the weathering of rocks is a natural phenomenon which leads to the enrichment of various metal ores. The process was found to be mediated by bacteria, as research conducted in northern Chile revealed. According to the findings of the study, bacteria could be mediators in copper sulphide enrichment during the process of weathering.

Many of the world's major copper deposits were formed by supergene (high-grade ore) enrichment during weathering. Supergene chalcocite (Cu2s) enrichment during weathering is a very important process from the economic angle as it could lead to a several-fold increase in the copper content of sulphide deposits. The progressive replacement of hypogene (low-grade ore) sulphides, especially chalcopyrite (CuFes2) and pyrite by copper-rich sulphides of the chalcocite (Cu2s) group