Dioptase
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Description
An emerald-green copper silicate mineral that has been used as a gemstone since Greco-Roman times. The prismatic dioptase crystals are found in large clumps which tend to fracture unevenly. Dioptase is found usually near copper deposits and occurs in Russia, Congo, Central African Republic, South-West Africa, Zaire, Chile, and the United States (Arizona).
Synonyms and Related Terms
dioptasa (Esp.); dioptase (Fr., Port.); Dioptas (Deut.); dioptaas (Ned.)
Physical and Chemical Properties
- Color = dark teal to emerald green
- Hexagonal crystal system with prismatic crystals.
- Cleavage is perfect in three directions.
- Fracture = conchoidal and brittle
- Luster = vitreous.
- Streak = pale greenish-blue.
- Composition = CuSiO2(OH)2
- Mohs Hardness = 5.0
- Density = 3.28-3.35 g/ml
- Refractive Index = 1.65-1.71
Resources and Citations
- Mineralogy Database: Dioptase
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia: http://en.wikipedia.org/wiki/Dioptase (Accessed Sept. 7, 2005 and Feb 2026)
- IAP: Green Pigments