Minerals and microbes have coevolved throughout much of Earth history. They interact at the microscopic scale, but their effects are manifested macroscopically. Minerals support microbial growth by providing essential nutrients, and microbial activity alters mineral solubility and the oxidation state of certain constituent elements. Microbially mediated dissolution, precipitation, and transformation of minerals are either directly controlled by microorganisms or induced by biochemical reactions that usually take place outside the cell. All these reactions alter metal mobility, leading to the release or sequestration of heavy metals and radionuclides. These processes therefore have implications for ore formation and the bioremediation of contaminated sites.