Dioptase is a mineral of Copper Cyclosillicate, varying between translucent to transparent shades of dar bluish green to emerald green. With a sub-adamantine to vitreous sheen, and a hardness of 5, it resembles the tooth enamel. It has a specific gravity reading 3.28 to 3.35 and one class and two perfect cleavage directions.
Dioptase is highly brittle; you must take care to handle its specimens with utmost care. Dioptase is a mineral with a trigonal configuration, with crystals that are six-sided, and terminating in a rhombohedra.
CuSiO3·H2O (also reported as CuSiO2(OH)2
Derivation of Name
The eminent French mineralogist who discovered the mysterious Altyn-Tyube mineral named it dioptase in 1979. The name dioptase is derived from Greek, “dia" meaning “through" and “optima" meaning vision, referring to the two cleavage directions which are visible within complete crystals.
Dioptase is a rare mineral, mostly found in desert areas wherein it gets created as a secondary mineral in deposits of copper sulfides located in oxidized zones. It has a complex process of formation as copper sulfide needs to be adequately oxidized to form crystals of dioptase since silica generally dissolves in water only very minutely unless it has high alkaline pH. Sulfides on getting oxidized, produce extremely acidic liquids with high content of sulfuric acid, which would restrain solubility of silica. Nevertheless, with sufficient time and in dry climatic conditions, particularly in those regions of mineral deposits wherein acids are protected by carbonates, small amounts of silica could react with dissolved copper resulting in the formation of chrysocolla and dioptase.
Collectors of minerals do a great deal in collecting Dioptase which are infrequently cut in the shape of tiny gems like emerald. The comparatively well-known copper silicate minerals are the chrysocolla and Dioptase. This delicate gem will shatter into pieces if it is exposed to ultrasonic cleaning, hence be cautious. Dioptase is used in painting as a ground pigment.
In Kazakhstan the Altyn Tube Mine continues to produce very good samples of dioptase. This host mineral, a quartzite, brownish in color, identifies itself from the specimens of other regions. It is in the Tsumeb Mine in Tsumeb, Namibia that the purest samples of every variety.
The Green mineral Dioptase is very attractive and among the few minerals that can defy the peerlessness of emerald's deep green. Unfortunately, it is too soft to be a gemstone and has good cleavage and therefore, is not generally cut as a gemstone. The specimens of mineral that dioptase creates, are indeed a treasure for anyone who is fond of deep green colors.
Mohs Scale Hardness