls and possible to warrant that the exhaustion of Brazilian cat's-eyes are not fluorescent. Alexandrite, when chrysoberyl reserves is not to be foreseen in the near light coloured, is inert under UV light (Cörrego do future. Fogo), but has a weak orange/red when its body colour is darker (Carnaiba). Acknowledgements Yellow and greenish chrysoberyls and cat's-eye The authors would like to thank Mrs K. Elawar show a wide absorption band centred at 445 nm and A. Tavares for valuable discussions and helpful (440-450) and weak lines at 485 and sporadically at information regarding the chrysoberyl deposits and 505 nm (Lambuza). Light alexandrite from Cörrego their production. 353544 JJ.. Gemm.,Gemm., 1993,1993, 23,23, 6

ReferenceReferencess Leonardos,Leonardos, O.H.,O.H., 1945b.1945b. RelaçãRela,aoo dasdas ocorrenciasocorrências dede crisoberilocrisoberilo Abreu,Abreu, S.F.S.F. dede,, 1963.1963. DiamanteDiamantess e pedrapedrass coradas.coradas. Gemolngia,Gemologia, nnoo Brasil.Brasil. Min. & Met., IX,IX, 54,54, 263-4263-4.. VIII,VIII, 3131,, 7-37.7-37. Limaverde,Limaverde, JJ.. ddee A.A.,, 1980.1980. Produção,Produfao, industrializafdoindustrialização e comercio Anderson,Anderson, B.W.B.w., , 1971.1971 . Gem testing. Butterworths,Butterworths, London.London. de gemas nono Nordeste. Nordeste. BancoBanco dodo NordesteNordeste dodo Brasil,Brasil, Fortaleza.Fortaleza. Arena,Arena, P.P.,, 1956.1956. OsOs satélitesatelitess dodo diamantediamante.. Gemologia, 1,1, 3,1-8.3, 1-8 . Meis,Meis, M.R.M.M.R.M.,, MouraMoura,, ].R.J.R. dada S.,S., Silva,Silva, T.J.OTJ.O.. dada,, 1981.1981. OOss Bastos,Bastos, F.M.F.M.,, 1962.1962. AsAs pedraspedras preciosaspreciosas ddoo BrasilBrasil.. Gemologia,Gemologia, complexocomplexoss dede "rampa""rampa" e a evolu,aoevolução dasdas encostasencostas dodo PlanaltoPlanalto VIIIVIII,, 29/30,29/30, 13-1913-19.. SudesteSudeste dodo BrasilBrasil.. Anais Acad. bras. Ciiinc.,Ciênc., 53,53, 3,3, 605-15605-15.. Bruni,Bruni, M.A.M.A.,, 1976.1976 . Carta geológicageologica do Brasil ao milionesimo.milionésimo. Menezes,Menezes, S.S. dede 0.,O., 1982.1982. CatalogoCatálogo dos principais pegmatitos dodo FolhaFolha AracajuAracaju SC-24.SC-24. MME-DNPMMME-DNPM,, Brasilia.Brasilia. Estado do Rio de Janeito.Janeito. DRNDRN,, Cent.Cent. InfInf.. Teen.,Tecn., BolBol.. Teen.Tecn. CassedanneCassedanne,, J.P.J.P.,, 1971.1971. LesLes diamantdiamantss ddee DiamantinDiamantinaa (Minas(Minas no.2no.2.. GeraisGerais,, Bresil).Brésil). GeologieGéologie eett exploitation.exploitation. Bull. AssocAssoc.. franf.franç. Misi,Misi, A.,A., AzevedoAzevedo,, H.C.A.H.e.A.,, 1975.1975. A provínciprovinciaa pegmatiticapegmatítica ddoo Gemmologie, 2929,, 7-117-11.. extremextremoo SuiSul ddaa Bahia.Bahia. Min. & Met., XXXVIII,XXXVIII, 359359,, 6-10.6-10. Cassedanne, J.P., J.P., 1984. 1984. Les gisementsLes gisements brésiliens bresiliens de chrysobéryl. de chry­ OttemanOtteman,, J.,J., Schmetzer,Schmetzer, K.,K., Bank,Bank, H.,H., 1978.1978. NeuNeuee DateDatenn zuzurr soActas beryl. 9° Congr.Aetas 9° geol. Congr. Argentino, geol. Argentino, S.C. de Bariloche, S.e. de Bariloche, V, V, AnreicherungAnreicherung desdes ElementsElements GalliumGallium inin Alexandriten.Alexandriten. NNeues eues 390-405390-405.. JahrbJahrb,. Min. Mh., 172-5172-5.. Cassedanne,Cassedanne, J.P.J.P.,, 1990.1990 . LoLoss yacimientoyacimientoss dede aguamarinaguamarinaa dedell PaivaPaiva,, G.G.,, 1946.1946. ProvínciaProvinciass pegmatiticaspegmatíticas dodo Brasil.Brasil. Bol. DNDNPM-P M­ BrasilBrasil.. AAGE publ. espec., BuenoBuenoss AiresAires,, 56-66.56-66. DFPM, 78,13-21.78, 13-21. CassedanneCassedanne,, ].P.,J.P., AlvesAlves,, J.N.J.N.,, 1992.1992. L'aigue-marinVaigue-marinee aauu Bresil.Brésil. 2 ProctorProctor,, K.K.,, 1988.1988 . ChrysoberylChrysoberyl andand alexandritealexandrite fromfrom ththee - LesLes gitesgîtes primaires.primaires. Revue de Gemmologie AFG, 111,111, 11-14.11-14. pegmatitpegmatitee districtsdistricts ofof MinasMinas GeraisGerais,, BrazilBrazil.. Gems & Gemol.,Gemol., Cassedanne,Cassedanne, J.P.,J.P, BaptistaBaptista,, N.R.N.R.,, 1984.1984 . EtudEtudee ddee quelquesquelques XXIV,XXIV, 1I,, 16-3216-32.. alluvionsalluvions àa chrysobérylchrysoberyl.. Anais Acad. bras. Cienc.,Ciênc., 5656,, 33,, Putzer, H., H., 1956. 1956. Mineralmacht M ineralmacht Brasilien. Brasilien. Deutsch. Deutsch. Brasilianische Brasilianis­ 265-81265-81.. Handelskammerche Handelskammer im São Paulo, im Sao São Paulo, Paulo. Sao Paulo. CorreiaCorreia NevesNeves,, J.H.J.H.,, Soares,Soares, A.C.P.A.e.P.,, MarcianoMarciano,, V.R.P.R.O.,V.R.P.R.O., Schmetzer,Schmetzer, K.,K., 1985.1985. FarbloserFarbloser ChrysoberyllChrysoberyll.. NatürlicNatiirlichh oderoder 1986. AA Província Provincia pegmatítica pegmatitica Oriental Oriental à luz dos a conhecimentos luz dos con­ synthetisch?synthetisch? ZZ.. Dt.Dl. Gemmol. Ges., 34,1-2,6-12.34, 1-2, 6-12. hecimentos atuais.atuais. Rev. bras. Geologia, 16,16, 1I,, 106-8106-8.. Schobbenhaus,Schobbenhaus, e.,C., CamposCampos,, D.D. ddee A.A.,, DerzeDerze,, G.R.,G.R., Asmus,Asmus, Costa Sena,Sena, J.C. J.e. da, da, 1881. 1881. Viagem Viagem de estudosde estudos metalúrgicos metalurgicos no no H.E.,H.E., 1984.1984 . Geologia do Brasil. TextTextoo explicativexplicativoo dodo mapamapa CentroCentro ddaa ProvínciProvinciaa dede MinaMinass GeraisGerais.. Anais EMOP, OuroOuro geol6gicogeológico ddoo BrasilBrasil e dada areaárea oceanicaoceânica adjacentadjacentee incluindoincluindo 112.500.000, PretoPreto,, 1,1, 95-10895-108.. depósitodep6sitoss mineraisminerais.. EscalEscalaa 1/2.500.000, MME-DNPMMME-DNPM,, Brasilia.Bra­ Elawar,Elawar, K.K.K.K.,, 1974.1974. PrincipaiPrincipaiss aspectosaspectos e a comercializa,aocomercialização ddee silia. crisoberilos.crisoberilos. Anais XXVIII Congr. bras. Geologia, PortoPorto Schwarz,Schwarz, D.,D., 1987.1987. Esmeraldas, inclusõesinc/usaes em gemas. ImpImp.. Univ.Univ. Alegre,Alegre, 7,7, 219-22219-22.. EMOP,EMOP, OuroOuro Preto.Preto. Ferraz,Ferraz, L.C.L.e.,, 1929.1929. CompendioCompêndio dos mineraes do do Brasil Brasil emformaem forma dede Smimov,Smirnov, V.I.V.l. (ed.)(ed.),, 1977.1977. Ore deposits of the USSR III.II I. PitmanPitman diccionário.dicciondrio. Imp.Imp. Nac.Nac.,, RioRio ddee Janeiro.Janeiro. publ.publ.,, London.London. FrancoFranco,, R.R.,R.R., CamposCampos,, J.EJ.E.. dede S.,S., 1965.1965. As pedras preciosas, Soman,Soman, K.K.,, NairNair,, N.G.K.N.G.K.,, Druzhinin,Druzhinin, A.V.,A.V., 1986.1986. ChrysoberylChrysoberyl noçõesnOfaesfundamentais. fundamentais. Col.Col. Buriti,Buriti, Desa,Desa, SaoSão Paulo.Paulo. pegmatites of of South South Kerala Kerala and and their their metallogenic metallogenic implications. implica­ FrancoFranco,, R.R.,R.R., Leprevost,Leprevost, A.,A., BigarellaBigarella,, J.J.,J.J., BolsanelloBolsanello,, A.A.,, Journ.tions.Journ. Geol. Soc. Geol.of India, Soc. 27 of, 411-18. India, 27,411-18. 1972.1972. Minerais do Brasil. Bliicher,Blücher, SaoSão Paulo,Paulo, I.I. TurcqTurcq,, B.,B., Suguio,Suguio, K.K.,, Soubies,Soubies, F.F.,, Servant,Servant, M.,M., Pressinotti,Pressinotti, M.M.,, Giibelin,Gübelin, E.E.,, 1974.1974. Internal world of gemstones. DocumentDocument fromfrom 1987.1987. AlgunsAlguns terraçoterra,oss fluviaifluviaiss dodo SudesteSudeste e dodo CentroCentro OesteOeste spacespace anandd timetime.. ABC,ABC, Zurich.Zurich. brasileirobrasileiross datadosdatados poporr radiocarbonoradiocarbono:: possíveipossiveiss significadossignificados Giibelin,Gübelin, E.E.,, KoivulaKoivula,, J.I.,J.I., 1986.1986 . Photo Atlas of inclusions inin paleoclimáticospaleoclimaticos.. Anais 1°/0 Congr. ABEQUA, PortoPorto AlegreAlegre,, 379-92. gemstones. ABCABC,, Zurich.Zurich. 379-92. Vargas, T.e. de M.A., 1992. ProspeCl;ao aluvionar e recon­ Henn, U., U., 1985. 1985. Veirgleichende Veirgleichende chemische chemische und und optische optische Untersuchungen Unter­ Vargas, T.C. de M.A., 1992. Prospecção aluvionar e reconhecimento hecimento geologico e geomorfologico da regiao produtora de ansuchungen Chrysoberyllen an Chrysoberyllen verchiedener verchiedenerLagerstätten. Lagerstlillen.Dissert. Dis­ geológico e geomorfológico da região produtora de crisoberilos Padre Paraiso-Americanas, Estado de Minas Dokt.sert. Dok!.Johannes Johannes Gutenberg Gutenberg Universität, Universitiit, Mainz Mainz crisoberilos Padre Paraiso-Americanas, Estado de Minas Gerais. Thesis M.Sc., Federal University of Rio de Janeiro, (unpublished)(unpublished).. Gerais. Thesis M.Sc., Federal University of Rio de Janeiro, l30p. (unpublished). HussakHussak,, E.E.,, 1917.1917. Os satélitessauilites do diamante. SGMB-MACI,SGMB-MACI, typtypo. 130p. (unpublished). Vlasov, K.A., 1952. Classification des pegmatites granitiques JornJ om.. Comercio,Comercio, RioRio ddee Janeiro.Janeiro. Vlasov, K.A., 1952. Classification des pegmatites granitiques d'apres leur texture et leur paragenese. Bull. Acad. Sc. IntervieInterview-Allanw - Allan Kaplan,Kaplan, 1980.1980. Miner. Record, 11,6,351-60.11, 6, 351-60. d'après leur texture et leur paragenèse. Bull. Acad. Sc. URSS, Serie Geol. 2, 30-55. Traduction 698 BRGM, Paris. KingKing,, L.C.L.e.,, 1956.1956. A geomorfologigeomorfologiaa dodo BrasilBrasil OrientalOriental.. Rev. bras. URSS, Série Géol. 2, 30-55. Traduction 698 BRGM, Paris. Vogler, K., 1986. Neue Untersuchungen an einem farblosem Geografia, XVIIIXVIII,, 22,147-265., 147-265. Vogler, K., 1986. Neue Untersuchungen an einem farblosem Chrysoberyll. Z. Dl. Gemmol. Ges., 35, 3-4,179-83. KnechtKnecht,, Th.Th.,, 1934.1934 . OOss mineraimineraiss e minériominerioss ddoo EstadoEstado ddee SãSaoo Chrysoberyll. Z. Dt. Gemmol. Ges., 35, 3-4, 179-83. Wohlers, A., 1941. Nota sobre 0 crisoberilo de Santa Teresa, Paulo.Paulo. SAIC Bol. Agric., 3232,, 237-323237-323.. Wohlers, A., 1941. Nota sobre o crisoberilo de Santa Teresa, Espirito Santo. Bol. Fac. Fil. Ciiinc. Letras, USp, Mineralo­ KoivulaKoivula,, ].1.,J.I., 1987.1987 . GeGemm newsnews.. ColouredColoured stonesstones.. BrazilianBrazilian Espirito Santo. Bol. Fac. Fil. Ciênc. Letras, USP, Mineralogia gia 4,39-41. alexandrites.alexandrites. GemsGems& & Gemol., XXIII,XXIII, 22,123., 123. 4, 39-41. KoivulaKoivula,, J.I.J.I.,, KammerlingKammerling,, R.R.,, 1988.1988 . GeGemm news.news. ColouredColoured stonesstones.. InclusionInclusionss identifiedidentified iinn newnew BraziliaBraziliann alexandrites.alexandrites. Gems&Gems & Gemol., XXIVXXIV,, 1,56-9.1, 56-9. LeonardosLeonardos,, O.H.O.H.,, 1945a.1945a. OcorrênciaOcorrenciass dede crisoberilocrisoberilo nnoo Brasil.Brasil. Min. & Met.,Mel., IXIX,, 4949,, 29-3029-30.. [Manuscript[Manuscript receivedreceived 2020 SeptemberSeptember 1992]1992] J. Gemm., 1993, 23,6 355

