Iron oxide copper gold ore deposits to be within Neoproterozoic to Mesoproterozoic basement. Worldwide, ages of recognised IOCG deposits range from 1.8 Ga to 15 Ma, however, the majority are within the 1.6 Ga to 850 Ma range. Ore minerals in IOCG deposits are typically copper-iron sulfide chalcopyrite and gangue pyrite, forming 10–15% of the rock mass. Supergene profiles can be developed above weathered examples of IOCG deposits, as exemplified by the Sossego deposit, Para State, Brazil, where typical oxidised copper minerals are present, e.g.; malachite, cuprite, native copper and minor amounts of digenite and chalcocite. Alteration is a mixture of sodic-calcic (albite-epidote) to potassic (K-feldspar)
Broken Hill ore deposit mining is concentrated in the Blackwood Open Cut, which commenced in 1973, and the Kintore Open Cut. Stope fill, plus remnant supergene silver and sulphide ore characterize the ore reserve. Pasminco Limited took over the leases of The Zinc Corporation, Limited, and New Broken Hill Consolidated Limited. Their main shafts included ZC, NBHC and Southern Cross. These ZC Mines Leases lie south of the MMM Mining Leases along the Broken Hill "line of lode". By the early 1950s the Broken Hill area had suffered a major drought of over 8 years which was close to shutting down the mining operation.