Dioptase

Mineral formula: CuSiO₃ · H₂O

Crystal system: Trigonal

Crystal habit: long to short prismatic crystals

Cleavage: Perfect on {1011]

Fracture: irregular to conchoidal

Color: emerald green to blue-green

Luster: sub-adamantine, vitreous, sub-vitreous

Diaphaneity: Transparent to translucent

Moh’s scale hardness: 5

Streak: green

Specific gravity:  3.28 – 3.35

Type locality: Kazakhstan

Geological occurrence: a secondary mineral in the oxidized zone of copper deposits

Named for: the Greek for "through" and "to see" in 1797 by Hauy in allusion to the visibility of internal cleavage planes.