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JaspersJaspers fromfrom SwierkiSwierki nearnear NowaNowa Ruda,Ruda, LowerLower Silesia,Silesia, PolandPoland Prof. W. W. Heflik*, Heflik*, Prof. Prof. M. Pawlikowski,M. Pawlikowski, M.Sc., M.Sc, En!!.*, Eng.*, T. Sobczak, T. Sobczak, GG, FGG** GG, FGG** and Prof. and N. Prof N. SobczakSobczahfT

* AcademyAcademy ofof MiningMining andand Metallurgy,Metallurgy, CracowCracow,, PolandPoland **Warsaw,** Warsaw, PolandPoland + t PolisPolishh StandardizingStandardizing Committee,Committee, Warsaw,Warsaw, PolandPoland

AbstracAbstractt ThThee papepaperr presentpresentss ththee resultresultss ofof mineralogical­mineralogical- petrographicapetrographicall anandd geochemicageochemicall studiesstudies ooff jasperjasperss occurrinoccurringg amongamong PermianPermian melaphyremeiaphyress (weathered(weathered I ~ gp 11 basaltsbasalts,, ofteoftenn amygdaloidalamygdaloidal (mandelstones))(mandelstones)) andand por­por­ phyries in the vicinity of Swierki near Nowa Ruda. 0 phyries in the vicinity of Swierki near Nowa Ruda. 1 0 ° 0° JaspersJaspers forformm a layerlayer uupp ttoo 1.8m1.8m thickthick.. TheTheyy mainlymainly 12 consistconsist ooff silicasilica representerepresentedd bbyy chalcedony,chalcedony, opalopal anandd quartz,quartz, asas welwelll asas somesome admixtureadmixturess ooff dolomitdolomitee anandd ~ 3 micas. TheyThey areare veryvery interestinginteresting asas aa decorative decorative material. material . TheirTheir origioriginn appearappearss relaterelatedd ttoo low-temperaturlow-temperaturee hydhyd­­ gg ~ rothermarothermall silificationsilification ooff sedimentarysedimentary rockrockss occurringoccurring among melaphyres. among meiaphyres. 'V , ~ ) ~o ~ 1··.= : .-'0 ---' 5 'V 'V 'V 'V IntroductioIntroductionn \' fJ fJ 0 0 0 33.. ololdd crystallincrystallinee seriesseries..

FigFig.. 2.. LithologicaLithologicall profilprofilee ooff PermiaPermiann rockrockss frofromm ththee vicinitvicinityy ooff SwierkiSwierki:: 11.. compaccompactt melaphyresmelaphyres;; 22.. mandelstonemandelstone;; 33.. porphyriesporphyries;; 44.. schistschistss intercalateintercalatedd witwithh jaspejasperr layerla yer;; 5S.. clayy shalesshales;; 66.. sandstonessandstones.. developedevelopedd aass chalcedonchalcedonyy - eitheeitherr fibrous oorr spherspher­- uliticulitic.. JasperJasperss havhavee a smoot~moothh anandd eveevenn fracturfracturee anandd theitheirr coloucolourr rangerangess frofromm brick-rebrick-redd ttoo blueblue.. BesideBesidess occasionaoccasionall idiomorphiidiomorphicc quartquartzz concentrations,concentrations, chloritchloritee anandd opaquopaquee mineraminerall inclusioninclusionss araree ververyy frequentfrequent..

GeologGeologyy ooff ththee depositdeposit ThThee jaspejasperr occurrencoccurrencee aatt SwierkSwierkii neanearr NowNowaa RudRudaa (Figur(Figuree 1) iiss associateassociatedd witwithh melaphyremelaphyress classifieclassifiedd intintoo ththee lowelowerr portioportionn ooff ththee eruptiveruptivee complexcomplex.. ThiThiss complecomplexx iiss underlaiunderlainn bbyy shaleshaless occurrinoccurringg iinn ththee totopp parpartt ooff ththee sandstonsandstonee serieseriess (Figur(Figuree 2)2).. ThThee melaphyrmelaphyree complecomplexx ooff SwierkSwierkii iiss abouaboutt 8080mm thicthickk anandd composecomposedd ooff extensivextensivee lavlavaa flowsflows partlpartlyy ooff sub-volcanisub-volcanicc naturenature.. AAnn amygdaloidamygdaloid--

©C CopyrighCopyrightt ththee GemmologicaGemmologicall AssociatioAssociationn ISSNISSN:: 0022-12520022-1252 J. Gemm., 1993, 23, 6 357

al zone has been identified in its upper part on the sure. Its amount does not exceed 15% by weight. contact with the overlying shales above which a Iron minerals are represented chiefly by hematite porphyry complex occurs classified into the second dispersed throughout the rock. Sometimes, howev­ magmatic cycle. er, their individuals, up to 0.01mm in size, show a Jasper occurring on the first level in the quarry linear arrangement accentuating the wavy struc­ forms a thick bed up to 1.5m dipping to the north at ture. The amount of iron calculated as Fe203 does angles of 3-15° and showing distinct tectonic dis­ not exceed 0.6% by weight. But this amount is turbances. The accompanying shales are thermally sufficient to impart to the rock a distinct coloration. metamorphosed and distintegrated and the Locally, in some voids and fissures the actual melaphyre is heavily fractured and altered. On the mineral succession can be easily traced: chalcedony second exploitation level jasper is best exposed in attached to the wall is overgrown by quartz which in the uppermost portion of the southern wall where it turn is overgrown by dolomite. As evidenced by the appears as a regular bed up to 1.8m thick. Also in fact that dolomite veinlets cut all the other mineral this part of the quarry jasper is surrounded by concentrations this mineral is the final crystalliza­ thermally metamorphosed shale. The jasper bed is tion product. fairly compact and can be easily worked into blocks. Most often larger occurrences of green jasper are Large blocks the size of several cubic metres are found close to the contact between the jasper bed found at the foot of the wall on level two. and melaphyre. It is dense and uniformly coloured and can be polished easily. Under the microscope it Jasper varieties found in the deposit is homogenous, fine-grained and shows an un­ Varieties found in the jasper deposit at Swierki oriented texture. Occasionally it contains minor are cherry-red, red-grey, brick-red, creamy-green dolomite amounts in the form of veinlets or rhom- and green. They all have streaky hematite concen­ bohedral individuals. Small opal concentrations are trations visible in hand specimens. The individual also present. In this variety the quartz content is colour varieties form streaks or nest-like concentra­ 77,89% by weight (Table 1). Chemical results reveal tions imparting an attractive colour pattern to the the presence of 0.002% copper which is likely to be entire rock mass. The most common are red-grey responsible for the green colouring. Rare mica jaspers while the green ones belong to the rarest and scales and iron in the form of minute goethite most prized varieties. pigment have also been identified under the micro­ The red-grey jasper is dense and can be easily scope. polished. Under the microscope it reveals a parallel, fluidal or unoriented texture. Its main chemical X-ray analysis constituent is silica (Table 1) reaching up to 77% by X-ray data were obtained from TUR 61 equip­ weight and usually developed as chalcedony, usually ment within 0-25° range, with filtered CoKa radia­ fine-grained. Locally it is accompanied by spheruli- tion, goniometer and recorder speeds being 27min. tic or fibrous forms. The rock also contains opal and and 600mm/h respectively. quartz sometimes filling fissures and voids. The X-ray data (Figure 3) reveal that both colour quartz is very often idiomorphic and then forms varieties differ only slightly in their chemical com­ druses. All the constituents described above are position. In the X-ray diffraction patterns quartz unevenly scattered throughout the rock. reflections predominate for dhki = 4,25, 3,34, 2,45, A constituent second in quantity is dolomite 2,28, 2,24 and 2,13 Â. Also, as evidenced by occurring in single rhombohedrons or filling fis­ reflections for dhW = 2,57 and 2,39 À, minor

Table 1: Chemical composition (average) of jaspers from Swierki near Nowa Ruda in % by weight. Red-grey jasper Green jasper

Fe203 0.59 1.85 Si02 77.79 77.89 Ti02 0.12 0.34 CaO 4.15 0.43 MgO 3.29 2.05 A1203 4.44 8.96 Na20 0.28 0.34 K20 1.95 3.48 + H20 0.39 1.97 H20 0.34 1.19 Loss of mass 7.01 3.63 Total 100.35 101.86 358358 ].J. Gemm.,Gemm., 1993,23,61993, 23, 6

1

2

Fig.Fig. 33.. X-raX-rayy diffractographdiffractographss ofof jaspersjaspers:: I.1. red-greyred-grey;; 22.. green.green.

FigFig.. 44.. DTDTAA curvecurvess ooff cherry-red-greycherry-red-grey jasper.jasper. tenoritetenorite amountamountss mamayy bbee presentpresent.. ThThee X-rayX-ray dif­dif­ fraction patternpatternss foforr bothboth colourecolouredd varietiesvarieties showshow anan ~ ______--..,...... ,DTG elevateelevatedd backgrounbackgroundd withiwithinn ththee 5-105-10 AÂ intervainterval l duedue toto thethe presencpresencee ooff poorlpoorlyy ordereorderedd opalopal silica.silica. TheThe occurrencoccurrencee ooff poorlpoorlyy crystallizecrystallizedd mixed-layemixed-layerr alu­alu- minosilicatesminosilicates cannocannott bbee excluded.excluded.

ThermaThermall analysisanalysis ThThee thermalthermal analysianalysiss wawass conductedconducted withiwithinn thethe 20-1000°20-1000°CC rangrangee usinusingg a Hungarian-madeHungarian-made derivato­derivato- graphgraph,, withwith 500mg500mg samplessamples anandd sensitivitiessensitivities DTGDTG 1/3,1/3, DTDTAA 1/31/3 anandd TGTG 100100.. ThermaThermall datdataa (Figur(Figuree 44)) confirmedconfirmed thethe presencepresence ,...---IDTA ooff mineralmineralss identifiedidentified previouslypreviously.. TheThe DTDTAA curvecurve showsshows a weakweak endothermaendothermall effeceffectt atat abouaboutt 570°C570°C relaterelatedd ttoo polymorphipolymorphicc quartzquartz transformationtransformation.. TheThe approximatapproximatee 33%% weighweightt lossloss ooff ththee samplesample iiss duedue toto dolomitedolomite dissociatiodissociationn aass confirmedconfirmed bbyy twtwoo en­en­ fOO 300 jO~ 700 dothermaldothermal effectseffects onon thethe DTADTA curvecurve atat 787800 andand 800°C800°C respectively.respectively. J.J. Gemm.Gemm.,, 1993,1993, 2323,, 6 353599

1:: .~ -i::: ~ ~ \I) -<:> ~ Q

j I------r---r-----r---Q..------rQ---,------.----.--Q.~ lBOO 1600 11,00 1200 fOOD BOO 700 600 500

Fig.s.Fig. 5. IRIR absorptioabsorptionn curvecurve ooff cherry-red-grecherry-red-greyy jasperjasper:: D-dolomiteD-dolomite;; Q-silicQ-silicaa (quart(quartzz andand chalcedony).chalcedony).

IRIR spectrophotometricspectrophotometric analysisanalysis SummarySummary FoForr IRIR spectrophotometricspectrophotometric determinationsdeterminations withwith­­ ExaminationExaminationss discussediscussedd abovabovee revealerevealedd thatthat jasjas­­ -1 inin ththee 400-1800cm -I rangrangee tabletizetabletizedd samplessamples witwithh perperss fromfrom Swierki,Swierki, LoweLowerr SilesiaSilesia areare builtbuilt chieflychiefly ooff KBrKBr werweree used.used. silicasilica developedevelopedd aass chalcedonychalcedony andand accompaniedaccompanied byby IRIR spectrophotometricspectrophotometric datdataa (Figure(Figure 5)5) forfor ththee minominorr amountamountss ooff opaopall andand quartz.quartz. TheThe rocrockk alsalsoo jasperjasperss examineexaminedd poinpointt toto ththee presencpresencee ofof smalsmalll containcontainss dolomite,dolomite, hematite,hematite, aluminosilicatesaluminosilicates anandd amountamountss ooff waterwater witwithh vibrationvibrationss aroundaround tractracee amountamountss ooff coppercopper mineralsminerals.. GeneticallyGenetically ththee 1l 1650cm-1650cm .. InIn additionaddition,, ththee absorptionabsorption curvcurvee showshowss jasperjasperss araree connecteconnectedd withwith low-temperaturelow-temperature silicisilici­- maximamaxima distinctivedistinctive ofof quartzquartz (Q)(Q) anandd ooff dolomitedolomite ficationfication ofof shalyshaly sedimentssediments byby fluidsfluids migrating migrating fromfrom (D).(D). VibrationsVibrations arounaroundd 1l00cm-1100cm"1 confirmconfirm ththee ththee underlyingunderlying melaphyres.melaphyres. MosMostt probablprobablyy silicisilici­- presencpresencee ooff opalopal.. A smallsmall aluminosilicatesaluminosilicates admixadmix­­ ficationfication wawass accompanieaccompaniedd bbyy simultaneoussimultaneous hematihemati­- turturee iiss indicateindicatedd bbyy vibrationvibrationss withiwithinn thethe 580580-- tization,tization, whilwhilee ththee crystallizatiocrystallizationn ofof dolomitdolomitee anandd -1 600cm -I rangerange.. minorminor quartquartzz amountsamounts occurredoccurred afteafterr silicification.silicification. J. Gemm., 1993, 23, 6 360

Test Report on the Hanneman Mini-cube II Peter G. Read, C.Eng., MIEE, EGA, DGA. Bournemouth

The benefits gained by the immersion inspec­ tion of gemstones have been well documented1 . To summarize, when a gem is immersed in a liquid whose refractive index is close to that of the gem, surface reflections are much reduced and light is able to penetrate the stone and reveal inter­ nal features. Immersion also helps in the identification of composite stones, as the differing refractive indices of the component parts of, for it _ i "TT example, a garnet topped doublet will show con­ trasting outlines.

Fig. 2. Versions of the Mini-cube II designed for specific Mag-lite flashlamps. In the basic model, a black plastic mounting ring is fitted which has a 13mm diameter hole for a standard pen torch (the hole can be enlarged for other light sources) the production of inexpensive gemmological test equipment, has produced the Mini-cube II. This instrument consists of a small glass cell with a screw top, a block of acrylic plastic milled out to take both the diameter of the cell and any suitable light source (e.g. a pen torch - see Figure 2). The milled surface of the plastic cell holder is left Fig. 1. Diffusion-treated Sri Lankan sapphire showing the spider-web effect produced by the concentration of colour at the facet unpolished and acts as a diffuser for the light edges source.

