Description
Dioptase is a copper-silicate mineral with the chemical formula CuSiO2(OH)2 and belongs to the cyclosilicates. This mineral, which ranges from transparent to translucent and has colors ranging from dark blue-green to emerald or turquoise, has a vitreous luster and a green streak. Its cleavage is good along the crystal plane [1011], and it belongs to the trigonal crystal system. With an average density of 3.31, a hardness of 5, and non-radioactive properties, dioptase is a remarkable mineral. It has a birefringence of 0.0510 to 0.0530. Its name is derived from the Greek words "dia" (through) and "optamai" (sight). As a secondary mineral, dioptase occurs in oxidized copper ore deposits, with well-known deposits being Tsumeb and Cochab in Namibia, and Altyn Tube in Kazakhstan. It is also found in the Christmas mine in Gila County, Arizona, USA. Dioptase is highly sought after by mineral collectors but has no other commercial uses. Although beautiful enough to be used as a gemstone, it is not hard or strong enough, so it is rarely cut as such.
