Bioleaching is the extraction or liberation of metals from their ores through the use of living organisms. Bioleaching is one of several applications within biohydrometallurgy and several methods are used to treat ores or concentrates containing copper, zinc, lead,  arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.
Bioleaching falls into two broad categories.  The first, is the use of microorganisms to oxidize refractory minerals to release valuable metals such and gold and silver.  Most commonly the minerals that are the target of oxidization are pyrite and arsenopyrite.
The second category is leaching of sulphide minerals to release the associated metal, for example, leaching of pentlandite to release nickel, or the leaching of chalcocite, covellite or chalcopyrite to release copper.