Palladium is one of the platinum group metals (PGM), which consist of iridium, osmium, palladium, platinum, rhodium, and ruthenium. These metals are also sometimes referred to as the noble metals due to their resistance to corrosion. This group has all been found to exhibit outstanding catalytic properties which have led to their use in autocatalysts.
Palladium is the least dense and lowest melting of the platinum group metals. Major sources were found in Russia and South Africa. In North America, palladium was found with platinum and other PGMs in Montana where it is now extracted by the Stillwater Mining Compan