What is Ore-deposit types?

An ore-deposit type is a class of deposits that share a geological setting, a host rock, a form, an ore mineralogy and a forming process, so that a description of the class predicts where its members occur. The types fall into four families by process: magmatic (the metal is concentrated by a magma as it crystallises or unmixes), hydrothermal (by a hot aqueous fluid), sedimentary (by the transport and deposition of sediment, or precipitation from water at the surface), and supergene (by weathering of an earlier deposit).