Copper
Copper occurs in several forms including flat sheets, wire-like fibres and rarely as crystals. Copper can be cleaned with dilute nitric acid, which usually restores the colour and metallic lustre. Copper occurs in the following minerals: Azurite, bornite, chalcocite, chalcopyrite, chrysocolla, covellite, cuprite and malachite. Copper is found in South Africa, Namibia and Zimbabwe.
Chemical Formular : Cu
Refractive Index : Opaque
Hardness : 2½ – 3 on the Mohs Scale
Crystal System : Isometric