Fig. 3. The immersion cell, illuminated from the rear by a pen torch While in Sri Lanka in 1980,1 was shown a sap­ fitted in the plastic mount, contains a sapphire immersed in phire which had come under suspicion because of di-iodomethane (the copper wire ring is to prevent its unusual evenness of colour. When immersed in discoloration of the liquid) water the colour concentration along the faceted edge became apparent (Figure 1), revealing the stone as one of the early diffusion-treated corun- dums. This effect, sometimes referred to as a spider-web, is made more obvious if the stone is immersed in a high-RI contact fluid such as di- iodomethane (methylene iodide). With the increased production of diffusion- treated sapphires2, immersion inspection has become one of several important screening methods in the detection of these stones. To meet this requirement, W.W. Hanneman, a pioneer in

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm, 1993, 23, 6 361

have been immersed for evaluation purposes, this time using baby oil as an alternative to the less pleasant high RI liquids (a concept introduced by A. Hodgkinson). When used in conjunction with a pen torch and a 10X hand lens, the Mini-cube II forms a useful portable means of immersion inspection of quite sizeable gems (the cell neck diameter is 16mm) and immersion liquids can be safely left in the cell without danger of leakage. The Mini-cube II is marketed by Hanneman Gemological Instruments Fig. 4. Pieces of faceting-grade rough gem material being evaluated of PO Box 2453, Castro Valley, CA 94546, USA. while immersed in baby oil References Figure 3 shows a horizontally positioned mini- cube containing a sapphire immersed in 1. Read, P.G., 1990. Reflections on reflectivity. Journal of di-iodomethane. The coil of copper wire is pro­ Gemmology, 22, 2, 97-102. vided to prevent darkening of the immersion 2. Koivula, J.I., et al., 1992. Gem news - Update on diffusion- liquid. In Figure 4, several pieces of faceting rough treated sapphires. Gems & Gemology, 28, 1, 62-3. 362 J. Gemm., 1993, 23, 6

Notes from Tucson '93 Eric C. Emms, B.Sc., EGA, DGA Gemmological Association and Gem Testing Laboratory of Great Britain, London

Each year some 20,000 gemstone enthusiasts gemstones recently seen in the Laboratory. from around the world congregate in the city of The topic of gemstone treatments was much Tucson, Arizona, in the south west of the United discussed at the GemFair, especially diffusion States. Starting in the mid-1950s with a small treated sapphires, the prevalence and durability of group of Tucson mineral dealers exhibiting their fracture filling of emeralds and how these treat­ stock, the Tucson Gem Show is now not one but ments should be explained and described to the twenty different shows of varying size located at consumer. different hotel sites scattered around the city. The The shows appeared well attended and although first fortnight of February is designated 'Tucson some exhibitors were disappointed with the busi­ Gem and Mineral Days'. ness conducted, others reported good sales. I was Each show is organized by a different commit­ impressed with the quantity, quality and popular­ tee catering in the main for a particular market - ity of tourmalines on display, especially the red for example fossil and mineral dealers would variety. The Paraiba tourmalines in a wide range choose to exhibit at one show, while gemstone of colours were more in evidence than I expected, merchants would be attracted to another show. At accompanied by the similar colours of apatite. the busy budget motels strung along a road close Tanzanite in strong to deep saturation and large to the freeway, individual dealers, specializing in sizes (over lOct) was abundant, as were good- one type of gemstone, occupied the small bed­ coloured peridot from the US and Burma. Peridot rooms where they lived, slept, exhibited and dealt. from China and Kenya was also in evidence. A Hungarian would be dealing in East European The large number of red spinels from Burma minerals in one room, next door an Afghan would impressed, at attractive prices in comparison to be selling his lapis lazuli, whilst a dealer showing fine coloured Burma rubies on display. Pinkish- his Baltic and Dominican amber would be in the red Vietnamese rubies were for sale, one certified next room. Such is the scale of the event that a at over 8ct, although most dealers I spoke to indi­ visitor cannot hope to see and take in all that is on cated that Burmese material is currently easier to offer at Tucson. obtain than stones from Vietnam. The GAGTL decided to return to Tucson by It was interesting to learn more of the present exhibiting at the American Gem Trade state of the mining of Montana sapphires and to Association (AGTA) GemFair - the prestigious see recent production of unheated and heat- coloured stone show housed in the modern, spa­ treated stones. Three sources in the state are said cious Convention Center. Our aim was to to be producing small, flat crystals in many promote our overseas membership and market our colours. The stones I saw had a light saturation of ever popular Diploma in Gemmology leading to blue and were of good clarity. With large reserves the FGA. It was gratifying to learn from American rumoured to exist, the future for this native US gemmologists that the FGA is considered the pin­ gem looks encouraging. nacle of gemmological education and that many Turning to synthetic stones, I was struck by the Graduate Gemmologists wish to continue their absence of anything new and exciting at the studies by taking the FGA. The Gem Diamond shows. Coloured cubic zirconia continues to be Diploma leading to the DGA aroused interest, popular, with much rough in various colours being particularly in gemmologists from Canada and abundant. I was able to secure examples of recent South East Asia. The Gem Testing Laboratory US production of flux grown rubies and sapphires. was highlighted by an illustrated talk I gave on Current Moscow production of flux grown syn-

© Copyright the Gemmological Association ISSN: 0022-1252 J. Gemm, 1993, 23, 6 363

thetic spinel, synthetic opal and green GGG, Unusual quartzes included cabochon-cut trans­ together with Russian hydrothermal synthetic parent pink quartz (not to be confused with rose emerald, were obtained. quartz) and crystals of ametrine (quartz with Garnet was the theme of the Tucson Gem and purple, colourless and brown colour zones), reput­ Mineral Show. Here nomenclature of the six gem edly from Bolivia, characterized by the garnets was well explained and illustrated by rhombohedral faces meeting at the basal pinacoid. exhibitors displaying large crystal specimens of GAGTL is committed to expanding the oppor­ each species; large uvarovite crystals from Finland, tunities for home and overseas students to study orange spessartine garnets from Namibia and iri­ our FGA and DGA courses, and each year more descent andradite from a new source in Mexico of our Allied Teaching Centres are established for were particularly striking. A twenty kilogramme this purpose. The Tucson gem shows provide the example of Libyan glass (the natural silica glass opportunity to discuss with our overseas friends found in North Africa) and the Thompson dia­ matters of interest and mutual concern, to empha­ monds (three pear-shaped brown diamonds cut size our educational plans and to clarify from a 264ct rough stone) attracted the eye. perceptions of our future strategy.

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TELEPHONE: (071) 404 3334 FAX: (071) 404 8843 364 J. Gemm., 1993, 23, 6

Gemmological Abstracts

ASHBAUGH III, C.E., 1992. Gamma-ray BlANCHI POTENZA, B., DE MICHELE, V., spectroscopy to measure radioactivity in LOBORIO, G., Rizzo, R., 1991. Le olivine gemstones. Gems & Gemology, 28, 2, 104- délia Sardegna: un materiale di intéresse 111, 8 figs. gemmologico. La gemmologica, 16, 1, 17-28, Gamma-ray spectroscopy to determine the 13 photos in colour, 2 figs, 1 map. radionuclides used to colour a yellow-green Green transparent olivines from Sardinian diamond (bought as radium-treated) and a deep alkali basalts have gem potential. All major blue topaz. The diamond had been treated with properties are described with a note on their americium-241, a product of bombarded occurrence. The basalts are of Plio- Pleistocene uranium-238 which coloured the surface and left age and occur near Pozzomaggiore, Sassari, radio-activity which would decline to a legally Sardinia. M.O'D. acceptable level for sale in rather more than three thousand years [not a very sound BLANKENBURG, H.-J., LOTTNER, S., 1991. commercial proposition!]. The (London blue) Achate aus einem temporären topaz is a better bet and should reach a safe level Ignimbritaufschluss bei Chemnitz. in about two years. [Tests for radionuclides Aufschlüsse 42, 275-383, 7 photos (5 in obviously call for expensive equipment and the colour), 3 figs. ethics and sense of such treatment are highly Agate is found in a disintegrated ignimbrite questionable]. The author gives the half life of near Chemnitz, Germany. M.O'D. cobalt-60 gamma-ray signatures as 5.27 years and europeum-152 as 13.5 years (both have BLANKENSHIP, D., 1992. The color of jade. been used to colour diamonds), and says that it Bulletin of the Friends of Jade, 7, 48-55. would take decades for even these fast faders to The cause of colour in both nephrite and decline to a point where they were undetectable. jadeite is reviewed; several areas where jade is Not all radiation, however, leaves such found are covered. M.O'D. prolonged radio-active signatures. R.K.M. BLANKENSHIP, D., 1992. Two stones. Bulletin of BANK, H., 1991. In Partien natürlicher the Friends of Jade, 7, 24-8. Rohedelsteine synthetische Rohsteine A short review of the two jade minerals with beobachtet. (Synthetic rough found in natural notes on some of their commoner imitations. rough gemstone lots.) Zeitschrift der Deutschen M.O'D Gemmologischen Gesellschaft, 40, 4, 253-5, bibl. BODE, R., KLAUS, D., 1992. Neue The author enumerates a number of instances Rhodochrosit-Funde in der Sweet Home where synthetics have been found amongst Mine bei Alma/Colorado. Mineralien Welt, 3, rough gem lots. In a lot of emeralds from 6, 43-5, 13 photos (12 in colour), 1 map. Zambia, Chatham emeralds were found, a lot Further production of rhodochrosite at the from Colombia contained glass, a lot from Sweet Home Mine, Alma, Colorado, USA, is Nigeria yellowish fluorites. Rubies contained reported. M.O'D. Verneuil products, alexandrite from Brazil some synthetic Russian alexandrite, glass CAMPBELL, I.C.C., 1992. A short note on the masqueraded as tourmaline and aquamarine as appearance of some inclusions seen in a well as amethyst which also contained some number of blue sapphires from Bo Ploi, synthetic amethyst. The author also warns of Thailand. South African Gemmologist, 6, 2, 24- quartzes which have been treated with green oil 5, 4 photos in colour. and sold as emeralds, and glass instead of Blue sapphires from Bo Ploi, Thailand, were diamond crystals. E.S. found to contain liquid feathers and possible plagioclase crystals as well as wool-like rutile J. Gemm., 1993, 23, 6 365

crystals and negative inclusions. The inclusions DlRLAM, D.M., MlSIOROWSKI, E.B., TOZER, distinguish the sapphires from their Burmese R., START, K.B., BASSETT, A.M., 1992. counterparts. M.O'D. Gem wealth of Tanzania. Gems & Gemology, 28, 2, 80-102, 27 figs. CASSEDANNE, J-P., ALVES, J-N., 1992. L'aigue Deals in some detail with diamond, Mwadui marine au Brésil (part 2). Revue de (formerly Williamson) Mine; ruby: Longido, gemmologie, 111, 11-14, 2 photos (1 in Umba River and Morogoro; sapphire: all colours colour). and change of colour, Umba River; zoisite: The second part of the paper discusses the Merelani Hills, the purplish blue tanzanite and classification and formation of pegmatites some yellow, reddish-brown and recently containing aquamarine. Simple, complex and transparent green zoisite from the same area; intermediate types are postulated and described. garnet, including malaia (reddish orange) from M.O'D. Umba valley; tsavorite from the Tsavo National park in Kenya and from several Tanzanian sites CASSEDANNE, J-P., ALVES, J-N., 1992. L'aigue including the Merelani Hills; rhodolite from marine au Brésil (part 2). Revue de many localities and colour-change pyrope/ gemmologie, 112, 7-11, 2 photos (1 in colour). spessartine (blue-green daylight and purple-red The paper describes prospecting for in incandescent light) from Umba, other colour aquamarine in the pegmatites of Brazil and changes also known and illustrated; tourmaline discusses pegmatite age and formation. M.O'D. in various types and many colours including the 'chrome' green now known to be due to COZAR, J.S., GARZON, J., 1992. Fluoruro de vanadium, from various northern and eastern magnesio sintetico, en esmeralda sintética sites including Umba; emerald from Lake hidrotermal rusa. Boletin del Instituto Many ara and Sumbawanga. Gemolôgico Espanol, 34, 70-2, 5 photos in Other gems listed are actinolite, alexandrite, colour. amblygonite, amethyst, andalusite, apatite, Tetragonal crystals of MgF2 have been found aquamarine, bronzite, chrysoberyl cat's-eye, in Russian hydrothermal emeralds. Energy- Chrysoprase, agates, etc., diopside, enstatite, dispersive X-rays are used to demonstrate their epidote, euclase, feldspar, fluorite, hypersthene, presence. M.O'D. idocrase, iolite, kornerupine, kyanite, malachite, pearls, peridot, phenakite, prase opal, quartz, COZAR, J.S., IBARRA, A., 1992. Centros de color rhodonite, scapolite, sillimanite, sinhalite, sphene, en espinelas. Boletin del Instituto Gemolôgico spinel, topaz, turquoise and zircon. Those Espanol, 34, 42-52, 8 figs (1 in colour), 5 italicized are dealt with briefly in this paper. photos in colour. Writers suggest that the considerable gem Defects and impurities in MgAl204 are potential could build to the great benefit of this discussed with reference to natural and synthetic impoverished country, but the health problem of stones. M.O'D. the spread of HIV virus and AIDS challenges that effort. R.K.M. CURTO MILA, C.j FABRE FORNAGUERA, J., 1992. Fluorite and associated minerals from DUCARRE, C-J., 1992. Gemmologie en Savoie Asturias, Spain. Mineralogical Record, 23, 1, (part 1). Revue de gemmologie, 111, 3-4, 1 69-76, 14 photos (12 in colour), 1 map. map, 4 figs. Some of the fluorites from a number of mines Mineralization of the French Savoy Alps is in Asturias, Spain, are of gem or ornamental discussed with particular reference to geological quality. Details of the geology, mineralogy and processes and mountain building. M.O'D. associated minerals are given. M.O'D. DUCARRE, C-J., 1992. Gemmologie en Savoie DE ALDECOA, M.A.I., SAPALSKI, C, 1992. (part 2). Revue de gemmologie, 112, 3-6, 3 Joyas espanolas en la historia: siglos XVII y photos in colour, 1 fig. XVIII. Boletin del Instituto Gemolôgico Espanol, Blue beryl, axinite, epidote and quartz from 34, 63-9, 13 photos in colour. the Savoy area of France are described. M.O'D. Spanish jewels of the 17th and 18th centuries are described, examples being taken from a FREY, R., 1992. Jade and science. Bulletin of the number of museums in Spain and abroad. Friends of Jade, 7, 56-69. M.O'D. The development of modern methods of gem 366 J. Gemm., 1993, 23, 6

testing is described with particular reference to found to contain a significant proportion of good the two jade minerals and their commoner paste, chalky-blue fluorescing, imitations with RI simulants. M.O'D. close to those of quartz (which did not fluoresce). FRITSCH, E., WU, S-T., MOSES, T., MCCLURE, A black natural pearl was found off the coast S.E., MOON, M., 1992. Identification of of Baja California (La Paz, Mexico, formerly bleached and polymer-impregnated jadeite. noted for such pearls, but not recently - the Gems & Gemology, 28, 3, 176-87, 14 figs. return of this type of oyster is obviously Jadeite, bleached of iron-staining and welcome); black dyed mabe blister pearls were impregnated with acrylic resin, possibly with proved by lifting colour with a swab of very weak added colour, to conceal cracks, is being offered nitric acid, LUV gave dull orange-red in quantity in Taiwan and Hong Kong as natural fluorescence, silver bromide was the colourant; coloured, RI and spectrum are right for jadeite, nine large 'Geneva rubies' (early flame-fusion S G rather low and most treated stones will float synthetics) were an unusual find for the NY lab; in 3.32 liquid, while most untreated stones sink. a sapphire with rubbed facet edges was a Heat probe melts or burns filler. A spot of diffusion treated stone which would lose colour hydrochloric acid on an untreated stone will if repolished - the heat process is thought to produce sweating near that spot. make the surface brittle and more prone to wear, Treated stones fluoresce faint bluish-white in successive heatings, which are common with this LUV, white areas of untreated stone fluoresce treatment could increase this tendency; curved yellow. Infrared spectrometry provides definitive striae in synthetic orange or yellow sapphires, test since acrylic filler gives sharp lines at normally difficult to see, can be made more 2900cm1 and in the near infrared. Bleached/filled obvious by using a blue filter on the microscope stones may fade. R.K.M. light. R.K.M.

