An ore is a rock containing a natural concentration of valuable minerals large enough to be worth extracting. Ore deposits are mined and then refined to extract the mineral commodity.
Mineral deposits form as a result of many geological processes, but always within specific geological settings. Minerals with similar characteristics, made by similar processes, may define a class of deposits.
Mineral deposit classes share a set of geological attributes and contain a particular commodity (or commodities) that collectively distinguish them from other types (Eckstrand et al. 1995).
The natural processes that concentrate ore minerals include:
The geological features of ore deposits are summarised in a paper by Richard Herrington (2010):