Dioptase (CuSiO₃·H₂O) is a vivid emerald-green copper silicate that ranks among the most visually striking minerals on Earth. Its color rivals gem emerald, and it forms sharp prismatic to rhombohedral crystals in the oxidized cap of copper deposits. Tsumeb (Namibia) and Mindouli/Mfouati (Republic of Congo) produce world-class specimens.
Key Facts
- Mohs hardness 5 — moderately soft for a gem-class species.
- Vibrant emerald-green color; transparent to translucent.
- Forms in arid oxidized zones of copper sulfide deposits.
- Cleaves perfectly along rhombohedron, making it fragile and difficult to facet.
- Often associated with calcite, malachite, plancheite, and shattuckite.
Notable Localities
Tsumeb (Namibia) and Mindouli (Republic of Congo) are the world’s premier sources. Altyn Tyube (Kazakhstan) is the historical type locality. Christmas Mine (Arizona) produces fine US specimens.
Found at these Localities
- Tsumeb Mine (楚梅布矿)
