DOCSLIB.ORG

Gemmology Volume 26 No

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

The Journal of Gemmology Volume 26 No. 2 April 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: 01714043334 Fax: 01714048843 e-mail: [email protected] Website: www.gagtl.ac.uk/gagtl President: Professor RA Howie Vice-Presidents: E.M. Bruton, AE. Faro, D.G. Kent, RK. Mitchell Honorary Fellows: RA Howie, R.T. Liddicoat Jill, K. Nassau Honorary Life Members: D.J. Callaghan, E.A Jobbins, H. Tillander Council of Management: CR Cavey, T.J. Davidson, N.W.. Deeks, RR Harding, I. Thomson, V.P. Watson Members' Council: AJ. Allnutt, P. Dwyer-Hickey, R Fuller, J. Greatwood, B. Jackson, J. Kessler, J. Monhickendam, 1. Music, J.B. Nelson, P.G. Read, R Shepherd, CH. Winter Branch Chairmen: Midlands ~ G.M. Green, North West -I. Knight, Scottish - B. Jackson Examiners: AJ. Allnutt, M.5c., Ph.D., FGA, S.M. Anderson, B.Sc. (Hons), FGA, 1. Bartlett, B.Sc., M.Pbil., FGA, DGA, E.M. Bruton, FGA, DGA, CR Cavey, .FGA, S. Coelho, B.Sc., FGA, DGA, Prof. AT. Collins, B.Sc., Ph.D, AG. Good, FGA, DGA, CJ.E. Hall, B.Sc. (Hons), FGA, G.M .. Howe, FGA, DGA, G.H. Jones, B.5c., Ph.D., FGA, M. Newton, B.Sc., D.Phil.,H.1. Plumb, B.Sc., FGA, DGA, RD. Ross, B.Sc., FGA, DCA, P.A Sadler, B.5c., FCA, DCA, E. Stern, FGA, DGA, P rof. I. Sunagawa, D.5c., M. Tilley, GG, FGA, CM. Woodward, B.Sc .., FGA, DGA The Journal of Gemmology Editor: Dr RR Harding Assistant Editors: M.J. O'Donoghue, P.G. Read Associate Editors: S.M. Anderson (London), Dr CE.s. Arps (Leiden), G. Bosshart (Zurich), Prof. AT. Collins (London), Dr J.w. Harris (Glasgow), Prof. RA Howie (Derbyshire), Dr J.M. Ogden (Cambridge), Prof. AH. Rankin (Kingston upon Thames), Dr J.E. Shigley (Carlsbad), Prof. D.C Smith (Paris), E. Stern (London), Prof. I. Sunagawa (Tokyo), Dr M. Superchi (Milan), CM. Woodward (London) Production Editor: M.A Burland Vol 26. No.2, April 1998 ISSN: 1355-4565 Distinctive gem corundum suites from discrete basalt fields: a comparative study of Barrington, Australia, and West Pailin, Cambodia, gemfields F.L. Sutherland1, D. Schwarz2, E.A. Jobbins3, R.R. Coenraads1 and G. Webb1 1. Geodiversity Research Group, Australian Museum, Sydney, Australia 2. Giibelin Gemmological Laboratory, Lucerne, Switzerland 3. Caterham, Surrey, U.K. ABSTRACT: Barrington, Australia, and West Pailin, Cambodia, basalt fields yield remarkably similar 'metamorphic' corundums (including ruby) and 'basaltic' type blue corundums. These represent different underlying sources tapped by basaltic eruptions. The 'metamorphic' suites have high chromium/low gallium chemistry, with Ga203 contents <0.01 wt% and Cr203/Ga203 ratios above 3. The 'basaltic' suites show higher Ga203 (up to 0.04 wt%) and Cr203/Ga203 ratios below 1. The 65 absorption spectra of blue 'metamorphic' sapphires are dominated by Fe3+ bands in the ultraviolet (375, 387 nm) and visible region (450, 460, 469 nm). A broad Fe2+ - Ti4+ charge transfer band lies between 550-750 nm, without significant Fe2+ - Fe3+ charge transfer absorption toward the near infrared that is typical of blue 'basaltic' sapphires. Most absorption spectra of 'metamorphic' corundums represent a combination of Fe/Ti/Cr-bands, with