Domeykite is a copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 arsenide mineral

Arsenide mineral

An arsenide mineral is a mineral that contains arsenide as its main anion. Arsenides are grouped with the sulfides in both the Dana and Strunz mineral classification systems.- Examples :* algodonite Cu6As* domeykite Cu3As* löllingite FeAs2* nickeline NiAs...

, 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

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of 7.2 to 8.1.

It was first described in 1845 in the Algodones mines, Coquimbo

Coquimbo

Coquimbo is a port city, commune and capital of the Elqui Province, located on the Pan-American Highway, in the Coquimbo Region of Chile. Coquimbo lies in a valley south of La Serena, with which it forms Greater La Serena with more than 400,000 inhabitants. The commune spans an area around the...

, Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It was named for Lithuanian

Lithuanian

Lithuanian may refer to:* Lithuanian cuisine* Anything related to Lithuania* Anything related to the Grand Duchy of Lithuania* The Lithuanian people* The Lithuanian language...

 mineralogist Ignacy Domeyko

Ignacy Domeyko

Ignacy Domeyko or Domejko was a 19th-century geologist, mineralogist and educator who was born in Nesvizh, Imperial Russia , into a Polish-Lithuanian family...

(1802-89).