Diopside "eyes-chain" from Brazil.

The mineral Dioptase is a copper-silicate having the chemical formula CuSiO2 (OH) 2. It belongs to the cyclo silicates. The transparent to translucent dark green, emerald green or turquoise Dioptase has a glass sheen, a green stripe color and cleavage of the mineral is good, according to the crystal surface [1011]. The crystal system is trigonal. Dioptase has an average density of 3.31, the hardness is 5 and the mineral is not radioactive. The birefringence of Dioptase is 0.0510 to 0.0530. The name of the mineral Dioptase is derived from the Greek words dia ("through") and optamai, meaning "sight". Dioptase is a secondary mineral which is found in oxidized copper deposits. The type of locations Dioptase and Cochab its Tsumeb in Namibia and Altyn Tube in Kazakhstan. The mineral is also found in the Christmas mine, Gila County, Arizona, United States. Among mineral collectors Dioptase a very sought after mineral. Further, it has no applications. To serve as a gemstone Dioptase is certainly nice enough, but not strong and hard enough. So it is very rare for a gemstone cut.