Enargite (Size: about 1.4 mm) Locality: Julcani Mine, Julcani District, Angaraes Province, Huancavelica Department, Peru Original description: Enargite, isolat — Photo: Kelly Nash · CC BY 3.0
Enargite
A steel-gray copper-arsenic sulfosalt — an important copper ore named from the Greek for 'distinct', after its perfect cleavage.
Intro adapted from Wikipedia (CC BY-SA).
Enargite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Cu₃AsS₄.
It crystallizes in the orthorhombic crystal system (space group Pnm2_1). It is a member of the Wurtzite, Enargite structural group.
Key properties: Mohs hardness 3; specific gravity 4.45; typically gray or black; Grayish black streak; Metallic to dull luster.
IMA symbol Eng, grandfathered status — known before the IMA’s founding, named in 1850.
Found in hydrothermal vein deposits formed at medium temperatures. Also as a late-stage mineral in low-temperature deposits.
It is found associated with Pyrite, sphalerite, galena, bornite, tetrahedrite–tennantite, chalcocite, covellite, barite, quartz.
Its name comes from the Greek for distinct, in allusion to its cleavage.
Collections: Metals & Native Elements, Collector Favorites.