What is an ore?

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).

Discover more about the processes that form ore deposits (PDF 3.7 MB)

Geological processes

The natural processes that concentrate ore minerals include:

  • fractional crystallization of magmas
  • release of volatiles from a crystallizing magma
  • magmatic interaction with host rocks
  • metamorphic reactions producing fluids
  • chemical changes in circulating heated groundwater
  • organic interactions
  • weathering

The geological features of ore deposits are summarised in a paper by Richard Herrington (2010):

Geological features and mineral deposits PDF (906.9 KB)

Typical Mississippi Valley-type lead-zinc mineralisation from Gloucestershire, UK.
Ores collection

Our collection of more than 15,000 specimens is a valuable resource for the field of economic geology.