variable relative intensities. Keywords: corundum, sapphire, ruby, sapphirine, absorption spectra, trace elements, basalt, Barrington (Australia), Pailin (Cambodia) Introduction widely separated basalt fields, Barrington in Fast Australia and South East Asia East Australia and West Pailin in Cambodia, exploit rich corundum deposits from and show that they contain mixed ruby and • / their basalt fields, in significant mining, sapphire suites of remarkable similarity. processing and cutting industries (Mumme, Two distinctive gem corundum suites 1988; Hughes, 1990, 1997). East Australia appear in eluvial and alluvial deposits produces sapphire and rare ruby (Coldham, from the Barrington basalt province in 1985; Olliver and Townsend, 1990; Sutherland, New South Wales, one typical of East 1991), while SE Asia produces both sapphire Australian sapphire fields and the other and ruby in abundance (Vichit, 1992). In this associated with rubies (Sutherland and paper we describe corundum suites from two Coenraads, 1996). Besides typical Australian © Gemmological Association and Gem Testing Laboratory of Great Britain ISSN: 1355-4565 corrodedcorroded blue-green-yelloblue-green-yelloww zonedzoned sapphiressapphires PreliminaryPreliminary examinationexamination ooff WesWestt PailiPailinn (Coenraads,(Coenraads, 1992a,1992a, b;b; Sutherland,Sutherland, 1996;1996; GuoGuo etet materiamateriall showedshowed itsits similaritysimilarity ttoo thethe al.,al, 1996),1996), ththee BarringtonBarrington provinceprovince alsoalso yieldyieldss BarringtoBarringtonn suites,suites, includingincluding sapphirinesapphirine aass anan anan abundantabundant pastel-colouredpastel-coloured sapphire-rubysapphire-ruby intergrowthintergrowth inin thethe rubyruby associationassociation (analysis(analysis suitesuite (Sutherland(Sutherland et al.,al, 1993;1993; SutherlandSutherland andand bbyy K.K. Williams).Williams). A mormoree detaileddetailed Coenraads,Coenraads, 1996).1996). RecognitionRecognition ofof thisthis lastlast suitesuite investigationinvestigation ofof samplessamples collectedcollected bbyy JobbinsJobbins promptedprompted a re-examinatiore-examinationn ofof rubyruby andand waswas carriedcarried outout bbyy personnepersonnell frofromm thethe sapphiresapphire collectedcollected fromfrom basaltbasalt fieldsfields aroundaround AustraliaAustraliann MuseumMuseum anandd GiibelinGiibelin PailiPailinn bbyy E.A.E.A. JobbinsJobbins inin 19741974 (Berrange(Berrangé andand GemmologicalGemmological Laboratory,Laboratory, Switzerland.Switzerland. ThisThis JobbinsJobbins,, 1976;1976; JobbinsJobbins andand Berrange,Berrangé, 1981).1981). worworkk includesincludes gemmologicalgemmological studiestudiess onon Figure 1: Distribution ofof basaltic basaltic rocks rocks (stippled (stippled areas) areas) and mainand maindrainages, drainages, Barrington Barrington volcano volcano province, 250 250 km km north north of ofSydney, Sydney, New New South South Wales. Wales. Corundum/zircon Corundum/zircon suites suitesare marked are marked by inclined by inclined crosses. The The numbered numbered sites sites are are basalt basalt age-dating age-dating sites, sites,with thewith following the following ages, 1: ages, 44-54 1: m.y., 44-54 1A: m.y., 1A: 54 m.y.,m.y., 2:2: 3737 m.y.,m.y., 2A:2A: 4242 m.y., m.y., 3: 3: 52-54 52-54 m.y., m.y., 4: 4: 59 59 m.y., m.y., 5: 5: 54 54 m.y. m.y. (based (based on onSutherland Sutherland and and Fanning, 1996). 