FRYER, C.W., CROWNINGSHIELD, R., MOSES, FRYER, C.W., CROWNINGSHIELD, R., MOSES, T., HURWIT, K., KANE, R.E., 1992. Gem T., HURWTT, K., MCCLURE, S.F., 1992. Gem Trade lab notes. Gems & Gemology, 28, 2, trade Lab Notes. Gems & Gemology, 28, 3, 123-8, 19 figs. 192-7, 18 figs. A fracture-filled diamond damaged by Polymer-filled cavity in pavilion facet of mount-repair heat confirmed prediction that alexandrite described and illustrated; in up-date sooner or later someone would fall into this trap. of fracture filling in diamond new flash colours Diamonds without fillings may take repair heat are noted; 6.90ct diamond, fractured in cutting, but filled ones can suffer disastrously; this stone was filled but needed second and third treatment still had tell-tale 'flash-effect' even after it was before polishing was complete, then two hour damaged; filling material contains lead which is spell in ultra-sonic cleaner shattered and opaque to X- rays. removed most of the filling, leaving flaw A 22.28 carat stone was the largest example extremely visible; light pink diamond had of a chameleon type diamond (temporary ribbon-like etch features similar to laser holes change of colour on moderate heating) so far but entrances were square, not round like laser seen in the NY lab. A 'black5 diamond with good drilling, and had to be inherent to the stone polish proved to be an irradiated very dark green [transverse striation of holes also argues natural stone, polish too perfect for a natural black one, origin], stone graded 12 for lack of clarity. residual radio-activity would need some 36 years A pair of jadeite earclips splice-repaired, to reduce to US Nuclear Regulatory cement fluoresced under UV; cat's-eye yellow Commissions's low level requirement for legal opal had anomalous RIs of 1.45 and 1.47, X-ray sale. diffraction showed cristobalite with amorphous A 5.56 carat 'emerald' with 'jardin' background. inclusions was a green YAG synthetic, singly A shark pin made from an odd-shaped blister refractive off-the-scale RI and SG 4.55 should pearl was probably unbacked; large drop pearl have made the fraud obvious, 'jardin' was a mass was also hollow, filled with composite material; of bubbles; crown glass imitations of crystals another large hollow pearl was the body of a have been offered as 'healing stones' ['Crystal gold and diamond owl pendant-seal; a black healing' is a health fad probably with little basis mabe pearl had been dyed with silver nitrate and in fact]; a 'turquoise' with pitted surface was had a crystalline filling. shown to be glass; a parcel of amethysts was A three-row necklace of 'ruby' beads was low- J.J. Gemm.,Gemm., 1993,1993, 23,23, 66 367367

gradegrade sapphire,sapphire, crackle-dyedcrackle-dyed red,red, nono chromiumchromium der Deutschen Gemmologischen Gesellschaft, Gesellschaft, 41, 41 , absorption,absorption, bubutt sapphiresapphire bandbandss atat 450450 andan d 1,1, 17-19,17-19, 3 photomicrographs,photomicrographs, 1 table,table, bib!.bibl. 380nm380nm werewere seenseen andand anotheranother atat 560560 probablyprobably TheThe redred garnetsgarnets from MalawiMalawi (exact(exact locationlocation duedue toto dye;dye; a 125125 caratcarat greyish-greengreyish-green cabochoncabochon ooff occurrenceoccurrence notnot known)known) werewere shownshown toto bebe zircon,zircon, claimedclaimed toto bebe world'sworld's largest,largest, hahadd aa almandine-spessartine-pyrope-grossularalmandine-spessartine-pyrope-grossular mixedmixed superblysuperbly sharpsharp cat's-eyecat's-eye andand exceptionallyexceptionally strongstrong crystals.crystals. TheThe garnetsgarnets hadhad unusualunusual sphericalspherical absorptionabsorption spectrum.spectrum. R.K.M.R.K.M. aggregatesaggregates asas inclusionsinclusions inin thethe centrecentre ofof thethe crystal,crystal, whichwhich werewere identifiedidentified withwith thethe helphelp ofof aa GENDRON,GENDRON, F.,F., 1992.1992. 1492-19921492-1992 LesLes ElEl DoradosDorados scanningscanning electroelectronn microscopemicroscope asas quartzquartz andand gemmologiquesgemmologiques americains.américains. Revue dede ilmenite.ilmenite. E.SE.S.. gemmologie, 110,110 , 15-16.15-16 . MaterialsMaterials usedused forfor ornamentornament inin thethe AmericasAmericas HENN,HENN, U.,U., BANK,BANK, H.,H., 1991.1991. AussergewohnlicheAussergewöhnliche from thethe 16th16th centurycentury areare brieflybriefly discussed.discussed. SmaragdeSmaragde ausaus NigeriaNigeria.. ExceptionalExceptional emeraldsemeralds M.O'D.M.O'D. fromfrom Nigeria.Nigeria. ZeitschriftZeitschriJt der DeutschenDeutschen Gemmologischen GeselischaJt,Gesellschaft, 40,40, 4,4, 181-7,181-7, 11 GROAT,GROAT, L.A.,L.A., HAWfHORNE,HAWTHORNE, F.C.,F.C., ERCITERCIT,, T.S.,T.S., photophoto inin colour,colour, 4 photomicrographs,photomicrographs, 11 1992.1992. TheThe chemistrychemistry ofof vesuvianite.vesuvianite. graph,graph, bib!.bibl. Canadian mineralogist, 30, 30 , 19-48,19-48 ,23 23 figs. figs . TheThe emeraldemerald crystalscrystals fromfrom NigeriNigeriaa araree CrystalCrystal chemistrychemistry andand chemicalchemical variationsvariations iinn unusuallyunusually wellwell crystallized,crystallized, somesome examplesexamples beingbeing vesuvianitevesuvianite areare studiedstudied from 7676 samplessamples fromfrom 5544 crystallizedcrystallized atat bothboth ends.ends. RIRI 1.569-1.576,1.569-1.576, DDRR differentdifferent localities.localities. A proposedproposed generalgeneral formulaformula 0.005-0.006,0.005-0.006, SGSG 2.65-2.67.2.65-2.67. chromiumchromium contentcontent forfor boron-freeboron-free vesuvianitevesuvianite isis givengiven aass ofof 0.06-0.110.06-0.11 weightweight % Cr2203. TheThe greengreen colourcolour Xl9Yl3Z1S06SW10X19Y13Z18O68W10 wherewhere X areare cationscations occupyingoccupying isis causedcaused bbyy a broadbroad absorptionabsorption spectrumspectrum bandband [8]-[8]- co-ordinateco-ordinate sites,sites, YareY are cationscations occupyingoccupying ofof Cr'"'Cr3* asas wellwell asas Fe2+Fe2+ andand Fe><-.Fe3*. BesideBeside distinctdistinct [6]-[6]- andand [5]-[5]- co-ordinateco-ordinate sites,sites, Z areare cationscations growthgrowth zoningzoning twotwo andand threethree phasephase inclusionsinclusions occupyingoccupying [4]-[4]- co-ordinateco-ordinate sitessites andand WareW are havehave beenbeen observed,observed, thethe latterlatter similarsimilar toto thosethose iinn monovalentmonovalent andand divalentdivalent anions.anions. M.O'D.M.O'D. ColombianColombian emeralds.emeralds. E.SE.S..

GOBELIN,GÜBELIN, E.,E., 1992.1992. DansDans lala valleevallée desdes rubis.rubis. HENN,HENN, U.,U., BANK,BANK, H.,H., 1992.1992. OberÜber diedie Revue de gemmologie, 111,111 ,5-8, 5-8 , 44 photos photos (2(2 in in EigenschaftenEigenschaften vonvon imim FlussmittelverfahrenFlussmittelverfahren colour).colour). hergestelltenhergestellten synthetischensynthetischen rotenroten undund blauenblauen MiningMining operationsoperations inin thethe MogokMogok regioregionn ooff SpinellenSpinellen ausaus Russland.Russland. (About(About thethe propertiesproperties MyanmarMyanmar andand detailsdetails ofof rubiesrubies areare discussed.discussed. ofof flux-grownflux-grown syntheticsynthetic redred andand blubluee spinelsspinels M.O'D.M.O'D. fromfrom Russia.)Russia.) ZeitschriJtZeitschrift der DeutschenDeutschen Gemmologischen GesellschaJt,Gesellschaft, 41,41, 1,1, 1-6,1-6, 88 GOBELIN,GÜBELIN, E.,E., 1992.1992. GreeGreenn zoisite.zoisite. (Letter).(Letter). photomicrographsphotomicrographs,, 1 table,table, 1 graph,graph, bib!.bibl. Gems & Gemology, 28,28 , 2,140.2, 140. TheThe valuesvalues forfor RIRI areare 1.1.716-1.71 716-1. 7199 andand SGSG == AnAn objectienobjection toto thethe useuse ofof thethe namename 'green'green 3.58-3.62,3.58-3.62, wellwell withinwithin thethe limitslimits ofof naturalnatural tanzanite'tanzanite' forfor thethe facetablefacetable greengreen zoisite,zoisite, magnesiummagnesium spinels.spinels. TheThe colourcolour isis causedcaused inin thethe reportedreported inin thethe SpringSpring issueissue ofof TheThe Journal,Journal, redred stonesstones byby Cr'"',Cr3*, inin thethe blueblue byby C02+Co2+ whichwhich cancan rightlyrightly pointpointss outout thatthat thethe TiffanyTiffany namename bebe seenseen inin thethe spectra.spectra. MicroscopicMicroscopic studiesstudies showshow 'tanzanite''tanzanite' belongsbelongs exclusivelyexclusively toto thethe blubluee zoisite,zoisite, growthgrowth lineslines andand tabbytabby extinctionextinction asas wellwell asas fluxflux andand 'green'green tanzanite'tanzanite' isis a horriblehorrible confusionconfusion ooff residuesresidues ofof differentdifferent typestypes andand arrangements,arrangements, names.names. 'Green'Green zoisite'zoisite' isis sufficient.sufficient. R.K.M.R.K.M. somesome beingbeing ofof metallicmetallic origin,origin, somesome beinbeingg similarsimilar toto thethe LechtleitnerLechtleitner andand somesome producingproducing two­two- HANNI,HÄNNI, H.A.,H.A., 1992.1992. IdentificationIdentification desdes fissuresfissures phasephase inclusions.inclusions. E.SE.S.. traitees.traitées. Revue de gemmologie, 110,110, 10-12,10-12, 4 photophotoss inin colour.colour. HENN,HENN, U.,U., BANK,BANK, H.,1992.H.,1992. KlarKlar durchsichtiger,durchsichtiger, FilledFilled fissures inin emeraldsemeralds cancan bbee detecteddetected byby roterroter LabradoritLabradorit ausaus Oregon,Oregon, USA.USA. (Clear(Clear a varietyvariety ofof teststests whichwhich areare summarizedsummarized andand transparenttransparent redred labradoritelabradorite fromfrom Oregon,Oregon, illustrated.illustrated. [Translated[Translated from thethe English]English].. USA.)USA.) ZeitschriJtZeitschrift der DeutschenDeutschen M.O'D.M.O'D. Gemmolo/!ischenGemmologischen Gesellschaft, 41,41, 1,1, 49-51,49-51, 11 368 J. Gemm., 1993, 23, 6

yellow, or yellow-red to reddish-brown and red. Beers/Republic of Sakha (Yakutia) sales RII n0 =1.558, n2= 1.563, ny= 1.555, DR 0.008. agreement; R.E. Kane's visit to alluvial diamond SG 2.70. The chemical composition is 50.5% mines at Longlands, SA; agreement on anorthite, 46.5% albite, 3% orthoclase. The prospecting and mining between De Beers and deep red colour is caused by Fe, absorption Tanzania; Zaire output reduced by a third, band at 565nm. E.S. regulations tightened to reduce smuggling.

