Rio Tinto is a British-Australian multinational and one of the world's largest metals and mining corporations. The company was founded in 1873, when a multinational consortium of investors purchased a mine complex on the Rio Tinto, in Huelva, Spain, from the Spanish government. Since then, the company has grown through a long series of mergers and acquisitions to place itself among the world leaders in the production of many commodities, including aluminum, iron ore, copper, uranium, coal, and diamonds. The company has operations on six continents, but is mainly concentrated in Australia and Canada, and owns its mining operations through a complex web of wholly and partly owned subsidiaries. Rio Tinto also has significant operations in refining, particularly for refining bauxite and iron ore.