1996). The The main main intrusive intrusive centre centre of Barrington of Barrington volcano volcano is marked is markedby a triangle by a (1555triangle m above (1555 m above sea level) andand the the original original extent extent of ofthe the volcano volcano before before dissection dissection is marked is marked by a dashed by a dashedperimeter perimeter (600-800 m m a.s.l.), a.s.L), after after Pain, Pain, 1983. 1983. 66 66 J.J . Gemm., 1998, 1998,26,2, 26, 2, 65-85 65-85 3km j N 67 67 Figure 2: Distribution of basaltic rocks (denser stippled areas) and drainages, Pailin district,district, Cambodia.Cambodia . Gem-bearing drainage is shown as continuous lines, with gem-barren drainages shown as short dashed lines. Volcanic ventsvents areare indicatedindicated byby trianglestriangles andand thethe mainmain basaltbasalt centrescentres areare PhnumPhnum KoKo Ngoap, Phnum 0O Tang forfor dominant fancyfancy coloured corundums, and Phnum Yat forfor dominant 'basaltic''basaltic' blueblue corundums. The main drainages are the O0 Chra and Stoeng Pailin rivers and the road toto Pailin is marked by a double line.line. The geological boundaryboundary betweenbetween youngeryounger basementbasement rocksrocks (coarse(coarse stipple) and older crystalline basement (unmarked) isis shown by a heavy line,line, and fault zones are markedmarked by long dashes.dashes. Diagram modified fromfrom BerrangéBerrange and Jobbins, 1976, and Jobbins andand Berrange,Berrangé, 1981.1981. corunducorundumm frofromm BarringtoBarringtonn anandd WesWestt PailiPallinn (CAMEC(CAMECAA microprobmicroprobee witwithh WDWDSS spectrospectro­­ anandd comparativcomparativee studiestudiess oonn sapphiresapphiress fromfrom metermeter;; R.RRR.. CoenraadsCoenraads,, F.LF.L.. SutherlandSutherland)) anandd EasEastt AustraliaAustralia,, frofromm centracentrall QueenslandQueensland comparisoncomparisonss ooff ththee corunducorundumm suitesuitess iinn (Anaki(Anakiee FieldsFields)) anandd NeNeww SoutSouthh WaleWaless discussiodiscussionn ooff theitheirr geologicageologicall originoriginss (Ne(Neww EnglanEnglandd FieldsFields)) anandd frofromm EasEastt PailinPallin.. (F.L(F.L.. Sutherland,Sutherland, D.D. Schwarz).Schwarz). StudieStudiess includincludee photographphotographyy anandd photophoto­­ micrography (G. Webb, E.A. Jobbins), trace micrography (G. Webb, E.A. Jobbins), trace GeologicaGeologicall settingsettingss elemenelementt anandd coloucolourr absorptioabsorptionn spectraspectrall studiestudiess (EDXRF(EDXRF,, UV-vis-NIUV-vis-NIRR spectrometry;spectrometry; ThThee BarringtoBarringtonn corundumcorundumss comcomee frofromm ththee DD.. Schwarz)Schwarz),, chemicachemicall analyseanalysess ooff inclusioninclusionss erodeerodedd BarringtoBarringtonn shielshieldd volcanvolcanoo iinn anandd intergrowthintergrowthss iinn WesWestt PailiPallinn corundumscorundums NeNeww SoutSouthh WaleWaless
Recommended publications
  • Polychrome: Qualitative Palettes with Many Colors

