Rhodium [Rh, 45]

Rhodium (Rh) is a silvery-white, hard metal of group 9 in the periodic table of elements, is the least frequent element of the platinum group metals (PGMs), and is chemically inert. It reveals both siderophilic and chalcophilic properties. Its average content in the Earth’s crust is estimated to be 0.06 µg/kg, and its contents in rocks vary within the range of 0.01–20 µg/kg. It may be accumulated in coal, up to about 100 µg/kg. It tends to occur along with deposits of PGMs and is primarily obtained as a by-product of mining and refining Pt. It is also mined from the Cu–Ni deposits, mainly in Monchegorsk area, the Kola Peninsula (Russia). The main minerals of these ores are pyrrhotite, magnetite, pentlandite, chalcopyrite, Ti magnetite, and pyrite, in which Rh contents vary from 4 to 2780 µg/kg (Gregurek et al. 1999).