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Volume 24 / No. 5 / 1995 Volume 24 No. 5. January 1995 rhe Journal of Gemmology The Gemmological Association and Gem Testing Laboratory of Great Britain President E.M. Bruton Vice-Presidents A.E. Farn, D.G. Kent, RK. Mitchell Honorary Fellows R.T. Liddicoat Jn1'., E. Miles, K. Nassau, E.!\. Thomson Honorary Life Members D.J. Callaghan, E.A. Jobbins Council of Management CR Cavey, T.J. Davidson, N.W. Decks, E.C Emrns, RR Harding, 1. Thomson, V.I'. Watson Members' Council A.J. Allnutt, P.J.E. Daly, P. Dwyer-Hickey, R Fuller, B. Jackson, J. Kessler, C. Monnickendam, L. Music, J.B. Nelson, K. Penton, P.G. Read, 1. Roberts, R Shepherd, R Velden, CH. Winter Branch Chairmen Midlands: J.W. Porter North West: 1. Knight Examiners A.J. Allnutt, MSc., Ph.D., rCA L. Bartlett, BSc., M.Phil., FCA, DCA E.M. Bruton, FCA, DCA CR Cavey, FCA S. Coelho, BSc., rCA, DCA AT Collins, BSc., Ph.D. B. Jackson, FCA, E.A. [obbins, BSc., CEng., fIMM, FCA C.B. Jones, BSc., Ph.D., FCA D.C. Kent, FCA R.D. Ross, BSc., FCA P. Sadler, SSc., PGS, PCA, DCA E. Stern, rCA, DCA Prof. 1. Sunagawa, DSc. M. Tilley, GC, FCA C Woodward. BSc., FCA, DCA The Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London ECIN 8SU Telephone: 071-404 3334 Fax: 071-404 8843 ^Journal of Gemmology VOLUME 24 NUMBER 5 JANUARY 1995 Editor Dr R.R. Harding Production Editor M.A. Burland - Assistant Editors M.J. O'Donoghue P.G. Read Associate Editors S.M. Anderson London Dr C.E.S. Arps Leiden G. Bosshart Zurich Dr A.T. Collins London Dr J.W.Harris Glasgow Prof. R.A. Howie Derbyshire DrJJMLOgden Cambridge Dr J.E. Shigley Santa Monica Prof. D.C. Smith Paris E. Stern London Prof. I. Sunagawa Tokyo Dr M. Superchi Milan CM. Woodward London Any opinions expressed in The Journal of Gemmology are understood to be the views of the contributors and not necessarily of the publishers. Cover Picture Photomicrograph of maw-sit-sit (MSS1) in plane polarized light. Kosmochlor (bluish-green and yellow, due to different orientation), amphibole (white) and chromite/magnesiochromite (black, opaque). (See Studies on kosmochlor, jadeite and associated minerals in jade of Myanmar, p.315) ISSN: 1355-4565 314 J. Gemm., 1995,24,5 In this issue... The Far East again figures strongly in the The third paper deals with the history of papers published in this issue and there is pearl production in the Gulf of Mannar new information on gems from Myanmar, and Sri Lanka. A fascinating insight is Vietnam, Sri Lanka and Siberia. given into how pearls were traded and The first paper deals with the relation­ who controlled the trade from the earliest ship of jadeite with kosmochlor - the times. An account of the fluctuations in intense green mineral now found in maw- production culminating in its cessation in sit-sit but first identified in extra-terrestrial the 1950s implicates misguided, if well- rocks. The composition of maw-sit-sit is meaning, government interference. discussed and the authors present the case Over the past thirty years Siberia has for calling it jade. been best known in the gem world as the The recent development of deposits of source of Russian diamonds. But over the ruby at Mong Hsu, again in Myanmar, has centuries it has provided a wide range of been extremely rapid - amazingly so when gem and decorative materials, many of one contrasts it with the several centuries which were utilized in the Faberge work­ of painstaking output from Mogok. shops and became well known. Not so well However, this is a result not only of market known, perhaps, are the reserves of hunger for the fine stones from this local­ Siberian jet, which was also a popular ity, but also of the improvement in material for carving. The paper by communications, the removal of 'procedu­ S. Glushnev fills a gap in the general ral' obstacles and the availability of new appreciation of the history and develop­ technologies. With such technologies it is ment of Siberian jet and comes at a time possible at one end to quickly extract gem when interest in the potential of Siberian gravel by the ton and at the other to use a materials is reawakening. higher percentage of the product by heat- Finally two papers on peridot and syn­ treating stones to improve their colour. thetic diamond provide topical Many rubies from Mong Hsu are heat- information on stones that may well treated and the methods of distinguishing become more significant in the trade. them from untreated stones, using - yes - new technology, are outlined by C.P. Smith. R.R.H. © Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 J. Gemm., 1995, 24,5 315 Studies on kosmochlor, jadeite and associated minerals in jade of Myanmar Win Htein* and Aye Myo Naing** *Universities' Research Centre (URC), University of Yangon, Yangon, Myanmar ** Myanma Gems Enterprise (MGE), Yangon, Myanmar characters of jadeite, pure or impure. Abstract By petrographic and X-ray diffraction