    Polychrome: Qualitative Palettes with Many Colors

    Package ‘Polychrome’ July 16, 2021 Title Qualitative Palettes with Many Colors Version 1.3.1 Date 2021-07-16 Author Kevin R. Coombes, Guy Brock Description Tools for creating, viewing, and assessing qualitative palettes with many (20-30 or more) colors. See Coombes and colleagues (2019) <doi:10.18637/jss.v090.c01>. Maintainer Kevin R. Coombes <[email protected]> Depends R (>= 3.5.0) Imports colorspace, scatterplot3d, methods, graphics, grDevices, stats, utils Suggests RColorBrewer, knitr, rmarkdown, ggplot2 License Apache License (== 2.0) LazyLoad yes LazyData no URL http://oompa.r-forge.r-project.org/ VignetteBuilder knitr NeedsCompilation no Repository CRAN Date/Publication 2021-07-16 15:20:02 UTC R topics documented: alphabet . .2 colorDeficit . .3 colorsafe . .4 createPalette . .5 Dark24 . .6 distances . .7 getLUV . .8 1 2 alphabet glasbey . .9 invertColors . 10 iscc ............................................. 11 isccNames . 12 memberPlot . 13 palette.viewers . 14 palette36 . 16 palettes . 16 sky-colors . 18 sortByHue . 19 Index 21 alphabet A 26-Color Palette Description A palette composed of 26 distinctive colors with names corresponding to letters of the alphabet. Usage data(alphabet) Format A character string of length 26. Details A character vector containing hexadecimal color representations of 26 distinctive colors that are well separated in the CIE L*u*v* color space. Source The color palette was generated using the createPalette function with three seed colors: ebony ("#5A5156"), iron ("#E4E1E3"), and red ("#F6222E"). The colors were then manually assigned names begining with different letters of the English alphabet. See Also createPalette Examples data(alphabet) alphabet colorDeficit 3 colorDeficit Converting Colors to Illustrate Color Deficient Vision Description Function to convert any palette to one that illustrates how it would appear to a person with a color deficit.
  • Palomar Gem & Mineral Club Newsletter

    Palomar Gem & Mineral Club Newsletter

    Palomar Gem & Mineral Club Newsletter August 2016 Volume 57 Issue 07 PGMC Annual Picnic We had our annual summer picnic last month at Jesmond Dene Park. As always Moni did a fine job of coordinating the event which included great food brought by everyone as well as a good time of comparing the fine rocks and gems we have found. We had a great slab swap between our members and everyone seemed to have a good time. As summer ends and we get ready to ramp up again, we hope everyone had a safe and productive summer. August is usually a down month for PGMC so that any specialty classes can take place at the shop and folks can go on vacation. We look forward to seeing everyone at the September meeting. Check out the rest of the newsletter for more information about September’s meeting as well as upcoming class schedules. We begin classes this week! 1 Textured Metal Class Come and join in the fun, learning to texture metal and make one-of-kind earrings (3 to 4 pairs) or a bracelet). They are great gifts. You may also learn how to make your own ear wires. Instructors: Diane Hall & Annie Heffner Location: Club Shop Dates: November 20, 2016 Time: 10am-4pm Fee: $35 plus supply cost (club membership required - $25 fee for single membership). You will need about 1 ounce of silver or copper sheet, which we will purchase for every one who is signed up by November 11th. Sign ups after that will need to provide their own material.
  • The Wittelsbach-Graff and Hope Diamonds: Not Cut from the Same Rough

    The Wittelsbach-Graff and Hope Diamonds: Not Cut from the Same Rough

    THE WITTELSBACH-GRAFF AND HOPE DIAMONDS: NOT CUT FROM THE SAME ROUGH Eloïse Gaillou, Wuyi Wang, Jeffrey E. Post, John M. King, James E. Butler, Alan T. Collins, and Thomas M. Moses Two historic blue diamonds, the Hope and the Wittelsbach-Graff, appeared together for the first time at the Smithsonian Institution in 2010. Both diamonds were apparently purchased in India in the 17th century and later belonged to European royalty. In addition to the parallels in their histo- ries, their comparable color and bright, long-lasting orange-red phosphorescence have led to speculation that these two diamonds might have come from the same piece of rough. Although the diamonds are similar spectroscopically, their dislocation patterns observed with the DiamondView differ in scale and texture, and they do not show the same internal strain features. The results indicate that the two diamonds did not originate from the same crystal, though they likely experienced similar geologic histories. he earliest records of the famous Hope and Adornment (Toison d’Or de la Parure de Couleur) in Wittelsbach-Graff diamonds (figure 1) show 1749, but was stolen in 1792 during the French T them in the possession of prominent Revolution. Twenty years later, a 45.52 ct blue dia- European royal families in the mid-17th century. mond appeared for sale in London and eventually They were undoubtedly mined in India, the world’s became part of the collection of Henry Philip Hope. only commercial source of diamonds at that time. Recent computer modeling studies have established The original ancestor of the Hope diamond was that the Hope diamond was cut from the French an approximately 115 ct stone (the Tavernier Blue) Blue, presumably to disguise its identity after the that Jean-Baptiste Tavernier sold to Louis XIV of theft (Attaway, 2005; Farges et al., 2009; Sucher et France in 1668.
  • Federal Wage System Glossary of Printing Terms for the 4400 Job Family