HENN, U., REDMANN, M., 1991. Geschliffener, Coloured Stones klar durchsichtiger, farbloser Katapleit von Californian exhibit of exotic beetles showed Mont Saint Hilaire, Kanada. (Cut 107 different iridescent species which may be transparent colourless katapleite from Mount used in jewellery in one part of the world or St. Hilaire, Canada.) Zeitschrift der Deutschen another; cat's-eye golden beryl, possibly Gemmologischen Gesellschaft, 40, 4, 197-200, 1 irradiated, is illustrated; a Cairo museum photo under crossed niçois, 2 tables, bibl. exhibits garnet-set Greco-Roman jewellery; Katapleite is a hydrous sodium zirconium largest jadeite boulder weighing estimated 33 silicate which under normal temperatures tonnes is displayed outside Myanmar Gems crystallizes monoclinically and at 139°C Enterprise in Yangon (Rangoon); further reports hexagonally, Hardness 6, perfect cleavage; if on Vietnam rubies; iron nickel meteorite is calcium rich the colour is light yellow to brown, sliced, etched and mounted as jewellery; black otherwise colourless to bluish. SG 2.72. RI mabe 'pearls' made from nautilus shell are again 1.590-1.629, DR 0.039. Has an oily appearance on offer; a visit to Mont St Hilaire quarry, near under the microscope and shows irregular Montreal, for red-brown villiaumite, carletonite, interference under crossed niçois. E.S. hackmanite, natrolite, sphalerite, catapleiites, orange serandites, albites, pectolites, burbankite, HYRS, I.J., 1992. Die Mineralien der Alpin- shortite, cryolite, and colourless vesuvianite Paragenese aus dem Nordural/Russlang. [idocrase]; Tajikistan, (Pamirs), now Mineralien Welt, 3, 6, 59-62, 8 photos in independent, is to develop gem potential, colour, l map. including fine marble, spinel and lapis lazuli. Minerals from Pripoljarnyi in the Urals include gem quality sphene and axinite as well as Enhancements large specimens of phantom quartz. M.O'D. Acrylic spray coating for stones which do not take a good shine results in unnatural glassiness KANE, R.E., KAMMERLING, R.C., 1992. Status especially in recessed carving, coatings can be of ruby and sapphire mining in the Mogok scraped off or dissolved by acetone; massive stone tract. Gems & Gemology, 28, 3, 152-74, beryl/quartz is being heat-quench dyed to 26 figs. resemble charoite, sugilite, turquoise or coral, A well illustrated account of this important dye concentrated in surface fissures easily seen; source of gem corundum, dealing with history, aquamarine and other beads enhanced by dyeing geology, geographic location, nationalization, the string and the stringing hole and by heat- mining techniques (twinlons {narrow pits}, quench dyeing; a 'concrete' Andamooka hmyawdwins {trenches}, loodwins {cavities in sandstone opal is blacked by sugar/acid marble}), mechanisation including tunnelling, treatment and then toughened with a plastic; recovery, central crushing plant, production, silver nitrate, smoke and black plastic have also manufacture and distribution, and other ruby been used to give a black ground to porous opal; occurrences in Myanmar. A valuable paper. a local preference in Egypt for greenish R.K.M. turquoise is met by oiling the blue material to the required colour. KOIVULA, J.I., KAMMERLING, R.C., FRITSCH, E., 1992. Gem news. Gems & Gemology, 28, Synthetics and Simulants 2, 129-39, 17 figs. Another sawn and hollowed beryl crystal (from Bogota) filled with green liquid and Diamonds cemented together again, was detected when a Reports on diamond-claim rush at Lac de cutter tried to saw it and it bled green; more Gras in Canada's Northwest Territories; a information on Russian opaque CZ gives RIs diamond technical symposium in Israel; about 2.14 to 2.165; bicolour red CZ is diamond bearing kimberlite pipes in Ukraine; described and illustrated; many glass imitations small industrials near Tashkent; De of Paraiba tourmaline crystals have been JJ.. Gemm.,Gemm., 1993,1993, 23,23, 6 363699

encounteredencountered,, ononee frofromm BogotaBogota isis illustrated;illustrated; culturedcultured pearpearll reportedreported earlierearlier isis nownow illustrated;illustrated; VietnameseVietnamese parcelparcelss ofof blueblue sapphiresapphire rougroughh havehave VenezuelaVenezuelann investigationinvestigationss towardtowardss pearlpearl beebeenn foundfound ttoo contaicontainn largelarge crystalcrystalss ooff blueblue cultivationcultivation havehave begunbegun,, usinusingg goodgood nacrenacre spinel,spinel, andand parcelparcelss ofof rubyruby roughrough continucontinuee ttoo bebe producinproducingg P. radiata oysters.oysters. foundfound withwith significantsignificant admixtureadmixturess ooff 'water­'water- LongidLongidoo rubrubyy from TanzaniTanzaniaa usuallusuallyy suitablesuitable worn'worn' VerneuilVerneuil synthetics,synthetics, immersionimmersion testtestss areare onlyonly forfor cabochons,cabochons, bubutt a smallsmall deedeepp reredd facetedfaceted essentiaessentiall forfor botbothh roughrough anandd cutcut parcels;parcels; brillianbrilliantt isis illustrated,illustrated, aboutabout 6 caratcaratss ofof suchsuch syntheticsynthetic sodalitesodalite waswas amongamong severalseveral syntheticssynthetics stonesstones maymay bbee expecteexpectedd from 2020 tontonss ooff roughrough;; from AcademiaAcademia SinicaSinica (China),(China), this isis colourlesscolourless lankaroka,Iankaroka, Madagascar,Madagascar, iiss producinproducingg parti­parti­ bubutt irradiateirradiatess ttoo a googoodd blueblue.. colourecolouredd sapphiressapphires inin palpalee blubluee andand orange­orange- brown,brown, somesome ooff themthem magnetic;magnetic; smallsmall crystalcrystalss ofof Instrumentation greegreenn sphaleritesphalerite [blende][blende] werewere foundfound inin HannemaHannemann GemologicaGemologicall InstrumentsInstruments areare Pennsylvania;Pennsylvania; a greegreenn tourmalintourmalinee fromfrom ParaibaParaiba offerinofferingg a cheapercheaper simulantsimulant ooff ththee expensiveexpensive hadhad a cascadcascadee ofof metallicmetallic yellowyellow inclusions.inclusions. quartquartzz wedgewedge usedused toto determinedetermine optiopticc signsign inin microscopicmicroscopic workwork.. RK.M.R.K.M. Enhancements LargeLarge ThaiThai parcelparcelss ofof 'natural'natural coloured'coloured' KorVULA,KOIVULA, J.I.J.I.,, KAMMERLINGKAMMERLING,, RC.,R.C., FRITSCH,FRITSCH, cabochocabochonn sapphiressapphires araree beinbeingg saltedsalted withwith E.E.,, 1992.1992. GemGem newsnews.. Gems & Gemology, 2828,, diffusiondiffusion treatedtreated stones;stones; aatt TucsoTucsonn a kikitt waswas 3,3, 198-209,198-209, 2222 figs. offeredoffered forfor fracture-fillingfracture-filling emeraldemeraldss withwith greengreen dye;dye; updateupdate onon crackle-dyecrackle-dyedd emerald-greenemerald-green Diamonds quartzquartz reportsreports theythey areare convincingconvincing table-utable-upp butbut NeNeww extractioextractionn planplantt nearnear AlexandeAlexanderr BayBay,, S.S. crackcrackss easeasyy ttoo seesee base-upbase-up overover whitwhitee card,card, testtest Africa,Africa, operatesoperates oonn sea-water;sea-water; atat LacLac dede Gras,Gras, asas quartz,quartz, dydyee thoughthoughtt ttoo bbee greengreen OpticonOpticon Canada,Canada, a 160160 tonton samplesample ofof oreore yieldeyieldedd 101101 whichwhich givesgives absorptionabsorption fromfrom 660-690nm,660-690nm, nono caratcaratss ofof diamonddiamond,, 2525 peperr cencentt gegemm quality;quality; chromiumchromium lines;lines; a rubrubyy crystacrystall wawass coatedcoated withwith BritishBritish CrowCrownn Jewels,Jewels, includinincludingg CullinaCullinann I [and[and amorphousamorphous redred spinel,spinel, SGSG aboutabout 3.753.75,, strongstrong II]II] andand Koh-i-NooKoh-i-Noorr diamonds,diamonds, araree ttoo bbee broughtbrought reredd luminescencluminescencee inin UV,UV, RRII anandd spectrumspectrum uupp ttoo groundground floorfloor levelevell inin thethe TowerTower ooff LondonLondon [surprisingly][surprisingly] typicaltypical ofof corundum.corundum. iinn 1994;1994; IndiaIndia isis ttoo increaseincrease diamondiamondd mininminingg inin collaboratiocollaborationn witwithh AustraliaAustralia;; miningmining atat Synthetics and SimulantsSimulants Jwangeng,Jwangeng, Botswana,Botswana, iiss ttoo expandexpand;; alluvialalluvial A newnew Czochralski-pulledCzochralski-pulled 'alexandrite''alexandrite' isis diamonddiamondss foundfound nearnear MomeikMomeik andand Theindaw,Theindaw, marketemarketedd aass Allexite,Allexite, colour-changecolour-change bluish-greenbluish-green Myanmar,Myanmar, areare beinbeingg cucutt inin YangonYangon;; VenetiaVeneria ttoo reddish-purplreddish-purplee similarsimilar ttoo finfinee BrazilianBrazilian minemine,, NN.. TransvaalTransvaal,, isis operatinoperatingg andand forecastsforecasts 5 alexandritealexandrite,, curvecurvedd striaestriae seen,seen, RRII 1.740-1.749,1.740-1.749, milliomillionn caratscarats ofof rougroughh a year;year; BelgiaBelgiann ownedowned SGS G 3.72,3.72, redred luminescenceluminescence veryvery marked;marked; greengreen HaHaii DuonDuongg diamonddiamond factoryfactory,, VietnamVietnam,, isis glasglasss mademade from fusedfused rockrock from MMtt StSt HelensHelens polishinpolishingg ready-sawready-sawnn rougroughh forfor returreturnn toto witwithh addeaddedd colorantcolorantss isis stillstill beinbeingg offered;offered; AntwerpAntwerp.. scratchedscratched assembleassembledd stonestone lookedlooked likelike badlybadly orientedoriented alexandrite,alexandrite, hahadd reredd centrcentree encloseenclosedd bbyy Coloured StonesStones greegreenn glassglass;; flame-fusionflame-fusion synthetisyntheticc rubies,rubies, AnAn amberamber iiss illustrateillustratedd witwithh 'insect'insect inclusion'inclusion' offeredoffered aass naturalnatural stonesstones atat MaMaee SotSot onon thethe engravedengraved onon ititss basebase;; RussianRussianss marketingmarketing heat­heat- Thai/BurmThailBurmaa borderborder,, havhavee beenbeen quench-fracturedquench-fractured improvedimproved BaltiBalticc ambeamberr iinn HongHong Kong;Kong; 'Glory'Glory andand crudelycrudely cutcut toto aidaid deception;deception; anan imitationimitation BlueBlue'' chalcedonchalcedonyy iiss reportedreported fromfrom MontanaMontana;; a opalopal withwith mouldedmoulded plasticplastic 'faceted''faceted' crown,crown, MadagascanMadagascan crystalcrystal hahadd a corunducorundumm centrecentre backebackedd bbyy patternepatternedd diffractiodiffractionn foifoill wawass offeredoffered coveredcovered concentricallconcentricallyy withwith greengreen spinelspinel andand atat recenrecentt gegemm show;show; aboutabout 100100 specimensspecimens werewere blubluee sapphirine;sapphirine; greegreenn crystalscrystals frofromm MerelaniMerelani seenseen inin GermanGermanyy ooff a compositcompositee crystalcrystal Hills,Hills, homehome ofof tanzanittanzanitee anandd greengreen zoisitezoisite,, werewere consistingconsisting ofof a zonedzoned tourmalinetourmaline sliceslice cementedcemented chromchromee diopsidediopside;; opalizedopalized iron-stoniron-stonee iiss beingbeing toto colouredcoloured glass.glass. RK.M.R.K.M. useusedd foforr carvingscarvings;; anan egeggg ooff rarraree mansfieldite,mansfieldite, a newnew ornamentaornamentall rocrockk from Algeria,Algeria, hahass beenbeen cutcut KUMARATILAKE,KUMARATILAKE, W.L.D.R.A.W.L.D.R.A.,, RANASINGHE,RANASINGHE, iinn Germany,Germany, looklookss likelike variscite.variscite. U.N.,U.N., 1992.1992. UnusualUnusual corunducorundumm bearinbearingg gemgem PearlPearl shellshell isis reportereportedd frofromm BajaBaja,, California;California; pocketspockets atat AvissawellaAvissawella anandd Getahetta,Getahetta, SriSri alsoalso pearlpearlss fromfrom a SpanishSpanish galleongalleon,, badlybadly LankaLanka.. ZeitschriftZeitschriJt der DeutschenDeutschen damageddamaged byby lonlongg immersion;immersion; a liquid-filledliquid-filled Gemmologischen GesellschaJt,Gesellschaft^ 4141,, 1,1, 7-167-16.. 2 370370 J.J. Gemm.Gemm.,, 1993,1993, 23,23, 6

mapsmaps,, 2 photos,photos, 4 diagrams,diagrams, bibl.bibl. TakovajTakovajaa imim Ural.Ural. Mineralien Welt, 3,3, 6,6, 6868-- ForFor ththee lastlast foufourr decadesdecades peculiarpeculiar kindskinds ooff 7979,, 1818 photosphotos (10(10 inin colour),colour), 11 map.map . corundumcorundum bearinbearingg pocketpocketss havhavee beenbeen foundfound iinn AsAs RussiaRussiann gem-bearinggem-bearing areasareas araree graduallygradually variousvarious localities,localities, thethe mainmain oneone beingbeing aatt openeopenedd uupp onconcee more,more, detailsdetails araree givengiven ofof somesome ThalduwThalduwaa iinn AvissawellaAvissawella inin churcchurchh premises.premises. ofof ththee locationlocationss anandd ooff ththee speciesspecies thatthat areare foundfound ExtractionExtraction isis primitiveprimitive.. TherTheree areare twtwoo typestypes ooff atat themthem.. TheTheyy includeinclude beryl,beryl, topaztopaz,, tourmaline,tourmaline, thesethese pocketspockets,, corundumcorundum bearinbearingg pocketpocketss anandd amethystamethyst asas wellwell asas a varietvarietyy ooff mineralsminerals forfor ththee hollowhollow typetype pocketspockets,, ththee formerformer yieldingyielding mainlymainly collectorcollector.. GeologicalGeological detaildetailss araree brieflbrieflyy given.given. patchpatchyy sapphiressapphires (which(which couldcould probablyprobably bbee heatheat M.O'D.M.O'D. treatedtreated anandd turneturnedd intointo blue),blue), somesome yellowyellow andand aa fewfew blubluee sapphires,sapphires, whilwhilee ththee latterlatter onlyonly yieldsyields ·NASSAU,NASSAU, K.,K., 1991.1991. ThThee sevenseven typetypess ooff yellowyellow iroironn pyritepyrite.. ThThee corunducorundumm bearinbearingg pocketpocketss alsoalso sapphiresapphire andand thethe proposeproposedd PonahlPonahloo test.test. yieldyield iroironn pyritpyritee anandd dardarkk orangorangee brownbrown ZeitschriftZeitschriJt der Deutschen GemmologischenGemmologischen tourmalinetourmaline crystals.crystals. E.SE.S.. Gesellschajt,Gesellschaft, 40,40 ,4, 4 ,247- 247-51, 51 ,bibl. bibl . TheThe fadingfading behaviourbehaviour ooff yelloyelloww sapphiresapphire withwith LAFONLAFON,, J-M.J-M.,, COLLYERCOLLYER,, T.A.,T.A., SCHELLER,SCHELLER, T.,T., respecrespectt ttoo lighlightt cacann bebe quitquitee variable,variable, dependingdepending 1991.1991. DatierungDatierung derder Smaragdminerali­Smaragdminerali­ oonn thethe naturenature ooff materiamateriall anandd origioriginn ooff colour.colour. sationensationen dederr GranitGranitee vovonn CampoCampo FormosoFormoso ThThee authoauthorr listslists ththee sevenseven differendifferentt typestypes ooff unundd CarnaibaCarnaiba,, Bahia.Bahia. (Dating(Dating ooff emeraldemerald sapphiressapphires anandd showsshows thathatt ththee mineralizationmineralization ooff thethe granitesgranites ooff campocampo cathodoluminescencathodoluminescentt testtest proposeproposedd bbyy J.J. PonahloPonahlo FormosFormosoo anandd CarnaibaCarnaiba,, BahiaBahia.. FirsFirstt results).results). cancan onlyonly predicpredictt ththee fadinfadingg behavioubehaviourr ooff somesome ZeitschriftZeitschriJt der Deutschen GemmologischenGemmologischen typestypes ooff yelloyelloww sapphire.sapphire. E.SE.S.. Gesellschajt,Gesellschaft, 40,40, 4,4, 241-6,241-6, 2 maps,maps, 1 graphgraph,, 11 table,table, bibl.bibl. NASSAUNASSAU,, K.,K., ROSSMANROSSMAN,, G.R.G.R.,, WOODWOOD,, D.L.,D.L., AnAn ageage ooff 18511851 +/+/-- 4488 MaMa hashas beebeenn obtainedobtained 1992.1992. UnstablUnstablee radiation-induceradiation-inducedd yellow­yellow- foforr five samplessamples ooff phlogopitephlogopitess associateassociatedd withwith greengreen colourcolour iinn grossulagrossularr garnetgarnet.. Gems & ththee emeralemeraldd mineralizationmineralization ooff CampCampoo FormosoFormoso Gemology, 28,28, 3,3, 188-91,188-91, 3 figs. andand CarnaibCarnaibaa granitigraniticc bodiesbodies.. ThiThiss agreeagreess withwith PalePale grossularitegrossularitess from a fewfew AfricanAfrican localitieslocalities thethe radiometricradiometric ageagess obtaineobtainedd from thesethese graniticgranitic werewere irradiateirradiatedd toto a lighlightt toto mediumediumm yellowish­yellowish- rocksrocks.. FurthermoreFurthermore,, ththee ageage ooff ththee phlogopitesphlogopites greengreen,, a coloucolourr whicwhichh fadefadedd rapidlyrapidly iinn daylightdaylight representrepresentss a coolingcooling temperaturtemperaturee ooff aboutabout 400°C400°C andand iinn aboutabout twotwo monthsmonths inin ththee dark.dark. MechanicsMechanics whicwhichh iiss thethe maximummaximum temperaturtemperaturee foforr ththee ofof thethe fadfadee areare explained.explained. ColourColour totooo fugitivfugitivee ttoo crystallizationcrystallization ofof gemgem qualitqualityy emeralds.emeralds. E.SE.S.. havhavee commerciacommerciall significance.significance. R.K.M.R.K.M.

