Dioptase

Real mineral · rare · CuSiO₂(OH)₂

Copper silicate hydroxide forming vivid emerald-green crystals in the oxidised zones of copper deposits. Despite its intense colour, its softness and perfect cleavage make it fragile as a gemstone. Valued as a collector mineral.

Identity

Formula

CuSiO₂(OH)₂

Chemical class

silicate

Also known as

Emerald copper (archaic)

Crystallography

Crystal system

trigonal

Habits

prismatic, rhombohedral

Fracture

conchoidal

Physical properties

Mohs hardness

5

Density

3.28 g/cm³

Luster

vitreous

Colors

dark green, blue-green, green

Streak

pale green

Transparency

transparent, translucent

Geology

Origins

sedimentary, hydrothermal

Host rocks

copper deposits (oxidized zones)

Associated minerals

Malachite, Chrysocolla, Calcite, Wulfenite

Geography

Namibia, Kazakhstan, DR Congo, USA, Chile

Classification

Rarity

rare

Gem quality

Yes

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