Supergene Processes

In ore deposit geology, supergene processes, also called supergene enrichment, are the changes that occur relatively near the surface, as opposed to the deep hypogene processes. Meteoric water, which is water derived from precipitation, circulates downward, oxidizes the primary sulfide ore minerals and redistributes the metals. Metals leached from the oxidized zone are carried down by percolating groundwater and react with hypogene sulfides at the base of the oxidized zone, forming secondary sulfides richer in metal than the original ore. This is especially noted in copper deposits, where chalcocite and covellite are deposited. The processes take place at close to atmospheric conditions, near room temperature and one atmosphere, and a supergene profile runs from a gossan cap at the surface down to the primary zone.