Amber with Mite Inclusion
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F^ the Journal of \ Y Volume 26 No
Gemmologf^ The Journal of \ y Volume 26 No. 6 April 1999 II J The Gemmological Association and Gem Testing Laboratory of Great Britain Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London EC1N 8TN Tel: 0171 404 3334 Fax: 0171 404 8843 e-mail: [email protected] Website: www.gagtl.ac.uk/gagtl President: Professor R.A. Howie Vice-Presidents: E.M. Bruton, A.E. Farn, D.G. Kent, R.K. Mitchell Honorary Fellows: R.A. Howie, R.T. Liddicoat Jnr, K. Nassau Honorary Life Members: D.J. Callaghan, E.A. Jobbins, H. Tillander Council of Management: T.J. Davidson, N.W. Deeks, R.R. Harding, MJ. O'Donoghue, I. Thomson, V.R Watson Members' Council: A.J. Allnutt, P. Dwyer-Hickey, S.A. Everitt, A.G. Good, J. Greatwood, B. Jackson, J. Kessler, J. Monnickendam, L. Music, J.B. Nelson, P.G. Read, R. Shepherd, P.J. Wates, C.H. Winter Branch Chairmen: Midlands - G.M. Green, North West - L Knight, Scottish - B. Jackson Examiners: A.J. Allnutt, M.Sc, Ph.D., FGA, L. Bartlett, B.Sc, M.Phil., FGA, DGA, E.M. Bruton, FGA, DGA, S. Coelho, B.Sc, FGA, DGA, Prof. A.T. Collins, B.Sc, Ph.D, A.G. Good, FGA, DGA, J. Greatwood, FGA, G.M. Howe, FGA, DGA, G.H. Jones, B.Sc, Ph.D., FGA, M. Newton, B.Sc, D.Phil, C.J.E. Oldershaw, B.Sc (Hons), FGA, H.L. Plumb, B.Sc, FGA, DGA, R.D. ROSS, B.Sc, FGA, DGA, PA. Sadler, B.Sc, FGA, DGA, E. -
Revised Nomenclature of Högbomite, Nigerite, and Taaffeite Minerals
Eur. J. Mineral. 2002, 14, 389–395 Revised nomenclature of högbomite, nigerite, and taaffeite minerals THOMAS ARMBRUSTER Laboratorium für chemische und mineralogische Kristallographie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, e-mail: [email protected] Abstract: Minerals of the högbomite, nigerite, and taaffeite groups form polysomatic series composed of spinel (S) and nolanite (N) modules. The idealised formula of a spinel module is T2M4O8 where T and M represent tetrahedrally and octahedrally coordinated cations. The nolanite module in nigerite and högbomite minerals has the formula TM4O7(OH) whereas the nolanite module in the Be- bearing taaffeite minerals is modified (N’) and has the formula BeTM4O8. The modules are normalised to two closest-packed oxygen layers situated parallel to (001) in hexagonal setting. The composition of these minerals thus depends: (1) on the composition of the nolanite module, (2) on the composition of spinel module, (3) on the number of spinel and nolanite modules forming the structure. Högbomite- and nigerite-group minerals are distinguished by the dominant tetravalent cation in the nolanite module. If the molar concentration of Ti > Sn, the group name is högbomite. If the molar concentration of Sn > Ti, the group name is nigerite. Taaffeite- group minerals have a nolanite module without OH groups but with additional tetrahedral Be. In the new nomenclature, approved by the IMA CNMMN, the subgroup name is chosen according to the composition of the aluminium-spinel module. If the spinel module is dominated by the gahnite component, ZnAl2O4, the prefix ‘zinco’ is used. If the spinel module is dominated by the hercynite component, FeAl2O4, the prefix ‘ferro’ is used. -
The Gemmological Laboratory Book a Guide for the Management and Technical Operations of Gemmological Laboratories
© CIBJO 2016 All rights reserved GEMMOLOGICAL COMMISSION 2016 - 1 2016–1 2016-10–27 CIBJO/Laboratories CIBJO/GEMMOLOGICAL COMMISSION The Gemmological Laboratory Book A Guide for the Management and Technical Operations of Gemmological Laboratories i © CIBJO 2016 All rights reserved GEMMOLOGICAL COMMISSION 2016 — 1 Table of Contents FOREWORD ............................................................................................................................III INTRODUCTION ........................................................................................................................V 1. SCOPE............................................................................................................................. 