    Federal Wage System Glossary of Printing Terms for the 4400 Job Family

    Glossary of Printing Terms for the 4400 Job Family TS-45 October 1981 Federal Wage System Glossary of Printing Terms for the 4400 Job Family The terms and definitions contained in this glossary are intended to facilitate the application of published job grading standards to occupations in the Printing Family. The glossary does not represent a comprehensive listing of technical terms and processes common to printing occupations. Additional information may be found in dictionaries, and technical publications such as agency guides, trade magazines, and technical manuals. Aluminum Plate. A thin sheet of aluminum used in lithography for some press plates; image applied photographically; used for both surface-type and deep-etch offset plates. Aperture. A small opening in a plate or sheet. In cameras, the aperture is usually variable in the form of an iris diaphragm and regulates the amount of light which passes through the lens. The working aperture is the diameter of that part of the lens actually used. Asphaltum. A bituminous mixture used as an acid resist or protectant in photomechanics. In lithography, used to make printing image on press plate permanently ink-receptive. Autoscreen (Film). A photographic film embodying the halftone screen; exposed to a continuous-tone image, produces a dot pattern automatically just as if a halftone screen had been used in the camera. Backing-Up. Printing the other side, of a printed sheet. Back Pressure. The squeeze pressure between the blanket (offset) cylinder and the impression cylinder; sometimes called "impression pressure." Base Color. A first color used as a background on which other colors are printed.
  • A Survey of the Gemstone Resources of China

    A Survey of the Gemstone Resources of China

    A SURVEY OF THE GEMSTONE RESOURCES OF CHINA By Peter C. Keller and Wang Fuquan The People's Republic of China has recently hina has historically been a land of great mystery, placed a high priority on identifying and C with natural resources and cultural treasures that, developing its gemstone resources. Initial until recently, were almost entirely hidden from the out- exploration by teams of geologists side world. From the point of view of the geologist and throughout China has identified many gemologist, one could only look at known geological maps deposits with significant potential, of this huge country and speculate on the potential impact including amher, cinnabar, garnets, blue sapphires, and diamonds. Small amounts of China would have on the world's gem markets if its gem ruby have' qlso been found. Major deposits resources were ever developed to their full potential. of nephriteyade as well as large numbers of During the past few years, the government of the Peo- gem-bearing pegmatite dilces have been ple's Republic of China (P.R.C.)has opened its doors to the identified.Significant deposits of peridot outside world in a quest for information and a desire for are crirrently being exploited from Hebei scientific and cultural cooperation. It was in this spirit of Province. Lastly, turqrloise rivaling the cooperation that a week-long series of lectures on gem- finest Persian material has been found in stones and their origins was presented by the senior author large quantities in Hubei and Shaanxi and a colleague to over 100 geologists from all over China Provinces.
  • Historic Ceramics