Physical, optical and X-ray data are studies, some amphiboles and pyroxenes given for jadeite, kosmochlor and other including kosmochlor (previously known associated minerals in various jades of as ureyite, Fleischer, 1965) were found Myanmar. Jadeite jade is a monomineralic (Figures 1 and 2) in association with jadeite or polymineralic crystalline in some jade specimens (Naing, 1990). The aggregate. In the polymineralic variety, present work has also confirmed the occur­ jadeite occurs in intimate associations rence of kosmochlor as a terrestrial mineral with edenite, richterite, tremolite, kosmochlor (Ou Yang; 1984, Harlow and Olds, 1987) and enstatite. Maw-sit-sit is and supported the probable existence of essentially composed of kosmochlor and jadeite-kosmochlor solid solution (Mevel chromite/magnesiochromite with or and Kienast, 1986). However, the amphi­ without amphiboles and enstatite, but boles associated with jadeite and described devoid of pure jadeite. in the present work are different from The occurrence of kosmochlor is confirmed those described by Mevel and Kienast. as a terrestrial mineral. In addition, neither albite nor quartz has Jadeite-kosmochlor solid solution yet been found in any of the true jade spec­ suggests that the term 'jade' could be imens studied, but some jade-like rocks do extended to include kosmochlor as a occur in the jade mine areas, for instance jade mineral in the gemmological sense. the locally called 'pa-lwan' resembles jade but contains albite, quartz and minor epidote. 'Maw-sit-sit' from Tawmaw is Introduction regarded as a kind of jade-like material Jade of Myanmar (Burma) has a world­ (not real jade) by most jade dealers and by wide reputation for its fine quality. There Myanma Gems Enterprise, but the speci­ are various jade types differing in colour, mens shown in Figures 3,4 and cover transparency and mineral association, and picture do not contain pure jadeite. many quality grades including Imperial, commercial and utility, are produced from Nomenclature of jade Myanmar. They are subdivided into sub- Gemmologically the term 'jade' is grades in the jade trade. These qualities applied to only two mineral species - and varieties of jade may be directly jadeite and nephrite. For some jades of related to the mineralogical and chemical Myanmar, the term jade will refer not only © Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 316 J. Gemm., 1995,24,5 Fig. 1. Sp. No. J4 consisting of jadeite, richterite/ Fig. 2. Sp. No. J13 consisting of jadeite, richterite/ edenite, tremolite and kosmochlor. edenite, kosmochlor and tremolite. Fig. 3. Sp. No. MSS 2. Maw-sit-sit consisting of kos­ Fig, Sp. No. MSS 3. Maw-sit-sit consisting of kos­ mochlor, tremolite, edenite/richterite and mochlor, enstatite, chromite and chromite. magnesiochromite. J. Gemm., 1995, 24, 5 317 to jades composed only of jadeite but also variable saturations to nearly black. to jadeite plus other associated mineral or Qualitative point analysis on vividly minerals. When a jade specimen is essen­ coloured specimens by JEOL JXA 840A tially monomineralic, the term 'jadeite jade' electron probe micro-analyzer provided or 'pure jade' will be used. If the specimen the following information on the chemical is polymineralic the term 'impure jade' will constituents which may be causing the be applied in the present work. colour: Mevel and Kienast have demonstrated by electron probe microanalysis that a Emerald-green to light green: wide range of solid solution exists between Cr(colour saturation depends upon pure jadeite and nearly pure kosmochlor Cr concentration). Kosmochlor itself (i.e. kosmochlor 85 jadeite 15). is deep emerald-green especially in maw-sit-sit Physical characteristics of jade Texture Greyish-green and greenish-grey: Well formed, individual crystals of Fe, Mg, + Cr jadeite have not yet been found in Myanmar. All the jade samples are Yellowish, brownish and reddish: compact, massive and generally granular Fe (Ti, V, Cr and aggregates. The states of aggregation may Mn were not detected in jades of be different from one specimen to another. these colours) Commonly, fine- and coarse-grained aggregates are associated in a single jade Mauve and pinkish: specimen. Lath-shaped, elongated or Manganese fibrous aggregates of prismatic crystals can be seen in hand specimens. The con­ Dark green and greenish black: stituent crystals may be subparallel or Mg, Ca, Fe (constituent elements of randomly oriented and their textures are amphiboles which may be responsi­ commonly best displayed on weathered ble for these colours) crusts. X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses showed that Hardness the mineral and chemical compositions of The relative hardness varies in practice crusts were not significantly different from from slightly greater than 6 (coarse-grained those of fresher parts of the rock.
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