Chalcocite
Chalcocite is associated with other copper bearing minerals such as malachite, azurite, bornite and chalcopyrite. Chalcocite is typically steel-gray in colour. The mineral is found in South Africa, Namibia, Zimbabwe and Botswana.
Chemical Formular : Cu2S
Refractive Index : Opaque
Hardness : 2½ – 3 on the Mohs Scale
Crystal System : Monoclinic