LASNIERLASNIER R.,R., POIROTPOIROT,, J-P.,J-P., VIDAVIDALL P.,P., 1992.1992. NIEDERMAYRNIEDERMAYR,, G.,G., 1992.1992. DasDas EinschlussbilEinschlussbildd vonvon EssaiEssaiss ddee datationdatation eett determinationdétermination ddee SmaragdenSmaragden auauss Serpentinit-Randge­Serpentinit-Randge- l'originel'origine dedess emeraudeseméraudes paparr llaa methodeméthode steinsseriensteinsserien (Smaragde(Smaragde vovomm TypusTypus rubidium-strontiumrubidium-strontium.. Revue de gemmologie,gemmologie, Habachtal).Habachtal). Mineralien Welt, 3,3, 5,5, 46-7,46-7, 4 110,110, 27-9,27-9, 1 fig.fig. photophotoss inin colour.colour. Rubidium-strontiuRubidium-strontiumm datindatingg techniquetechniquess araree HabachtaHabachtall emeralemeraldd containcontainss hornblendhornblendee anandd applieappliedd ttoo thethe identificatioidentificationn anandd characterizationcharacterization biotitebiotite crystalcrystalss asas welwelll asas a varietyvariety ooff colourcolour ooff emeralemeraldd frofromm differendifferentt localitieslocalities andand ooff patternpatternss andand crackscracks.. TheThe relationshirelationshipp betweenbetween syntheticsynthetic emerald.emerald. M.O'D.M.O'D. thethe emeraldemerald andand ititss hosthost rocrockk isis discussed.discussed. M.O'DM.O'D.. LILi YINGPINGYINGPING,, 1992.1992. JadJadee mininminingg atat KhotaKhotann fromfrom ChineseChinese historicalhistorical recordsrecords.. Bulletin ojof thethe PERNYPERNY,, B.B.,, EBERHARDTEBERHARDT,, P.,P., RAMSEYER,RAMSEYER, K.,K., Friends oJJade,of Jade, 7,7 , 29-39.29-39. MULLISMULLIS,, J.J.,, PANKRATHPANKRATH,, R.,R., 1992.1992. JadJadee miningmining atat KhotaKhotann hahass takentaken placplacee overover MicrodistributionMicrodistribution ooff AI,AI, LiLi anandd NNaa inin quartz:quartz: ththee centuriecenturiess andand ChineseChinese recordrecordss havehave beenbeen possiblpossiblee causecausess anandd correlatiocorrelationn witwithh short­short­ useusedd foforr thithiss shortshort study.study. MiningMining goesgoes bacbackk aatt livedlived cathodoluminescencecathodoluminescence.. AmericanAmerican leastleast 3,003,0000 years;years; a lislistt ofof referencereferencess isis given.given. mineralogist, 77,11, 534-44,534-44, 5 photophotoss (3(3 iinn M.O'D.M.O'D. colour)colour),, 8 figs. SecondarySecondary ioionn masmasss spectrometryspectrometry hashas beenbeen LYCKBERG,LYCKBERG, P.P.,, 1992.1992. EineEine reisreisee zzuu dedenn useusedd toto identifidentifyy ththee distributiondistribution ooff AIAI,, LiLi andand NaNa klassischeklassischenn Edelstein-pegmatitenEdelstein-pegmatiten vovonn inin naturalnatural quartzquartz crystalscrystals lookinglooking atat individualindividual MursinkMursinkaa unundd AlabaskaAlabaska sowiesowie zuzu dedenn growtgrowthh layerlayerss whichwhich areare identifieidentifiedd bbyy SmaragdvorkommenSmaragdvorkommen imim BereichBereich vovonn cathodoluminescencecathodoluminescence anandd artificialartificial y irradiation.irradiation. J. Gemm., 1993, 23, 6 371

Changes of trace element concentration by more Canadian Jeweller. than 3 orders of magnitude were observed on a Part 1 - Foiling, dyeing and impregnation. scale of a few tens of micrometres. Zones October 1991. 24. Covers historic enhancement showing intense but short-lived blue techniques, and more recent wax, plastic and oil luminescence contain the highest Al and Li impregnation methods. concentrations with no luminescence shown by Part 2 - Heat treatments can enhance color. regions with low concentrations. The January/February 1992. 24-5. Describes the pronounced variability in the phenomena is standard centuries-old heat treatment processes attributed to conditions of growth (fluctuations and the more recent high-temperature methods of temperature, pressure, pH and composition of employed with geuda corundum and its growth fluids during growth). M.O'D. detection. Part 3 - Not all enhancement techniques are PLATONOV, A.N., SACHANBINSKI, M., equal. March 1992. 24-5, 1 fig. This section WROBLEWSKI, P., IGNATOV, S.I., 1992. includes the less permanent colour enhancement Natural prasiolite from Lower Silesia, Poland. techniques employed with surface-diffused and Zeitschrift der Deutschen Gemmologischen irradiated corundum. Permanent irradiation Gesellschaft, 41, 1, 21-7, 1 photo, 4 graphs, methods including those used for topaz and bibl. diamond are also discussed. Prasiolite is the green, transparent Part 4 - Artificially-coloured diamonds can be noncrystalline variety which can be obtained by detected. April/May 1992. The final part of the heating certain varieties of quartz up to 400- series deals with the irradiation/heat treatment, 600°C. Naturally occurring prasiolites were glass filling and lasering of diamonds, and its discovered in quartz agate géodes in detection. (Author's abstracts) P.G.R. trachybasalts in the sedimentary-volcanic complex of Lower Silesia. The green colour is ROBERT, D., 1992. Reseau cristallin des grenats. distributed unevenly throughout the stone and is Revue de gemmologie, 110, 23-4, 1 fig., 2 caused by Fe seen in the absorption band at photos in colour. 725nm. When heated to 400-500°C the green A synthetic garnet with the trade name colour turns to brown. The authors suggest that Oulongolite is discussed. Specimens have the the colour is primary as a result of specific YAG or GGG composition with various physico-chemical parameters in the quartz dopants. M.O'D. forming solution. E.S. SALERNO, S., 1992. Minéraux et pierres de POIROT, J-P., 1992. Spectrometrie et Madagascar. Revue de gemmologie, 111, 9-10, fluorescence X, des aides pour la 1 photo in colour. détermination de types de gisement de Polychrome sapphires are reported from saphirs. Revue de gemmologie, 110, 7-9, 15 Madagascar. First thought to be alexandrite, the figs. zoned crystals (green and red) had RI 1.770- X-ray spectroscopy and X-ray fluorescence 1.778 and 1.762-1.770 for the ordinary and have been used to determine the origin of extraordinary rays respectively with a sapphires from different localities, which include birefringence of 0.008-0.009, and a specific Burma, Sri Lanka, Kashmir, Vietnam, gravity of 4.0. The mine is in the Betroka area; Madagascar, Thailand, Australia and France. the corundum occurs with cordierite, tourmaline Heated sapphires are also cited. [Translated and biotite. Extraction of the corundum crystals from the English]. M.O'D. without damage is said to be very difficult. M.O'D. PONZONE, A., 1991. Studi termici sulle inclusioni fluide in corindoni di Sri Lanka. La SAPALSKI, C, GOMEZ, F., 1992. Estudio de la gemmologia, 16, 1,7-16, 10 photos in colour. esfalerita de la mina de Aliva, Santander Chemical composition and physico-chemical (Espana). Boletin del Instituto Gemôlogico properties of Sri Lanka corundum are EspanoU 34, 29-39, 27 photos in colour, 2 investigated on the basis of thermal treatment of maps. inclusions. M.O'D. Sphalerite of gem quality in colours ranging from light yellow and green to red is found at the READ, P.G., 1991 - 1992. A four-part series of Aliva Refuge mine, Camaleno, Cantabria, Spain. articles on gemstone enhancement methods. The sphalerite occurs with calcite. 372 J. Gemm., 1993, 23, 6

Gemmological tests are used to identify the treatment. They are found together with black material which very frequently contains colour spinel. 46 rough and 135 faceted stones were zoning, negative crystals and a variety of liquid examined. Mineral inclusions were mainly of inclusions. M.O'D. colourless, tabular prismatic elongated crystals SCHÄFER, W., HENN, U., SCHWARZ, D., 1992. of feldspar surrounded by a halo; partly Smaragde aus de Kesselklamm, recrystallised healing fissures produce triangle Untersulzbachtal, Osterreich: Vorkommen shaped patterns; healing fissures and liquid-filled und Eigenschaften. Aufschluss, 43, 231-40, 3 feathers can show interference colours. Oriented maps, 4 figs, 3 photos in colour. rutile needles have also been observed. E.S. The Untersulzbachtal, celebrated for many years for fine crystals of epidote from SCHLÜSSEL, R., 1992. L'identification au Knappen wand, has produced some emerald. It microscope des diamants aux cavités was found in 1988 in a serpentine-talc lying to artificiellement colmatées à l'aide d'une the south west of an already known beryl- substance vitreuse. Revue de gemmologie, 111, producing area (Leckbachrinne). It is 15-17, 5 photos in colour. accompanied by biotite and muscovite and Methods of identifying glass-filled cavities in actinolite/tremolite crystals appear as inclusions diamonds are discussed. M.O'D. together with them. Constants are given as ne 1.580-1.582, n0 1.588-1.590, DR 0.008, SG SCHMETZER, K., HÄNNI, H.A., JEGGE, E.P., 2.72-2.73. Cr203 content varies from 0.01 to SCHUPP, F-J., 1992. Dyed natural corundum 0.38. M.O'D. as ruby imitation. Gems & Gemology, 28, 2, 112-15, 6 figs. SCHLEE, D., PHEN HOCK CHAN, DORANI, J„ A new imitation ruby was made from pale or FOOK KUNG VOONG, 1992. Riesenbernsteine colourless natural corundum with dye-filled heat in Sarawak, Nord-Borneo. Lapis, 17, 9, 13- and quench cracks. Early examples had 23, 23 photos (19 in colour). colourless areas easily seen by eye; improved Ornamental quality amber has been found specimens need immersion and magnification to with coal deposits in Sarawak, North Borneo, detect colour in cracks, and uncoloured areas. Malaysia. Specimens illustrated show long No fluorescent line at 695nm, but iron bands subparallel flow lines and colours range from were seen in the blue and ultraviolet regions; dye white through colourless, pink, orange, red, fluoresced a strong orange-yellow in LUV but yellowish-green, blue, violet, brown and black. was inert in SUV; acetone swab did not lift it. Between 5-10% of the amber recovered is Corundum probably from Umba in Tanzania. suitable for fashioning. M.O'D. R.K.M.

SCHLÜSSEL, R., 1991. Die Saphir-Lagerstätte SCHWARZ, D., 1991. Geologie und Genese der von Bo Ploi in der Provinz Kanschanaburi, Smaragdvorkommen in der Cordillera Thailand. (The sapphire occurrence at Bo Oriental/Kolumbien. (Geology and genesis of Ploi in the Province of Kanchanaburi, the emerald occurrences in the Eastern Thailand.) Zeitschrift der Deutschen Cordilleras, Colombia). Zeitschrift der Gemmologischen Gesellschaft, 40, 4, 165-80, 2 Deutschen Gemmologischen Gesellschaft, 40, 4, maps, 4 photographs, 10 photomicrographs, 201-31. 2 maps, 2 schematic sketches, bibl. 1 table, bibl. The author gives a detailed description of the The occurrence of sapphires in Bo Ploi has regional and local geological conditions of the been known since 1920; these were worked in eastern Cordilleras in Colombia. Different small scale workings rarely larger than 15-15 genetic models of the emerald mineralisation are sq.m. and varying in depth from 4 to 20 metres discussed. There are still some questions open using similar methods to those used in most for discussion, i.e. the temperature and primitive gem producing countries. In the last composition of the mother solution and the fifteen years, however, the district has been origin of the element Be or of the Be-carrying worked more mechanically and the sapphires are solution (syn- or epigenetic). E.S. found over an area of 100 sq.km. Today this is the most important production of sapphires in SCHWARZ, D., 1992. Die chemischen Thailand. Bo Ploi lies roughly 120km east- Eigenschaften der Smaragde IV. Kolumbien. north east of Bangkok, near the border and near (The chemical properties of emeralds IV. to the River Kwai bridge. The sapphires are dark Colombia). Zeitschrift der Deutschen to middle blue and do not require heat Gemmologischen Gesellschaft, 41, 1, 29-47, 7 J. Gemm., 1993, 23, 6 373

tables, 6 graphs, bibl. Sosso, F., ROMAN E., 1002. Les améthystes The emeralds examined were from Muzo, d'Artigas (Uruguay). Revue de gemmologie, Coscuez, Yacopi, Chivor, Gachala and some 110, 13-14, 3 photos (2 in colour). other not specified occurrences. Ninety emeralds Amethyst from Artigas, Uruguay, is described were subjected to a microprobe. The results of with notes on its occurrence and properties. the chemical analyses are discussed and [Translated from the English]. M.O'D. correlated. The amount in variation and concentration of chromium, vanadium, iron, SUPERCHI, M., 1992. Trésors de l'art italien. magnesium and sodium in these Colombian Analyse gemmologique. Revue de gemmologie, emeralds are summarised. They seem to have 110, 17-19, 4 photos in colour. the lowest iron and magnesium content of all Three jewelled artefacts made in Italy are examined emeralds. E.S. discussed gemmologically. M.O'D.

