Chalcocite
Chalcocite
Sulfide mineral
Chalcocite (/ˈkælkəˌsaɪt/),[6][7] copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system.
The term chalcocite from the Greek khalkos, meaning "copper". It is also known as redruthite, vitreous copper, or copper-glance.[8]