 | | Journal (article/letter/editorial) | | 99, pages 1488–1499, 2014 Australian sedimentary opal-A and its associated minerals: Implications for...precious opal on the world market comes from opal fields in the Great Artesian Basin of Australia pointing...analyzed 20 opal-A samples from the Andamooka (South Australia) and Yowah (Queensland) precious opal fields...silica, the mineral assemblage, and the host rock. Opal-A consists of submicrometer-sized silica spheres...with predominating alunite, kaolinite, illite and gypsum, and omnipresent barite and anatase we conclude |  | | Journal (issue) | | to “ease up”, have face-to-face meetings, go on field trips and organise our Mineral and Fossil Show....Hall for our meetings. We also plan to run some field trips, so keep an eye on this space and our website...almost pure aragonite suspended on a lattice of opal! ( Lab Girl (2016) by Hope Jahren.). ………………………………………………...Photo 1 Black Opal cabochon (30 x40mm) Lady Luck mine, Yowah Opal Field, Queensland, Australia This was a...“Best-in-Show” trophy and he gave me this amazing black opal which has red flashes. Unfortunately I am apprehensive |  | | 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...with opal pattern and color. In this extreme close-up of a Lightning Ridge black opal, the field of view...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 (article/letter/editorial) | | generalization. Keywords: silicification; fossil wood; opal-A; opal-CT; chalcedony; quartz 1. Introduction Citation:...presence of amorphous opal (opal-A), silica with incipient crystallization (opal-C/opal-CT); microcrystalline...eventually fills interstitial spaces, producing solid opal. Depending on the degree of order in the stacked...final product may be either precious opal or common opal. Amorphous opal is characterized by its relatively...contrast, most of the water in crystalline opals (opal-C and opal-CT) is adsorbed H2 O [14,15]. The structural |  | | Book | | the central activity. As part of this evolution, field trips organised by SMLS became increasingly ambitious...Scotland. Later on, SMLS organised many overseas field trips; to Europe, Siberia, Namibia, the USA & Canada...if I don't collect at least something from each field trip. Thus I have accumulated an eclectic collection...tourmalines are distinctive Photo 6. Pseudomalachite. (field of view 1cm across.) Bampfylde mine, Devon. I was...Pseudomalachite -5- David Alderton Photo 7. Scorodite. (field of view 1.7cm across.) Hemerdon mine, Devon. Collected |
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