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(Minerals) mineralogy a brittle green gem
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈyu kleɪs, -kleɪz)

a rare green or blue mineral, beryllium aluminum silicate, BeAlSiO4(OH), occurring in prismatic crystals: used as a gem.
[1795–1805; < French; see eu-, -clase]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Krambrock, "Radiation-induced defects in euclase: formation of O- hole and [Ti.sup.3+] electron centers," Physics and Chemistry of Minerals, vol.
Especially since World War II, the pegmatites of the state of Minas Gerais have yielded some of the world's finest specimens of topaz, chrysoberyl, euclase, elbaite, and beryl (in all of its colored varieties); phosphate-rich pegmatites of the same state have furnished the world's finest specimens of brazilianite, beryllonite, eosphorite, hydroxylherderite, amblygonite and more; complex pegmatites of other kinds have provided cassiterite, xenotime, monazite and several rare-earth species; Brazilian specimens of titanite, phenakite, fluorapatite, kyanite, scheelite, spessartine and bertrandite are among the world's very best.
Gemmy blue euclase crystals from the emerald mines of Colombia also are not "new," but who can resist taking note of any hoard, however small, of these gorgeous objects?
(1963) On the paragenesis of accessory beryl, phenakite and euclase in topaz-morion pegmatites.
Desautels, in fact, was still the Curator when the taxpayers in question donated a variety of specimens to the Smithsonian, among them, a sinhalite, a cat's-eye rubellite tourmaline, a couple of euclase crystals, several cerussite specimens, some wulfenite specimens and a few anglesite crystals.
Saying that large and fine euclase specimens are rare is an understatement.
Berthold Ottens ( had some specimens from the exciting Chinese find of euclase of which Tucson showgoers became aware in 2007.
Concerning the final Chinese item, namely very fine euclase, available knowledge is much skimpier--and (to impart a positive spin, here) future prospects thus seem even more exciting.
Many cases at the Main Show tackled South American Minerals, the hands-down best of them being the Smithsonian's case, with 21 amazing pieces including a totally gemmy blue 5-cm euclase crystal from Ouro Preto, Minas Gerais, Brazil; a single, thick, lustrous, still-red proustite crystal 9.5 cm long from Chanarcillo, Chile (a gift from J.
One more important fact was that the Heleno Cipriano mine near Itacambira had produced a few flat euclase crystals with spearpoint terminations, the crystals reaching 6 X 10 cm, a few being doubly terminated.
There were 12 bicolored red/green scepter tourmaline crystals of highest quality; brazilianite matrix specimens 30 cm wide; superbly crystallized rose quartz clusters with childrenite rosettes; doubly terminated herderite crystals more than 10 cm long, on matrix; morganite crystals with phantoms; euclase crystals to 6 cm, the smaller ones richly colored.