SHERNAKOW, W.I., LASKOWENKOW, A.F., 1991. TOURET, L., 1992. Les pegmatites de Volhynie Grosse Smaragdkristalle aus den Gruben des (Ukraine). Revue de gemmologie, 110, 25-6. Ural, UdSSR. (Large emerald crystals from Pegmatites of the Volhynie area of the the mines in the Urals, USSR). Zeitschrift der Ukraine produce feldspar, quartz, yellow beryl Deutschen Gemmologischen Gesellschaft, 40, 4, and blue and pink topaz. M.O'D. 189-95, 1 photo, 1 geological map, 1 crystallographic diagram, bibl. WANG TAO, 1992. Recent discoveries and The Ural emeralds usually have a hexagonal, research of ancient jade in PR China. Bulletin prismatic habit - the hexagonal crystals being of the Friends of Jade, 7, 38-41. somewhat distorted. The colour is a rich green A report that suggested that jadeite may have with bluish and yellowish hues, the intensity of been found in Eastern Zhou tombs in Luoyang the colour being dependent on the chromium but a loose usage of the Chinese word yu shows content. A few especially large and beautiful that this is not the case. Poor documentation of emerald crystals are described in details, such as sites hinders work on mineral or artefact the 3369.5 ct. weighing 'Slavnyi Uralaski', eighty occurrences. M.O'D. per cent of which are of gem quality; the 6.55 kg heavy crystal group 'Miner's Glory', the WEIDINGER, W.A., 1992. More on alcohol particularly beautiful 'Nowogodni' and damage to amber (Letter). Gems & 'Swesdar' and a number of other famous Gemology, 28, 2, 140. emeralds. Together with the emeralds Provides three further references to amber alexandrites, phenakites and chrysoberyls are damaged by alcohol, ether and similar solvents found. There are also some rare minerals such as (hair-sprays, perfume, etc.). R.K.M. brommelite, euclase, bertrandite and bowenite. E.S. ZABINSKI, W., 1991. Transvaal 'Jade'. Zeitschrift der Deutschen Gemmologischen Gesellschaft, 40, SHIGLEY, J.E., FRITSCH, E., REINITZ, I., MOON, 4, 233-9, 2 tables, 1 graph, bibl. M., 1992. An update on Sumitomo gem- The name Transvaal jade is given to a green quality synthetic diamonds. Gems & grossular/hydrogrossular with some vesuvianite; Gemology, 28, 2, 116-22, 9 figs. the pink material consists also of Two 5 carat slices of Sumitomo synthetic grossular/hydrogrossular with different lattice diamond, from cube and octahedral crystals parameters. The green is caused by the presence respectively, revealed colour zoning, graining, of Cr, the pink by Mn. E.S. strain and luminescence reflecting their initial crystal habits. Crystal morphology is thought to ZWAAN, P-C, 1992. La kornerupine affect the properties. Material is used for d'Embilipitiya, Sri Lanka. Revue de industrial heat-sinks, etc., and is not intended gemmologie, 110, 5-6, 2 photos in colour, 1 for jewellery use. Both samples were inert to map. LUV but gave weak orange-yellow under SUV, a Kornerupine is found at Embilipitiya in the reaction which may be seen in type lb natural south of Sri Lanka. SG=3.284, RI= 1.660, 1.672. diamonds. Cathodoluminescence emphasizes Black and red rutile crystals are found as growth patterns. The cube sample was type lb. inclusions in cut stones. [Translated from the The octahedral sample was found to be a English.] M.O'D. mixture of types Ib+IIa+IIb diamond, so far not seen in natural diamond. R.K.M. 374 J. Gemm., 1993, 23, 6

Book Reviews

BALFOUR, I., 1992. Famous diamonds. Second properties, colour and luminescence. Next edn. NAG Press, Colchester, pp. 245, illus. comes a description of topaz crystal morphology in black-and-white and in colour. £29.00. and of inclusions. Topaz geology and a summary The first edition of this book was well of world sources complete the book. received and as so often happens sparked off the Early on the author discovered that the discovery of several more outstanding stones! substitution of the hydroxyl ion for fluorine in Considerable attention is given to the superb the topaz structure affects the crystallography Centenary diamond, weighing in its cut form and properties in hitherto unrealized ways and 273.85ct and the largest diamond to be cut by this theme is followed throughout this book the application of the most modern techniques. which all gemmologists should possess. The colour picture of the faceted stone shows, as M.O'D. few diamond photographs do, some of the dispersion of this beautiful stone. It was found JOYCE, K., ADDISON, S., 1992. Pearls, ornament in 1986 at the Premier mine and weighed 599ct and obsession. Thames and Hudson, London. in the rough. pp. 253, illus. in black-and-white and in Other stones, such as the pink Kirti-noor colour. £38.00. have only recently come to public attention (it is An uninformative introduction by Sumiko a Golconda stone and has been in a private Mikimoto precedes a very attractive, illustrated collection in India until recently). Some, such book with a fairly general text. The survey covers as the 'Unnamed Brown' have no name (this the use of pearls in a variety of contexts with stone is now a modern fire-rose cushion shape of emphasis on costume; this is well illustrated by a 545.67ct from a rough crystal weighing number of reproductions of portraits in which 755.5Oct; the cut stone is a very high 72.2 per pearls are prominent. The historical material has cent of the original weight). to be selective but is well put together and As in the previous edition the text surrounds interesting to read. There is a reasonably useful black-and-white and coloured photographs and bibliography and a much less useful glossary. the price is most reasonable for so interesting a Read the book for the pictures at least; the book. M.O'D. flowery style disguises quite a lot of valuable information and has to be waded through. HOOVER, D.B., 1992. Topaz. [Butterworths M.O'D. Gem Books.] Butterworth-Heinemann, Oxford, pp. xiv, 207, illus. in black-and-white KOCKELBERGH, I., VLEESCHDRAGER, E., and in colour. £35.00. WALGRAVE, J., 1992. The brilliant story of Some topaz may be triclinic and some Antwerp diamonds. MIM n.v., Antwerp, pp. physical and optical values may be more 303, illus. in black-and-white and in colour. dependent on locality and formation than upon BF2,895. colour. This study of topaz is particularly A book illustrating the history of Antwerp in readable with a lucid style and very extensive celebration of its position as Cultural Capital of references. Many new concepts similar to those Europe 1993 and forming part of the 'Ortelius' opening this review are presented with series gives a great deal of information on the sustainable evidence. history of the city. The text is easy to read, with The book opens with a study of the derivation several pictures on each page: they include of the word 'topaz5 and of the occurrence of the reproductions of significant documents and of mineral in historical accounts. Large and portraits with many illustrations of famous notable topaz gemstones and crystals are diamonds. The diamond trade has done much described before an account of topaz chemistry, to maintain Antwerp's favourable trading crystal structure, optical properties, physical position and although work on small goods has J. Gemm., 1993, 23, 6 375

largely moved to India the presence in the city of white. Approximately £60.00. the Diamond High Council will help to ensure From a gemmological point of view the continuance of Antwerp's domination of the lamprophyres sprang into prominence with the European diamond handling and polishing discovery that the supposed kimberlite pipe, trade. M.O'D. which provides many gem and industrial quality diamonds at Kimberley, Western Australia, is a MARSHALL, DJ., 1988. Cathodoluminescence of lamprophyre now known as the Argyle pipe. geological materials. Unwin Hyman, Boston. The first section of the book offers a history pp. xiv, 146, illus. in black-and-white and in of the term lamprophyre; the suffix -phyre is colour. £65.00. correctly used in this context to denote a Over the past few years cathodoluminescence porphyritic character. The term was first used in has been advocated as a useful gemmological 1874 for a rock characterized by glistening test. Here the whole range of geological phenocrysts first described from the German materials, including gemstones, has been Fichtelgebirge. Recent studies have begun to subjected to energetic electrons and the most suggest that lamprophyres form a vital insight significant results are detailed in a way which is into the deep mantle and mantle processes and easy to understand. History and instrumentation thus into the formation of materials such as of the method are outlined first with definitions diamond and gold. The term lamproite was and a survey of the results obtained from some coined in 1923 to describe extrusive rocks of common minerals arranged by classes. The lamprophyric aspect. Lively discussion of the cathodoluminescence of the feldspar and quartz nature of lamprophyres continues and several group is extensively described, each group classifications have been postulated; in one having a chapter of its own; the carbonates are hierarchical scheme kimberlites are placed with similarly treated. The cathodoluminescence of four other rock types in the first order, within gemstones has a page of its own; there is an which many other smaller categories are appendix outlining the photographic methods distinguished. From the mineralogical aspect used in the various tests. An excellent the assemblage of minerals is probably that part bibliography completes the book. of the lamprophyre topic of greatest interest; Even though the treatment of gemstone lamprophyres carry essential amphibole and/or cathodoluminescence is small, the general text biotite-phlogopite and also abnormal amounts of contains much to interest the gemmologist. Not minerals rich in F, Cl, S03, C02 and H20. least in importance is the description of the ways Mg-rich mafic minerals such as diopside and in which different types of luminescence are forsterite are found with Na-K feldspars and caused and the review of a large number of some quartz. Tremolite actinolite phases, for individual species under test. M.O'D. example, found in some igneous rocks, are not found in lamprophyres. Chapter 9, dealing with NABARRO, F.R.N. (ed.), 1992. Dislocations and economic geology, will be found particulary disinclinations. Dislocations in solids. North- interesting to gemmologists as it includes a table Holland, Amsterdam. Vol. 9, pp. x, 424, of diamondiferous lamprophyres excluding illus. in black-and-white. US$208.50. kimberlites. At the time of writing, some With chapter numeration continuing from the kimberlites at least, had been reclassified as first eight of the series, this volume deals with a lamproites and the premise made that summary of the advances in the electron lamprophyric rocks are the only confirmed microscopy of dislocations, the study of internal magmatic sources of diamond. friction derived from kinks in dislocations lying There are other chapters of interest but the in Peierls valleys, dislocation dynamics in face- main feature is a very extensive bibliography. centred cubic and body-centred cubic metals. There is also a table of confirmed occurrences of An overview of rotational deformation is given different types of lamprophyres. This type of with an exhaustive bibliography. Many of the work, which will inevitably attract considerable topics discussed will be of great interest to discussion and amendment, is the type of study crystal growers. M.O'D. upon which our gemmological investigations ultimately depend, particularly at the ROCK, N.M.S., 1991. Lamprophyres. Blackie, prospecting and recovery end. M.O'D. Glasgow, pp. viii, 285, illus. in black-and- 376 J. Gemm., 1993, 23, 6

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

GIFTS TO THE GAGTL 'Mines and mineral deposits of South Africa'. The Association is most grateful for gifts of On 17 February 1993 at Church House the gems and gem materials for research and teaching video 'Gemstones of America' was shown. purposes from the following: On 17 March 1993 at Church House, Richard Miss Mary J. St Amand, FGA, of Sausalito, Digby gave an illustrated talk on 'Cameos and California, for moonstone from Mexico. intaglios'. Mary Burland for synthetic rubies. GEMSTONE INCLUSIONS MEMBERS' MEETINGS A set of 30 display pictures of gemstone inclu­ London sions is available for sale. Recently they formed a The following meetings, that have been held in travelling exhibition and consist of 40 x 29 cm the GAGTL's new Gem Tutorial Centre on the prints mounted in glass/hardwood frames (67 x 54 second floor at 27 Greville Street, London EC IN cm) with explanatory captions. 8SU, have proved very successful and have For full details contact CR. Burch, FGA, at 4 attracted a 'full house' on every occasion. West Moor Drive, Cleadon, Nr Sunderland, Tyne On 25 January 1993 Michael O'Donoghue gave and Wear SR6 7TW. Telephone 091-536 2386. a talk on 'Gems of Pakistan'. A number of the gems mentioned were on display for the evening. MEETINGS OF THE COUNCIL OF On 8 February 1993 Ana I. Castro and Stephen MANAGEMENT Kennedy gave an illustrated talk on 'Emeralds in At a meeting of the Council of Management the Laboratory'. held on 13 January 1993 at 27 Greville Street, On 24 February Peter Read gave a talk entitled London EC IN 8SU, the business transacted 'New gem testing instruments'. included the election of the following: On 8 March 1993 Dr Alan Collins gave an illus­ trated talk on the 'Colour in diamonds', bringing Fellowship those present up-to-date with current research on Bakker, Frederik CS., Zwaagdijkwest, The the subject. Netherlands. 1992 On 31 March 1993 David Callaghan gave a talk Leung, Florence Lai Ping, Hong Kong. 1992 entitled 'From gem to jewel'. Spanbok, Gary, Edgware. 1992 Winkelmolen, Karin, Beesel, The Netherlands. Midlands Branch 1992 On 27 January 1993 at Dr Johnson House, Bull Zaveri, Pragnesh, Bombay, India. 1992 Street, Birmingham, Edgar Taylor gave a talk entitled 'Fossicking in Wales'. Ordinary Membership On 26 February 1993 at Dr Johnson House, Cho, Eun-Kyung, Seoul, Korea. Robert Campbell-Legg spoke to members on Crane, Simone, London. 'The art of the engraver'. Kalischer, Janice, London. On 26 March 1993 at Dr Johnson House, Mcintosh, Robert P., Penicuik. Peggy Stock gave a talk entitled 'Crystal healing'. Ruhmer, Fiona, Brackenbury Village, London. Woodbridge, Roger, Upminster. North West Branch On 20 January 1993 at Church House, Hanover At a meeting of the Council of Management Street, Liverpool 1, David Pelham gave a talk on held on 17 February 1993 at 27 Greville Street, JJ.. Gemm.Gemm.,, 1993,1993, 2323,, 6 373777

GAGTL GEM TUTORIAL CENTRE 27 GreviUe Street, London EC1N 8SU Diamond Grading Weekend Course Diploma Workshop j 8-9 May 1993 1-2,5-6, 8-9 and 19-20 June 1993 For retailers* valuers and those involved in Two days of intensive practical tuition for trading diamonds* who need an insight into students approaching examinations, with a gem diamond grading, simulants and mock exam; aîso suitable for those who need treatments* intensive gem therapy. Price £210.00+VAT Price £125.00 + VAT far mö days GAGTL students£85.00+ VAT Enquire within - Ornamental rocks Identifying hardstone carvings 15 July 1993 11 May 1993 A day looking at all aspects of ornamental rocks. Price £90.00+ VAT Includes a short walk around the Hatton Garden area discovering materials used in buildings. A day of pearls Price £90.00+VAT 12 May 1993 Price£9QM+VAT Enquire within - Organic gem materials 22 July 1993 A day looking at all aspects of organic gems> Preliminary questions and answers natural, treated and imitation. 14 May 1993 Price £90.00+VAT The chance for Preliminary examination candidates to find out from tutors and Two days of diamonds examiners what is required of them in the 15-16 September 1993 examination. For an insight into the gem diamond origins, Price£15.00 including VAT grading, simulants and treatment. Price £190.00+VAT

Preliminary Workshop A day of beads and stringing 12-14 October 1993 20 May and 8 July 1993 One-day practical tuition for Preliminary For anyone who wishes to investigate the great students and anyone who needs a start with variety of beads, natural or artificial, and the instruments, stones and crystals. intricate methods for stringing beads or pearls. Price £38.00+ VAT Price £90.00 + VAT (inclusive of materials) GAGTL students£27.00+VAT For further information contact the GAGTL Education Department on 071 -404 3334.

