 | | Journal (article/letter/editorial) | | THE GEM VARIETIES OF OPAL By RALPH C. GOSSE Albany, New York Introduction This paper is by no means...the many varieties, occurrences, colors, of the opal. Those only of gem quality will be treated here...groups, precious and common. Precious Opal: Any variety of the opal showing a play of color, regardless..."precious" used in connection with opal does not necessarily infer value, an opal may be of the precious variety...not gem quality, and vice versa. Common Opal: Any variety of opal which has no play of color, regardless |  | | Report (issue) | | Aitkens • .' ... INTRODUCTION' * "' • ■' •• The opal, long in disfavor "because it was considered "unlucky...years. For variety and beauty of color the precious opal:*is without a peer. These colors do not come from...DESCRIPTION AND PROPERTIES Unlike mos"t gem stones, the opal is not crystalline. .It is a solidi fied jelly consisting...together with a certain amount of water. In precious opal the water content ranges from 6 to 10 per cent....compounds, as. well-as bitumens, are present. • • Opal is somewhat soft, the hardness ranging from 5-J- |  | | Report (issue) | | Contents 4 Map: Notable Opal Localities 50 BY BRUCE PAUL GABER 6 The Opal Enigma: Science, History...and Pins Afire: Play of Color in Opal BY MAX WEIBEL Sparkling Opal in Ancient Bones: Precious Relics...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 |  | | Journal (issue) | | mmigration Ol ice. Opal Mines, Wbite Cllifs, New South Wales. Oourte8JI Special Opal Nuinber Granite and...1Iuseum. B y 1rilli<1m F. Foshag The Geology of Opal. By, Oilb rrt Hart.. . . . . . . . . . . . . . ...Collettion of Opals. By Tltomwi Jr. Ffuhr, A.JC Opa ls m Virgin Vall<')', X l',·ncla. By flr. 11. C. Dake. . ....Quest of the Opal. B!I If. T. Strnng.. . ....................... . . ('(}Jor Play in Opal. B.11, Il. E... . . . . . . . . . . . . . . . . . . . . . 'fbe Opal. JJy E11,qe11e Jr. B1"11k..................... |  | | Book | | varieties, with favorite location of quartz agate, opal wood — collectors. The petrified gems throughout... tell about other quartz varieties such as the opal, and petrified wood; and to give him the most complete...Other Quartz Chapter 5. Opal and Its 25 30 50 Varieties Glossary of Opal Terms 54 Wood 62 Chapter... ehrysoprase, tigereye, and common and precious opal. In the general opinion of most collectors, chalcedony...processing the surrounding country’s Along the valley of the Roman came upon and unimpressive group | | | Book | | ties and forms of quartz gems other than agate, opal and its varieties, and petrified wood a great favorite...tell abot1t otl1er Cttiartz varieties st1ch as the opal, jasper, ancl petrified wood; a11d to give l1in1...chryso1)rase, tigereye, and common and preciot1s opal. In the gen eral 01)inion of n1ost collectors, chalced...irort1m, the present-clay city of Tre,,es. Along tl1e valley of tl1e ~Ioselle River passecl the Ro111a11 legions...ra11ge ancl l)enetratecl a valley rt1nni11g l)arallel to the Moselle Valley to join r f • • Fie. |  | | Book (volume) | | Company of El Paso, Texas. Information on the Virgin Valley opal deposits was given by G. Keith Hodson of...Stevens Point, Wisconsin, and by A. L. Mahaffey of Nevada, Missouri. The well-known Texas agate localities...account of the agates found in the Mississippi Valley was provided by Irving W. Hurlbut of Muscatine...Kobuk jade locality. Descriptions of San Diego County, California, gemstones and the mines in which they...the generous assistance of many residents of that county. My special thanks are extended to Elbert H. McMacken |  | | Book (edition) | | jasper chalcedony. Same as jasp- agate. agate opal. See opal agate. agate shell. Same as agate snail, a...they spread from a gorge upon a plain, or an open valley bottom. alluvial stone. A mineral that has been...or black variety of Rumanian amber. From Alamash Valley, Moldavia, Rumania. alomite. Trade name for the...color of orangy- as in amber glass and amber opal. amber colophany. Same as amber pitch. amber drop...lac. Same trade green name of chalcedony Valley, California as amber varnish. Amber pitch powdered |  | | Book (edition) | | ruby, emerald, sapphire, pearl, and occasionally opal. The dictionary (Webster's New Collegiate Diction-...that diamond, tuby, sapphire, and emerald are gems. Opal is a gem. So are jade, lapis, garnets and turquoise...are subjective and open to wide interpretation. Opal, a gem, has a hardness of only 5.5 on the Mohs scale...xx), which is really too soft to wear in a ring. Opal is also quite fragile and brittle, and may crack...dehydration. If durability is a major criterion, opal is not a very good gem. Yet it is a gem and has |  | | Book (edition) | | ruby, emerald, sapphire, pearl, and occasionally opal. The dictionary (Webster's New Collegiate Dictionary;...the statement that diamond, and emerald are gems. Opal is a gem, as are jade, lapis, garnets, and turquoise...are subjective and open to wide interpretation. Opal, a gem, has hardness of only 5.5 on Mohs' scale...15), which is really too soft to wear in a ring. Opal is also quite fragile and brittle and may crack...dehydration. If durability is a major criterion, opal is not a very good gem. Yet it is a gem and has | | | Book (edition) | | ruby, emerald, sapphire, pearl, and occasionally opal. The dictionary ( Webster's New Collegiate Dictionary...that diamond, ruby, sapphire, and emerald are gems. Opal is a gem. So are jade, lapis, garnets and turquoise...are subjective and open to wide interpretation. Opal, a gem, has a hardness of only 5.5 on the Mohs scale...xx), which is really too soft to wear in a ring. Opal is also quite fragile and brittle, and may crack...dehydration. If durability is a major criterion, opal is not a very good gem. Yet it is a gen1 and has |  | | Book (edition) | | West African coast. Red, blue akabar. agate opal. See opal agate. agate shell. Same as agate snail, a...they spread from a gorge upon a plain, or an open valley bottom. alluvial stone. A mineral that has been...or black variety of Rumanian amber. From Alamash Valley, Moldavia, Rumania. alomite. Trade nam,e for the...amatrice which is the preferred American spell- opal. amber colophany. Same as amber pitch. amber...H. 6-6 V2 S.G. 2.5 R.I . ; A (2) from Death Valley, California (English). amber lac. Amber ; |  | | Book (edition) | | Corporate Drive, Suite 400, Burlington MA 01803, USA First published 1962 Second edition 1970 Third edition...22 23 24 25 26 27 28 29 30 31 Spodumene Quartz Opal Turquoise Lapis Lazuli Jade – Geology and Mineralogy...Canada, Germany, Thailand, Vietnam, the UK and the USA, making this a truly international collaboration...Gemstones’ becoming ‘Colour and Colour Enhancement’, and ‘Opal’ xiii Preface to the Fifth Edition being extracted...Pierre Gilson including, most importantly, synthetic opal, both white and black, and a corresponding ingenuity |
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