6 2. NORMATIVE REFERENCES .................................................................................................. 6 3. TERMS AND DEFINITIONS .................................................................................................. 7 3.1. AUDIT ..................................................................................................................... 7 3.2. CALIBRATION ........................................................................................................... 7 3.3. CERTIFICATE............................................................................................................ 7 3.4. CERTIFIED REFERENCE MATERIALS — CRMS ................................................................ 7 3.5. COMPETENT SUBCONTRACTOR .................................................................................. -
Identification of Taaffeite and Musgravite Using a Non-Destructive
The Journal of Gemmology2008 / Volume 31 / Nos. 1/2 ©2004 Gemmological Association and Gem Testing Laboratory of Great Britain The Gemmological Association of Great Britain The Journal of Gemmology2008 / Volume 31 / Nos. 1/2 Contents 1 Thortveitite – a new gemstone 43 Identification of taaffeite and musgravite R. Chapman, I.F. Mercer, A.H. Rankin and using a non-destructive single-crystal J. Spratt X-ray diffraction technique with an EDXRF instrument 7 Surface treatment of gemstones, A. Abduriyim, T. Kobayashi and C. Fukuda especially topaz – an update of recent patent literature 55 Abstracts K. Schmetzer 61 Letters 15 Visualization of the internal structures of cultured pearls by computerized X-ray 62 Proceedings of The Gemmological microtomography Association of Great Britain and Notices U. Wehrmeister, H. Goetz, D.E. Jacob, A. Soldati, W. Xu, H. Duschner and W. Hofmeister 70 Obituaries 23 Specular reflectance infrared 72 Gem-A Events spectroscopy – a review and update of a little exploited method for gem identification T. Hainschwang and F. Notari 31 Afghan beryl varieties L. Natkaniec-Nowak 40 The positions of light spots on rose quartz star spheres H. Killingback Cover Picture: Faceted thortveitite in daylight (top) and incandescent light (lower right). (See Thortveitite – a new gemstone, p. 1.) The Gemmological Association of Great Britain 27 Greville Street, London EC1N 8TN T: +44 (0)20 7404 3334 F: +44 (0)20 7404 8843 E: [email protected] W: www.gem-a.com ©2004 Gemmological Association and Gem Testing Laboratory of Copyright © 2008 Designed and printed by DG3 (Europe) Ltd ISSN: 1355-4565 The Journal of Gemmology / 2008 / Volume 31 / No. -
Revised Nomenclature of Högbomite, Nigerite, and Taaffeite Minerals
Eur. J. Mineral. 2002, 14, 389–395 Revised nomenclature of högbomite, nigerite, and taaffeite minerals THOMAS ARMBRUSTER Laboratorium für chemische und mineralogische Kristallographie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, e-mail: [email protected] Abstract: Minerals of the högbomite, nigerite, and taaffeite groups form polysomatic series composed of spinel (S) and nolanite (N) modules. The idealised formula of a spinel module is T2M4O8 where T and M represent tetrahedrally and octahedrally coordinated cations. The nolanite module in nigerite and högbomite minerals has the formula TM4O7(OH) whereas the nolanite module in the Be- bearing taaffeite minerals is modified (N’) and has the formula BeTM4O8. The modules are normalised to two closest-packed oxygen layers situated parallel to (001) in hexagonal setting. The composition of these minerals thus depends: (1) on the composition of the nolanite module, (2) on the composition of spinel module, (3) on the number of spinel and nolanite modules forming the structure. Högbomite- and nigerite-group minerals are distinguished by the dominant tetravalent cation in the nolanite module. If the molar concentration of Ti > Sn, the group name is högbomite. If the molar concentration of Sn > Ti, the group name is nigerite. Taaffeite- group minerals have a nolanite module without OH groups but with additional tetrahedral Be. In the new nomenclature, approved by the IMA CNMMN, the subgroup name is chosen according to the composition of the aluminium-spinel module. If the spinel module is dominated by the gahnite component, ZnAl2O4, the prefix ‘zinco’ is used. If the spinel module is dominated by the hercynite component, FeAl2O4, the prefix ‘ferro’ is used. -
