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| Contents 4 Map: Notable Opal Localities 50 BY BRUCE PAUL GABER 6 The Opal Enigma: Science, History...Afire: Play of Color in Opal BY MAX WEIBEL Sparkling Opal in Ancient Bones: Precious Relics from the Age...vibrant with opal pattern and color. In this extreme close-up of a Lightning Ridge black opal, the field...approximately 3 mm wide. Opal courtesy Jenni Brammall BY ALEX RITCHIE 52 An Opal Glossary of Terms BY...BY SI AND ANN FRAZIER BY PETER HUBER 64 Opal from Mexico: Unsurpassed Fire BY JURGEN SCHUTZ 18 Perfect |
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| diffuse small angle neutron scattering (SANS). Precious opals give rise to two additional intensity maxima...observed. The outer part of the scattering curves of opal-CT and microcrystalline quartz deviates from Porod’s...minerals containing about 1 to 10 wt.% water. Precious (or “noble”) opals consist of a close packing...according to Bragg’s law producing the colours of precious opals (Sanders 1964 and 1968). In potch opals...in opal-CT (Jones and Segnit 1971; Graetsch et al. 1994). The difference between opal-C and opal-CT appears |
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| 1982 Jules Roger Sauer ” Foreword For years Brazil has been the major producer of colored stones in...metamorphic rocks, the variety of gem deposits in Brazil is almost infinite. In addition to the mineral...assemblage one might expect from pegmatite dikes, Brazil also produces a very significant output of diamonds...written in English, and beautifully illustrated. “Brazil, Paradise of Gemstones’, by Jules Roger Sauer,...aquamarines in Rio Grande do Norte, in 1953, the precious opals of Pedro I] in Piaui, in 1960, and a turquoise vein |
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| recently. A good distantvision reading indicated opal, but our customer didn't think it could be, such...nondestructive a n d the material, which was probably opal, was frangible to say the least. A matching density...comparison stone established the stone to be opal. * * * Another opal, which caused me a lot of trouble customerwise...customerwise, not gemmologically, was a black opal purchased as such, mounted in a ring a n d offered for...found the opal colour lipped slightly into the potch and again where potch merged into opal colour. This |
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| Da~c~ Ca 1000.00 10.00 ·' 00.00 (Fe2 OJ /Ti02) <II C . .. 10.00 - ~DO ell 0 o D 100.00 1000...from East Australia and Pailin, PaiIin, using Fe, Ii Ti concentrations, concentrations, however, is is...essentiallyfall fallinto into2 2 show only negligible Ii «0.005% Ti022). ). Ti (<0.005% distinct groups. The...only om from rich 'basaltic' type corundum from and Ii-rich Ti-rich type has 0.1-0.2% Ii0 Ti022.• Many Barrington...2% Fe around 0.07% 0.07% Ti0 Ti02 (Table (TableII).II). around 2 the Anakie and New England fields range |
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| & Row, New York. Ball SH (1950)A Roman Book on Precious Stones. Gemological lnstitute of America, Los...Pavilion None to weak bluish white (sw) ' $7ki ii , -+.-, -'-.A ' * Moderate to strong bluish white...being i n the Rio Grande do Sul mining area of Brazil, close to the Uruguay border, or in northern Uruguay...specimens of sectored amethyst from Minas Gerais, Brazil, which were also obtained from the Gemological...heat-treating sectored amethyst from Minas Gerais, Brazil, in either one of two ways: (1)a medium heating |
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| flux blue, pink and orange sapphires; synthetic opal in a variety of body colours and patterns to their...reading taken on the apex of of the cap with a Duplex II refractometer refractometer revealed a value of of...explanation is that, as with some turquoise and opal, the finished piece may merely have been too thin...(Yule, 1871): "Now I will... tell you of the most precious article that exists in the world. You must know...large rubellite crystals were found in the pegmatite mine at Sakangyi. Furthermore, Bauer (Spencer transi |
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| O’Donoghue Gemstones covers the whole subject of precious stones, incorporating all of the most important...Publication Data O’Donoghue, Michael Gemstones. 1. Precious stones I. Title 553.8 QE392 ISBN 0 412-27390 X...Bibliography: p. Includes index. ISBN 0 412 27390 X 1. Precious stones. I. Title. TS752.03 1987 87-15746 CIP 553...opalescence the milky effect seen in common opal and in some precious opal. Not to be confused with play of colour...itself - olivine may be altered to serpentine and opal or agate may be deposited in cavities. Contact metamorphism |
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| Nontronite Nosean Nsutite Nyerereite Olivenite Olivine Opal Orpiment Otavite Paladium Paragonite Paralstonite...hanging wall. During a subsequent mining period, the mine was re-opened to recover sideritic parts of the...to orange pink hues. All three modifications of precious corundum are rather seldom owing to exceptional...classification of gemstones . Only diamonds are harder than precious corundum minerals. Previous classification schemes...non-metallic raw materials into gemstones s.s. (diamond, precious corundum, topaz and emerald), semiprecious stones |
| | Journal (article/letter/editorial) |
| Nontronite Nosean Nsutite Nyerereite Olivenite Olivine Opal Orpiment Otavite Paladium Paragonite Paralstonite...hanging wall. During a subsequent mining period, the mine was re-opened to recover sideritic parts of the...to orange pink hues. All three modifications of precious corundum are rather seldom owing to exceptional...classification of gemstones . Only diamonds are harder than precious corundum minerals. Previous classification schemes...non-metallic raw materials into gemstones s.s. (diamond, precious corundum, topaz and emerald), semiprecious stones |
