Dioptase
Image: Didier Descouens (CC BY-SA 3.0)
Mineral NameDioptase
Chemical FormulaCuSiO3·H2O
Mohs Hardness5
Crystal Systemtrigonal
Lustervitreous
Streak Colorgreen
Cleavageperfect on {1011}
Fractureconchoidal
Specific Gravity3.3
Colorsemerald-green, dark green, bluish-green
Transparencytransparent
Type LocalityTsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto (Oshikoto) Region, Namibia
Mineral GroupCyclosilicates
Usescollector, minor gemstone
Associated Mineralscalcite, minrecordite, malachite, chrysocolla, azurite, quartz
Rarityuncommon
Description
This specimen features numerous vibrant emerald-green dioptase crystals, exhibiting their characteristic trigonal habit, intergrown with white, blocky calcite crystals and minor yellowish minrecordite.
Geological Context
Dioptase is a secondary copper cyclosilicate mineral that forms in the oxidized zones of copper sulfide deposits, typically in arid climates. It often occurs in association with other secondary copper minerals.
