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 i...
• (n.) A massive mineral of tin-white or steel-gray color, an arsenide of copper.
a copper arsenide mineral (formulated Cu3As) that is often intergrown with algodonite, another copper arsenide. Both are classified among the ...
Do'mey·kite noun [ Named after Domeyko , a mineralogist of Chili.] (Min.) A massive mineral of tin-white or steel-gray color, an arsenide of copper. 
Copper triarsenide