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)
Argentine Pass iron pyrite, cupriferous pyrite (chalcopyrite), and some tetrahedrite. This was the first major discovery of silver ore in Colorado. They named the deposit the Belmont Lode (from the French for "beautiful mountain"), and the surrounding area came to be known as the Argentine mining district (from "argentum", Latin for silver). The discovery led to the growth of Georgetown as an early center of the silver mining industry in Colorado, although development was slowed by a general ignorance of how to properly treat the ore, by the high cost of transportation from the mines, and by the climate at that altitude.