an important copper sulfide mineral with the formula copper(I) sulfide (Cu2S) containing 80% copper. It acquired its current name in 1868 from the Greek “klalkos”, meaning copper, as an alteration of the now obsolete name chalcosine. It is opaque and dark gray to black with a metallic luster. As a sulfide mineral with high copper content, chalcocite exhibits a relatively high electrical conductivity (~ 1,000 S/m), which is unusual for a mineral.
synonyms: redruthite, vitreous copper, copper-glance
see also: copper sulfide minerals