Platinum

Due to its rarity, Platinum is a highly valuable metal. It can be found as native platinum or as a chemically combined alloy, most commonly with other platinum group elements. Platinum lends its name to the platinum-group metal (PGM) family of 6 transition metals (ruthenium, rhodium, palladium, osmium, iridium and platinum) that sit together on the periodic table.  Platinum group metals can occur in nickel and copper deposits as sulfides (Pt,Pd)S), tellurides (PtBiTe), antimonides (PdSb), arsenides (PtAs2) and in an alloy with nickel and copper itself. The Merensky Reef rock formation in South Africa contains 75% of the worlds known platinum.

Where PGMs are found in sufficient concentrations, PGMs are exclusively extracted through an aqua regia leach. Ammonium chloride is then added to the solution to precipitate ammonium hexachloroplatinate which can be converted to platinum metal when heated. Platinum is also produced as a by-product from hydrometallurgical copper and nickel processes. During the electrorefining process, PGMs settle to the bottom as anode mud.