    Historic Ceramics

    TEXAS HISTORICAL COMMISSION A STEWARD’S ILLUSTRATED KEY TO HISTORIC CERAMICS REVISED EDITION, 2006* *This guide is a revision of “A Steward’s Key to Historic Ceramics,” prepared by Dan Potter, Roland Pantermuehl and Anne Fox, in support of the 1997 Texas Archeological Stewardship Network workshop training segment entitled “Understanding Historic Period Artifact Assemblages,” conducted by Anne Fox, Center for Archaeological Research, The University of Texas at San Antonio MAJOLICA TEXAS HISTORICAL COMMISSION Unnamed Early 19th century Majolicas Guanajuato Polychrome Age Range: 1830+ (Mexico/New Spain origin) Age Range: 1790 - 1830 The colors are the key, especially the orange San Augustine Blue-on-white Age Range: 1700 - 1730 Has pale blue loops on the reverse side. Tumacacori II Polychrome Age Range: 1810 - 1840 Monterey Polychrome Age Range: 1790 - 1830 Occurs late at the San Antonio missions Tumacacori III Polychrome Age Range: 1830 - 1860 MAJOLICA (cont.) TEXAS HISTORICAL COMMISSION Faience Ware (French origin) Puebla Blue-on-White (Mexico/New Spain origin) Age Range: 18th century Age Range: 1675 - 1800; Most common Spanish Colonial type in Texas. Puebla Blue-on-White Early 18th century San Elizario (Mexico/New Spain origin) Age Range: 1750 - 1800 Huejotzingo Brown/black accents on Puebla Blue-on-White 18th century Puebla Blue White-cup Early 18th century Puebla Blue-on-White II Late 18th century San Luis Polychrome Puebla Blue-on-White Age Range: Early 18th century 1666 - 1720 (possible Mexico City origin) Puebla Blue-on-White Early
  • Smithsonian Miscellaneous Collections

    Smithsonian Miscellaneous Collections

    SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 97. NUMBER 1 PRELIMINARY REPORT ON THE SMITHSONIAN INSTITUTION-HARVARD UNIVERSITY ARCHEOLOGICAL EXPEDITION TO NORTHWESTERN HONDURAS, 1936 (With 16 Plates) BY WILLIAM DUNCAN STRONG Anthropologist, Bureau of American Ethnology ALFRED KIDDER II Peabody Museum, Harvard University AND A. J. DREXEL PAUL, JR. Peabody Museum, Harvard University (Publication 344S) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION JANUARY 17, 1938 ^'ytk w •, bo a. -x: tn>: .S U I- rt y ll < t^ z in tn LJ u IT Q. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 97, NUMBER 1 PRELIMINARY REPORT ON THE SMITHSONIAN INSTITUTION-HARVARD UNIVERSITY ARCHEOLOGICAL EXPEDITION TO NORTHWESTERN HONDURAS, 1936 (With 16 Plates) BY WILLIAM DUNCAN STRONG Anthropologist, Bureau of American Ethnology ALFRED KIDDER II Peabody Museum, Harvard University AND A. J. DREXEL PAUL, JR. Peabody Museum, Harvard University (PUBLICATIOK 3445) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION JANUARY 17, 1938 BALTIMORE, UD., U. B, A. CONTENTS PAGE Introduction i Brief geographic setting 2 Ethnic and linguistic background 8 Early historic contacts in northwestern Honduras 19 Archeological explorations 27 Chamelecon River 27 Naco 27 Las Vegas 34 Tres Piedras 35 Other sites 2>7 Ulua and Comayagua Rivers 39 Las Flores Bolsa 39 Santa Rita (farm 17 ) 45 Playa de los Muertos (farm 11) 62 Other sites 76 North end of Lake Yojoa 76 Aguacate and Aguatal 80 La Ceiba 90 Site I 91 Site 2 94 Site 3 99 Causeway and " canal " near Jaral 100 Pyramids and stone statues near Los Naranjos 102 Excavations on the northern border of Los Naranjos 105 The older horizon at Los Naranjos iii Other sites 115 Summary and tentative conclusions 118 Literature cited 125 Explanation of plates 127 ILLUSTRATIONS PLATES PAGE 1.
  • Spring 1995 Gems & Gemology