14 Non-Pegmatitic Deposits of Beryllium: Mineralogy, Geology, Phase Equilibria and Origin Mark D
14 Non-pegmatitic Deposits of Beryllium: Mineralogy, Geology, Phase Equilibria and Origin Mark D. Barton and Steven Young Center for Mineral Resources Department of Geosciences University of Arizona Tucson, Arizona 85721 [email protected] INTRODUCTION Non-pegmatitic occurrences of Be minerals constitute a diverse set of geologic environments of considerable mineralogical and petrological interest; they currently provide the majority of the world’s Be ore and emeralds and they contain the greatest resource of these commodities. Of the approximately 100 Be minerals known (see Chapter 1 by Grew; Appendix A), most occur in hydrothermal deposits or non-pegmatitic igneous rocks, where their distribution varies systematically with the setting and origin (Table 1, Fig. 1). Figure 1. Chemography of the principal solid phases in the BeO-Al2O3-SiO2-H2O(-F2O-1) “BASH” system with the projected positions of helvite group and alkali Be silicates. Also shown are generalized fields for some of the major types natural of occurrences (cf. Table 1, Fig. 4; see text for discussion). Beryllium minerals are best known from geologic systems associated with felsic magmatism. They also occur in a variety of settings that lack evident igneous associations. Environments range from the surface to the deep crust and host rocks range from feldspathic to carbonate to ultramafic in composition. Genetically related igneous rocks are felsic and share low calcium and high F contents, but are diverse in composition, setting and origin. Compositions range from strongly peraluminous to 1529-6466/02/0050-0014$10.00 DOI:10.2138/rmg.2002.50.14 592 Chapter 14: Barton & Young Table 1. -
Fall 1999 Gems & Gemology
EDITORIAL Contents The 1999 International Gemological Symposium: What a Ride! 1 Alice Keller and Kathryn Kimmel VALEDICTORY ADDRESSES Globalization and Technology: Dynamic Forces for the 21st Century 2 Maurice Tempelsman Meeting the Millennium in the Gem & Jewelry Trade 8 William E. Boyajian SPECIAL SESSION Observations on GE-Processed Diamonds: A Photographic Record 14 Thomas M. Moses, James E. Shigley, Shane F. McClure, John I. Koivula, and Mark Van Daele PHOTOMONTAGE People, Places, and Events 23 ABSTRACTS OF FEATURE PRESENTATIONS / BY SESSION DIAMOND Changes and New Developments in Africa 34 SOURCES John J. Gurney Diamonds from Australia 37 A. J. A. (Bram) Janse Canadian Diamond Production: A Government Perspective 40 Douglas Paget Russian Diamond Sources 43 N. V. Sobolev DIAMOND The New York Diamond Market 44 MANUFACTURING Hertz Hasenfeld & DISTRIBUTION The Antwerp Diamond Sector 46 Marcel Pruwer The Indian Perspective: Challenges and New Developments 47 M. A. Mitchell Diamond Manufacturing and Distribution: The Israeli Perspective 49 Shmuel Schnitzer DIAMOND The Effect of International Economic Developments ECONOMICS on the Diamond Market 50 Carl Pearson Diamond Economics: A Dynamic Analysis 51 Martin Rapaport The Diamond Distribution System 52 Eli Haas Retail Markets and the Growing Global Significance of Branding 53 Russell Shor PERSPECTIVES A Manufacturer's Perspective 55 ON THE DIAMOND Sean Cohen MARKET The U.S. Diamond Industry 56 Benjamin Janowski Today and Tomorrow in the Japanese Jewelry Market 58 Hidetaka Kato The Developing Market in China 59 Gerald L. S. Rothschild i COLORED STONE Ruby and Sapphire Occurrences Around the World 60 SOURCES Robert E. Kane Emeralds—Recent Developments and Projected Changes in Supply 62 Dietmar Schwarz Review of Gem Localities in North America, Russia, and Southeast Asia 64 William Larson Colored Stone Sources in Africa and Madagascar 66 Abe K. -
