5 Photos
Domeykite
Chemical Formula	Cu3As
Species	Arsenic
Crystal System	Isometric
Mohs Scale	3
Specific Gravity	7.2-8.1
Color	Tin-white to steel-gray
Streak	Black gray
Luster	Metallic
Diaphaneity	Opaque
Cleavage	None
Fracture	Irregular/Uneven
Crystal Habit：Reniform, botryoidal; massive
Geological Setting：Hydrothermal veins

Domeykite is a copper arsenide mineral, Cu₃As. It crystallizes in the isometric system, although crystals are very rare. It typically forms as irregular masses or botryoidal forms. It is an opaque, white to gray (weathers brassy) metallic mineral with a Mohs hardness of 3 to 3.5 and a specific gravity of 7.2 to 8.1.

It was first described in 1845 in the Algodones mines, Coquimbo, Chile. It was named for Lithuanian mineralogist Ignacy Domeyko (1802-89).