    Spring 1995 Gems & Gemology

    TABLE CONTENTS FEATURE ARTICLES 2 Rubies from Mong Hsu Adolf Pelsetti, I(ar7 Schmetzer, Heinz-Jiirgen Bernhardt, and Fred Mouawad " 28 The Yogo Sapphire Deposit Keith A. ~~chaluk NOTES AND NEW TECHNIQUES 42 Meerschaum from Eskisehir Province, Turkey I<adir Sariiz and Islcender Isilc REGULAR FEATURES 52 Gem Trade Lab Notes Gem News Most Valuable Article Award Gems ed Gemology Challenge Book Reviews Gemological Abstracts Guidelines for Authors ABOUT THE COVER: One of the most important ruby localities of the 1990s cov- ers a broad orea near the town of Mong Hsu, in northeastern Myann~ar(B~lrrna). The distinctive gemological features of these rubies are detailed in this issue's lead article. The suite of fine jewelry illustraled here contains 36 Mong Hsu rubies with a total weigh1 of 65.90 ct; the two rubies in the ring total 5.23 ct. jewelry courtesy of Mouawad jewellers. Photo by Opass Sultsumboon-Opass Suksuniboon Studio, Bangltolz, Thailand. Typesetting for Gerrls eS Gemology is by Graphix Express, Santa Monica, CA. Color separations are by Effective Graphics, Compton, CA. Printing is by Cadmus lournal Services, Easton, MD. 0 1995 Gemological Institute of America All rights reserved ISSN 0016-626X - Editor-in-Chief Editor Editors, Gem Trade Lab Notes Richard T. Lidtlicoat Alicc S. I<cller Robcrt C. I<ammerling 1660 Stewart St. C. W. Fryer Associate Editors Smta Mon~ca,CA 90404 William E. Boyajian Editors, Gem News (800)421-7250 ~251 Robcrt C. Kamn~erling Rohcrt C. I<ammerling e-mail: altellcrBclass.org D. Vincent Manson John I. Koivula John Sinltanltas Sr~bscriptions Enirnanuel Fritsch Jln Ll~n Editors, Book llevielvs Technical Editor (800) 421-7250 x201 Susan B.
  • Gemstones by Donald W

    Gemstones by Donald W

    GEMSTONES By Donald W. olson Domestic survey data and tables were prepared by Nicholas A. Muniz, statistical assistant, and the world production table was prepared by Glenn J. Wallace, international data coordinator. In this report, the terms “gem” and “gemstone” mean any gemstones and on the cutting and polishing of large diamond mineral or organic material (such as amber, pearl, petrified wood, stones. Industry employment is estimated to range from 1,000 to and shell) used for personal adornment, display, or object of art ,500 workers (U.S. International Trade Commission, 1997, p. 1). because it possesses beauty, durability, and rarity. Of more than Most natural gemstone producers in the United states 4,000 mineral species, only about 100 possess all these attributes and are small businesses that are widely dispersed and operate are considered to be gemstones. Silicates other than quartz are the independently. the small producers probably have an average largest group of gemstones; oxides and quartz are the second largest of less than three employees, including those who only work (table 1). Gemstones are subdivided into diamond and colored part time. the number of gemstone mines operating from gemstones, which in this report designates all natural nondiamond year to year fluctuates because the uncertainty associated with gems. In addition, laboratory-created gemstones, cultured pearls, the discovery and marketing of gem-quality minerals makes and gemstone simulants are discussed but are treated separately it difficult to obtain financing for developing and sustaining from natural gemstones (table 2). Trade data in this report are economically viable deposits (U.S.
  • PERIDOT from TANZANIA by Carol M

