The copper deposits at Girilambone, New South Wales

A large open cut on the site of the old Girilambone mine workings and three small satellite deposits have been mined for a heap leach operation using oxidised and supergene enriched ores. Weathering of primary mineralisation, comprising pyrite and chalcopyrite associated with quartzite, chlorite and sericite schists, has given rise to well-developed oxidised and supergene-enriched zones. The oxidised zone is characterised by extensive development of the secondary copper phosphate minerals libethenite and pseudomalachite. Lower in the profile, malachite, azurite, and cuprite dominates the secondary copper mineralisation. At depth, this zone gives way to one containing considerable masses of native copper coated with cuprite and passes into a supergene-enriched blanket of chalcocite. Spectacular specimens of these minerals were recovered as mining proceeded and represent some of the finest examples of secondary copper minerals discovered in Australia.