Mineral Names, Redefinitions & Discreditations Passed by the CNMMN of The
9 February 2004 – Note to our readers: We welcome your comments and criticism. If you are reporting substantive changes, errors or omissions, please provide us with a literature reference so we can confirm what you have suggested. Thanks! Mineral Names, Redefinitions & Discreditations Passed by the CNMMN of the IMA Ernie Nickel & Monte Nichols [email protected] & [email protected] Aleph Enterprises PO Box 213 Livermore, California 94551 USA This list contains minerals derived from the Materials Data, Inc. MINERAL Database and was produced expressly for the use of the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA). All rights to the use of the data presented here, either printed or electronic, rest with Materials Data, Inc. Minerals presented include those voted as “approved” (A), “redefined or renamed” (R) and “discredited” (D) species by the CNMMN as well as a number of former mineral names the CNMMN decided would better be used as group names (g). Their abbreviated symbol appears at the left margin. Minerals in the MINERAL Database which have been designated as “Q” (questionable minerals, not approved by the CNMMN), as “G” (“golden or grandfathered” minerals described in the past and generally believed to represent valid species names), as “U” (unnamed), as “N” (not approved by the CNMMN) and as “P” (polymorphs) have not been included as part of this listing. These minerals can be found in the Free MINERAL Database now being distributed by Materials Data, Inc ([email protected] and http://www.materialsdata.com) for just the cost of making and shipping the CD or without any cost whatever when downloaded directly from the Materials Data website. -
Distinction of Taaffeite and Musgravite
The Journal of Gemmology Volume 26 No. 3 July 1998 The Gemmological Association and Gem Testing Laboratory of Great Britain Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London EC1N 8SU Tel: 0171 404 3334 Fax: 0171 404 8843 e-mail: [email protected] Website: www.gagtl.ac.uk/gagtl President: Professor R.A. Howie Vice-Presidents: E.M. Bruton, A.E. Farn, D.G. Kent, R.K. Mitchell Honorary Fellows: R.A. Howie, R.T. Liddicoat Jnr, K. Nassau Honorary Life Members: D.J. Callaghan, E.A. Jobbins, H. Tillander Council of Management: C.R. Cavey, T.J. Davidson, N.W. Deeks, R.R. Harding, I. Thomson, V.P. Watson Members' Council: A.J. Allnutt, P. Dwyer-Hickey, S.A. Everitt, R. Fuller, A.G. Good, J. Greatwood, B. Jackson, J. Kessler, J. Monnickendam, L. Music, J.B. Nelson, P.G. Read, R. Shepherd, P.J. Wates, C.H. Winter Branch Chairmen: Midlands - G.M. Green, North West - I. Knight, Scottish - B. Jackson Examiners: A.J. Allnutt, M.Sc., Ph.D., FGA, S.M. Anderson, B.Sc. (Hons), FGA, L. Bartlett, B.Sc., MPhil., FGA, DGA, E.M. Bruton, FGA, DGA, C.R. Cavey, FGA, S. Coelho, B.Sc., FGA, DGA, Prof. A.T. Collins, B.Sc., Ph.D, A.G. Good, FGA, DGA, G.M. Howe, FGA, DGA, G.H. Jones, B.Sc., Ph.D., FGA, M. Newton, B.Sc., D.Phil., CJ.E. Oldershaw, B.Sc. (Hons), FGA, H.L. Plumb, B.Sc., FGA, DGA, R.D. Ross, B.Sc., FGA, DGA, P.A. -
Polysomatism in Högbomite: the Crystal Structures of 10T, 12H, 14T, and 24R Polysomes
American Mineralogist, Volume 87, pages 277–292, 2002 Polysomatism in högbomite: The crystal structures of 10T, 12H, 14T, and 24R polysomes CLIVIA HEJNY AND THOMAS ARMBRUSTER* Laboratorium für chemische und mineralogische Kristallographie, Universität Bern, Freiestr. 