    PERIDOT from TANZANIA by Carol M

    PERIDOT FROM TANZANIA By Carol M. Stockton and D. Vincent Manson Peridot from a new locality, Tanzania, is described Duplex I1 refractometer and sodium light, approx- and compared with 13 other peridots from various imate a = 1.650, B = 1.658, and -y = 1.684, indi- localities in terms of color and chemical com- cating a biaxial positive optic character. The position. The Tanzanian specimen is lower in iron specific gravity, measured hydrostatically, is ap- content than all but the Norwegian peridots and is proximately 3.25. very similar to material from Zabargad, Egypt. A gem-quality enstatite that came from the same area CHEMISTRY in East Africa and with which Tanzanian peridot has been confused is also described. The Tanzanian peridot was analyzed using a MAC electron microprobe at an operating voltage of 15 KeV and beam current of 0.05 PA. The standards used were periclase for MgO, kyanite for Ala, quartz for SiOz, wollastonite for CaO, rutile for In September 1982, Dr. Horst Krupp, of Idar- TiOa, chromic oxide for CraOg, almandine-spes- Oberstein, sent GIA's Department of Research a sartine garnet for MnO, fayalite for FeO, and nickel sample of peridot for study. The stone was from oxide for NiO. The data were corrected using the a parcel that supposedly contained enstatite pur- Ultimate correction program (Chodos et al., 1973). chased from the Tanzanian State Gem Corpora- For purposes of comparison, we also selected tion, the source of a previous lot of enstatite that and analyzed peridots from major known locali- Dr. Krupp had already cut and marketed.
  • Olivine – Peridot 橄欖石 Prof

    Olivine – Peridot 橄欖石 Prof

    Olivine – Peridot 橄欖石 Prof. Dr H.A. Hänni, FGA, SSEF Research Associate Email: [email protected] Fig. 1 Peridots rough and cut, from various locations. Photo © H.A.Hänni 作者述了寶石級橄欖石的特性，它歸屬於橄欖石 類礦物，它有三種成因，化學成的改變而引致顏 色、折射率和比重的變異，並簡報其內含物、人工 合成方法和產地，以及作為首飾時應注意的地方。 Peridot is a widely appreciated green gemstone (Fig. 1). It belongs to the Olivine group, which also includes the major minerals forsterite Mg2SiO4, fayalite Fe2SiO4 and tephroite Mn2SiO4. Olivines are the main constituents of maic and ultramaic rocks that are formed in the earth’s mantle. Olivine-basalt rocks bring the crystals to the surface, where they are found e.g. in extended basalt layers such as in China (Hebei province) (Fig. 2), and the Fig. 3 A Pallasite, an iron-nickel matrix with olivine crystals. Photo © H.A.Hänni USA (Arizona). Another genetic type of olivines is found in rocks formed by metamorphism like in Myanmar or Pakistan. Olivines are also the main constituents of rare pallasites, nickel-iron meteorites, with large inclusions of olivine (Fig. 3). Synthetic forsterites with dopants are used for laser technology applications. Gemstone olivine is called peridot, and also chrysolite. It is represented by a solid mixture between the Mg member forsterite (fo) and the Fe member fayalite (fa), with high fo and low fa concentrations. Occasional Fig. 2 An olivine-basalt rock sample with olivine grain contributions of Mn, Ni or Cr are always very small, but clusters and a larger olivine crystal from Zhangjikou- inluence the colour of the stone. Forsterite and fayalite Xuanhua, Hebei Province, China. are a solid solution series just as pyrope and almandine Photo © H.A.Hänni garnets.
  • Laser Induced Damage in Optical Materials 4Th Kstm Symposium June 14-15, 1912

    Laser Induced Damage in Optical Materials 4Th Kstm Symposium June 14-15, 1912

    175167-^4 OCT 1 7 1975 NATL INST. OF STAND & TECH A UNITED STATI qt\oo DEPARTMENT ( COMMERC ,U57 PUBUCATIOI AlllOb 0 M 00 M 0 NBS SPECIAL PUBLICATION 372 Laser Induced Damage In Optical Materials: 197 U.S. •PARTMENT OF COMMERCE National Bureau irds 00 )S1 •374 NATIONAL BUREAU OF STANDARDS The National 1 Bureau of Standards was established by an act of Congress March 3, 1 901 The Bureau's overall is . goal to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measure- ment system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Center for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scien- tific community, industry, and commerce. The Institute consists of a Center for Radia- tion Research, an Office of Measurement Services and the following divisions: Applied Mathematics—Electricity—Heat—Mechanics—Optical Physics—Linac Radiation 2—Nuclear Radiation 2—Applied Radiation 2—Quantum Electronics 3— Electromagnetics 3—Time and Frequency 3 —Laboratory Astrophysics 3—Cryo- 3 genics .