LondonLondon ECINEC IN 8SU,8SU, thethe businesbusinesss transactedtransacted BeesleyBeesley,, c.R.,C.R., NeNeww York,York, NY.NY.,, USA.USA. includedincluded ththee electioelectionn ofof ththee following:following: BellBell,, Martin,Martin, Albuquerque,Albuquerque, N.Mex.N.Mex.,, USA.USA. BendinghamBendingham,, Michiko,Michiko, TokyoTokyo,, Japan.Japan. FellowshiFellowshipp BoehmBoehm,, Edward,Edward, CarlsbadCarlsbad,, Calif.,Calif, USA.USA. BruciakBruciak,, ThomaThomass M.,M., VeniceVenice,, Fla.,Fla., USA.USA. 19861986 BrunsBruns,, FrederiFrederikk H.,H., TucsonTucson,, Ariz.Ariz.,, USA.USA. DDee RuiterRuiter,, JacobJacobaa E.,E., WaddinxveenWaddinxveen,, TheThe Crevoshay,Crevoshay, George,George, UptonUpton,, Mass.,Mass., USA.USA. NetherlandsNetherlands.. 19921992 GaskellGaskell,, BenjaminBenjamin H.,H., London.London. Kim,Kim, JonJongg Pil,Pil, Seoul,Seoul, Korea.Korea. 19921992 GuestGuest,, VanessVanessaa A.A.,, ArnoldArnold,, Nottingham.Nottingham. Lu,Lu, MiltonMilton R.K.,R.K., TaipeiTaipei,, Taiwan.Taiwan. 19831983 Harada,Harada, Kayoko,Kayoko, KanagawKanagawaa Pref,Pref, Japan.Japan. Sohn,Sohn, JeongJeong Sun,Sun, Seoul,Seoul, Korea.Korea. 19921992 IkutaIkuta,, Miwa,Miwa, KyotoKyoto,, Japan.Japan. Tenhagen,Tenhagen, JosepJosephh W.W.,, MiamiMiami,, Fla.,Fla., USA.USA. 19691969 InoueInoue,, Keiko,Keiko, Osaka,Osaka, Japan.Japan. Wong,Wong, MiMinn WanWan,, KowloonKowloon,, HongHong Kong.Kong. 19921992 Ishida,Ishida, Masako,Masako, OsakaOsaka,, Japan.Japan. Kanamori,Kanamori, TomohiroTomohiro,, Osaka,Osaka, Japan.Japan. OrdinarOrdinaryy MembershipMembership KanedaKaneda,, Kenichiro,Kenichiro, HyogoHyogo PrefPref,, Japan.Japan. AikawaAikawa,, Atsuko,Atsuko, Heusenstamm,Heusenstamm, Germany.Germany. Kashi,Kashi, KenyaKenya,, Osaka,Osaka, Japan.Japan. 378 J. Gemm., 1993, 23, 6

FORTHCOMING MEETINGS London Throughout 1993 there is a programme of meetings on the second floor at 27 Greville Street. Refreshments will be available from 6.00 p.m. and lectures will start at 6.30 p.m.; these will be followed by discussion and closing about 7.45 p.m. The charge for a member will be £3.50 and, as places are limited to 55, entry will be by ticket only, obtainable from GAGTL.

11 May 'Engraved Gems' Christopher Cavey 14 June Reunion of Members, AGM and 'Bring and Buy' 20 September 'Photographing minerals and gems' Frank Greenaway 6 October* 'Diamonds in the Laboratory' Eric C. Emms 8 November 'Thai evening' Amanda Good and Martin Issacharoff 22 November 'CIBJO matters' - the gem trade in Europe Harry Levy 7 December* 'Pearls in the Laboratory' Ana I. Castro and Stephen Kennedy

* PLEASE NOTE: 'Diamonds in the Laboratory' is one week later and Tearls in the Laboratory' is one day earlier than previously scheduled.

Midlands Branch

30 April Annual General Meeting followed by a gem collection talk

The meeting will be held at Dr Johnson House, Bull Street, Birmingham. Further details from Gwyn Green on 021-445 5359.

North West Branch

19 May 'Lalique jewels, from the 1992 Paris Exhibition' Dr J. Franks 16 June Members and friends evening. Bring and buy: crystals, books and instruments, and exchange of views 15 September Jonathan Condrup from Sotheby's 20 October 'Minerals in the Bronze Age'. The Great Orme Mine. Tony Hammond 17 November Annual General Meeting

Meetings will be held at Church House, Hanover Street, Liverpool 1. Further details from Joe Azzopardi on 0270-628251.

Kimura, Michihoko, Hiroshima Pref, Japan. Okuda, Etsuko, Osaka, Japan. Kitawaki, Hiroshi, Saitama Pref, Japan. Otomo, Ryoko, Miyagi Pref, Japan. Kitawaki, Junko, Osaka, Japan. Oyama, Yumiko, Shiga Pref, Japan. Kobayashi, Masahide, Osaka, Japan. Purkiss, Christopher R., London. Kodama, Aki, Osaka, Japan. Reay, Kenneth, Worplesdon. Kokubu, Ozusa, Tokyo, Japan. Reynolds, Stephen, Cleeve Hill, Cheltenham. Lahogue, Pascale, Tervuren, Belgium. Richardson, Andrée J., Alverstoke. Lee, Kyung Hae, Fukuoka Pref, Japan. Senoo, Kiyoko, Saitama Pref, Japan. Nakamura, Maya, Hyogo Pref, Japan. Shibata, Hitoshi, Osaka, Japan. Nihira, Hiroko, Tokyo, Japan. Shikano, Chisa, Chiba Pref, Japan. Ninomiya, Tsuyosho, Fukuoka Pref, Japan. Sibutani, Yuko, Osaka, Japan. Nishizawa, Takako, Osaka, Japan. Stilwell, Lesley E., Tring. Ogihara, Shigenori, Saitama Pref, Japan. Tada, Reiko, Osaka, Japan. Ohki, Kuniyuki, Osaka, Japan. Tamura, Osamu, Osaka, Japan. Okada, Takayuki, Osaka, Japan. Thorne, Bridget, London. J. Gemm., 1993, 23, 6 379

Ushioda, Motofusa, Tokyo, Japan. Prior, Louise, London. 1993 Valentine, Peter, Maidstone. Scott, Kenneth M., Cleghorn. 1993 Vuillet a Ciles, Pierre, Epsom. Diamond Membership Withers, Justine M., Redhill. Lupton, Elaine, Paddock Wood. 1992 Yamashita, Masayo, Tokyo, Japan. Yanagisawa, Kumiko, Gunma Pref, Japan. Fellowship Yasuda, Kiyotaka, Osaka, Japan. Koetsier, Anya, Maida Vale, London. 1992 Yokote, Hideki, Fukuoka Pref, Japan. Van Keulen, Simone J.C., Amsterdam, The Yoshikawa, Shoichiro, Kanagawa Pref, Japan. Netherlands. 1992

Gold Laboratory Membership Ordinary Membership Graff Diamonds Ltd., 16 Greville Street, Hatton Asch, Theodore, Davis, Calif, USA. Garden, London EC1N 8SQ. Bollack, josee, Strasbourg, France. Gruet, 52 Rue La Fayette, 75009-Paris, France. Carson, Michael J., Boston. King's Diamond Trading Company, Rm 701-5 Jones, Donald, London. Lane Crawford House, 70 Queen's Road, Karmali, Amin, Wembley. Central, Hong Kong. Levinson, Alfred A., Calgary, Alberta, Canada. Pattni, Hirnat H., Chilwell, Nottingham. At a meeting of the Council of Management Proudlove, David, Ardfern, Argyll. held on 17 March 1993 at 27 Greville Street, Raphael, Daniel P., London. London EC1N 8SU, the business transacted Wu, Chao-Ming, Golders Green, London. included the election of the following: Gold Laboratory Membership Transfer to Fellowship and Diamond J. & B. Cousins & Sons Ltd, 8,9,9a Sun Street, Membership Canterbury, Kent. Bakagianni-Sabou, Aristea, Nikea-Piraeus, Greece. 1993 Ordinary Laboratory Membership Gofa, Sophia, Athens, Greece. 1993 Gold Arts, 7 Brighton Place, Brighton BN1 Hare, Rebecca, Fleet. 1993 1HD.

\ Pearls Coral Amber Bead Necklaces Carvings Cameos M ineralSpecimens7 r-, ./ ..,z The World I II II I of Gemstones

j ~y=:=::o ~ .;; f ~ ·:l ~ Ruppenthal (U.K.) Limited ·~ " :0;- '"~ ""x .;; Gemstone of every kind, cultured pearls, coral,amber, ivory, bead necklaces, § ~ hardstone carvings, objets d'art, gold gemset jewellery, antique jewellery, ~ ~ 1:. mineral specimens, mineral and gemstone study collections. ~ . ~ ::.: Weoffer a first-class lapidary service. ~ '~ v; ..to We are also interested in purchasing any unusual gemstones, gemstone t>: . necklaces, objets d'art, figurines, cameos, intaglios, antique jewellery from any ~ 0: <:: cs period, antiquarian books of the gemstone industry etc. " c," ~ '" ~ ~ 6 Warstone Mews London Showroom, r­ -e Warstone Lane 3rd Floor, 20-24 Kirby Street, ·~. ~ Birmingham B 18 6J B Hatton Garden, London ECIN 8TS r- .., ~ cc Tel:021-236 4306 Tel:071-405 806816563 §. 8 Fax:021-2121905 Fax: 071-831 5724 V.I AntiqueJewellery Modern 18etand 9etGem-set Jewellery ~"-.. 380 J. Gemm., 1993,23,6

Because whether you live in England or Thailand, gemstones and minerals are just as fascinating. And no oth r magazine covers the gem and jewelry arts like Lapidary Journal. Every month, you'll hear from the field's top experts as they report to you the latest discoveries in mineralogy and gemology. Lapidary Journal takes you on gemstone expeditions, invites you into studios of noted artisans, and then sets up shop in your own home to teach you the most basic to the most revolutionary cutting and jewelry making techniques. What's more, only LapidaTy Journal intro- duces you to over 450 suppliers and services that you can buy and order through the mail. If you collect, cut, or design jewelry with gems and minerals, you won't want to miss another issue. Subscribe today by sending us your name and address with payment to: Lapidary Journal , P.O. Box 124-JG, Devon, PA 19333. Your subscription is payable in U.S. dollars only.

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>.'. C c,li!:"'(.1te d S i- e R.R. HOLTHOLT && CO.CO. LTD.LTD. n/iJ ~. 0 9988 HattoHattonn Garden,Garden, LondoLondonn EelEC I NN 8N8NXX *m~* HiHipp SanSangg TradinTradingg CCoo TelephonTelephonee 071-405071-405 0197152860197/5286 ChampagnChampagne eArcade A rcad,e. Kimberlc Kimberlyey RoadRoad., Kowloon Kowloon., Hon Iiongg KonKongg TeleTelexx 2187218799 MinholMinholtt TelTe: l:(852 (852) )36 3677 974 97477 Faxra:x :(852 (B52)) 73 7399 76576544 MailinM ailingg Address Add ress:: K.P.O K.P.O. .Bo !:loxx 96532 96';32., T.S.T T.S.T. .Hon Hongg KonKongg Notes for Contributors The Editors are glad to consider original is consistent with clear indication of the articles shedding new light on subjects of content of the paper. It should be followed by gemmological interest for publication in the the names (with initials) of the authors and by Journal. Articles are not normally accepted their addresses. A short abstract of 50-100 which have already been published elsewhere words should be provided. Papers may be of in English, and an article is accepted only on any length, but long papers of more than the understanding that (1) full information as 10 000 words (unless capable of division into to any previous publication (whether in parts or of exceptional importance) are English or another language) has been given, unlikely to be acceptable, whereas a short (2) it is not under consideration for publication paper of 400-500 words may achieve early elsewhere and (3) it will not be published publication. elsewhere without the consent of the Editors. Twenty five copies of individual papers are Papers should be submitted in duplicate on provided on request free of charge; additional A4 paper. They should be typed with double copies may be supplied, but they must be line spacing with ample margins of at least ordered at first proof stage or earlier. 25mm all round. The title should be as brief as

ADVERTISING IN Rates per insertion, excluding THE JOURNAL OF VAT, are as follows: GEMMOLOGY Whole page £180 Half page £100 The Editors of the Journal invite Quarter page £60 advertisements from gemstone and mineral dealers, scientific Enquiries to Mrs M. Burland, instrument makers, publishers Advertising Manager, and others with interests in the Gemmological Association, gemmological, mineralogical, 27 Greville Street, lapidary and jewellery fields. London EC1N8SU. Volume 23 No. 6. April 1993

1 '"«Journal of Gemmology Contents

A method for obtaining optic figures from inclusions J.I. Koivula 323 Freshwater pearl cultivation in Vietnam G. Bosshart, H. Ho, E.A. Jobbins and K. Scarratt 326 The location, geology, mineralogy and gem deposits of alexandrite, cat's-eye and chrysoberyl in Brazil J. Cassedanne and M. Roditi 333 Jaspers from Swierki near Nowa Ruda, Lower Silesia, Poland W. Heflik, Ai. Pawlikowski, T. Sobczak and N. Sobczak 356 Test report on the Hanneman Mini-cube II P.G. Read 360 Notes from Tucson '93 E.G. Emms 362 Gemmological Abstracts 364 Book Reviews 374 Proceedings of The Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 376

Copyright© 1993 The Gemmological Association and Gem Testing Laboratory of Great Britain Registered Office: Palladium House, 1-4 Argyll Street, London W1V IAD

ISSN: 0022-1252

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