3, CH-3012 Bern, Switzerland ABSTRACT Högbomite is a closest-packed polysomatic mineral composed of spinel, T2M4O8, and nolanite- like, TM4O7(OH), modules where T stands for tetrahedrally and M for octahedrally coordinated cations. The modules are stacked in an ordered fashion in various ratios. Single-crystal X-ray dif- fraction for a 24R and a 10T polysome and structure modeling for a 12H and 14T polysome have been applied to characterize different stacking variants. Högbomite from a spinel-phlogopite schist at Corundum Creek (South Australia) with composi- tion Mg Fe Zn Ti Al O (OH) is a 10T polysome with a = 5.723(1), c = 23.026(4) Å, space 3.8– 3.2 1.6 1.0 18.3 38 2 group P3m1, Z = 1. This polysome with the general formula T8M20O38(OH)2 is composed of an alternation of spinel (S) and nolanite-like (N) blocks stacked in the sequence NSSNS. Högbomite from a Fe-Ti deposit at Liganga (Tanzania) with composition Mg Fe (Zn,Mn,Ni) 13.5 5.6 – 0.2 Ti4.7Al41.7(Cr,Ga)0.2O90(OH)6 is a 24R polysome with a = 5.7145(7), c = 55.056(5) Å, space group R3m, Z = 1. The structure with the general formula T18M48O90(OH)6 is composed of a periodic alternation of two S and two N blocks. -
Twinning and Epitaxial Growth of Taaffeite-Type Modulated Structures
CrystEngComm View Article Online PAPER View Journal | View Issue Twinning and epitaxial growth of taaffeite-type modulated structures in BeO-doped MgAl2O43 Cite this: CrystEngComm, 2013, 15, 2640 Sandra Drev, Aleksander Recˇnik and Nina Daneu A recent study of (111) twins in MgAl2O4 spinel crystals from Mogok (Burma) implied that twinning could be triggered by the presence of Be during crystal growth. Here we demonstrate that twinning in spinel is in fact chemically induced and is not a consequence of an accidental attachment of crystals. The growth conditions were reproduced in a tube furnace at 1200 uC by liquid-phase assisted reaction of Al2O3 and MgO with the addition of BeO, while PbF2 was used as melt-forming agent. BeO does not only cause abundant {111} twinning of spinel, but also complex topotaxial overgrowths of BeMg3Al8O16 taaffeite when the concentration of BeO exceeds 12.5 mol%. A HRTEM study of the spinel–taaffeite interface confirmed the following epitaxial relationship: [11¯0]?{111}spI[112¯0]?{0001}taf. The basic structural unit, observed on (111) twin boundary in spinel (i.e. Be2+ replacing for Mg2+ on the interfacial tetrahedral interstices), is identical to hexagonal close-packed (hcp) sequences observed in ternary taaffeite Received 10th December 2012, compounds, suggesting that twinning is probably a preparatory stage of polytype formation. The Accepted 18th January 2013 formation {111} twins in spinel is explained in the context of twin-induced exaggerated grain growth DOI: 10.1039/c3ce26997c mechanism. This phenomenon can be exploited for the production of spinel crystals with complex www.rsc.org/crystengcomm morphologies. -
Journal Vol 31 No1 2 2008 Final.Indd
The Journal of Gemmology2008 / Volume 31 / Nos. 1/2 The Journal of Gemmology 2008 / Volume 31 / Nos 1/2 / pp 1 72 ©2004 Gemmological Association and Gem Testing Laboratory of Great Britain The Gemmological Association of Great Britain The Journal of Gemmology / 2008 / Volume 31 / No. 1/2 The Gemmological Association of Great Britain 27 Greville Street, London EC1N 8TN T: +44 (0)20 7404 3334 F: +44 (0)20 7404 8843 E: [email protected] W: www.gem-a.com Registered Charity No. 1109555 Registered offi ce: Palladium House, 1-4 Argyll Street, London W1F 7LD President: E. A. Jobbins Vice-Presidents: N. W. Deeks, R. A. Howie Honorary Fellows: R. A. Howie, K. Nassau Honorary Life Members: H. Bank, D. J. Callaghan, E. A. Jobbins, J. I. Koivula, C. M. Ou Yang, I. Thomson, V. P. Watson, C. H. Winter Chief Executive Offi cer: J. M. Ogden Council: A. T. Collins – Chairman, T. M. J. Davidson, M. J. O’Donoghue, J. Riley, E. Stern, J. F. Williams Members’ Audit Committee: A. J. Allnutt, J. W. Collingridge, P. Dwyer-Hickey, J. Greatwood, G. M. Green, B. Jackson, D. J. Lancaster Branch Chairmen: Midlands – P. Phillips, North East – M. Houghton, North West – D. M. Brady, Scottish – B. Jackson, South East – V. Wetten, South West – R. M. Slater The Journal of Gemmology Editor: Dr R. R. Harding Assistant Editors: M. J. O’Donoghue, P. G. Read Associate Editors: A. J. Allnutt (Chislehurst), Dr C. E. S. Arps (Leiden), G. Bosshart (Horgen), Prof. A. T. Collins (London), J. Finlayson (Stoke on Trent), Dr J.