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(daɪˈɒpteɪs; -teɪz)
(Minerals) a green glassy mineral consisting of hydrated copper silicate in hexagonal crystalline form. Formula: Cu6Si6O18.6H2O
[C19: from French, from Greek dia- through + optos visible]


(daɪˈɒp teɪs)

a mineral, hydrous copper silicate, CuSiO3∙H2O, occurring in emerald-green crystals.
[< French (1801)]
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References in periodicals archive ?
He showed me a flat of fine Kaokoveld dioptase, but he was also honest enough to tell me that the specimens belong to Stephan Stolte, so we reserved the best five pieces to talk with Stephan about later.
Low blood pressure can be treated here with a light green stone such as chrysoprase and high blood pressure can be treated with a dark coloured specimen such as dioptase.
No really surprising new finds from Namibia showed up this time, but the beauty of dioptase and beryl, while not at all surprising, is always worth a gawk.
The article was discouraging about prospects for actually visiting the mine and buying specimens, but they took a trip to South Africa anyway and were able to buy their first Tsumeb dioptase in Johannesburg.
The same prospect also produces clusters of very bright green dioptase crystals, with individuals to 5 cm.
Dioptase on Calcite Tsumeb, Namibia 2 1/4" wide ex-collections H.
dealership also occupied a room in the Quality Inn, and in that room were just five specimens from a dioptase pocket hit last September at the classic locality of Altyn-Tube, Karaganda Oblast, Kazakhstan.
His ads in November-December began to list the many minerals he obtained, including dioptase from "French Equatorial Africa," tarbuttite crystals on matrix from Northern Rhodesia, and many others.
For example, if you have a table full of dioptase specimens from Tsumeb, Namibia, some of them will automatically appeal to people more than others.
Charlie has also passed on to Rob a few specimens showing gemmy crystals of dioptase from a new find somewhere in the Kaokoveld region of northwestern Namibia.
The locality is well-known for fine examples of common secondary minerals such as cerussite, dioptase and wulfenite, and also for rarer species such as diaboleite, caledonite, bideauxite and leadhillite which represent some of the finest known examples of their species.