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.
Palladium itself is atomic number 46 of the Periodic Table, with chemical symbol Pd. It occurs on earth with a relative abundance of 0.0006 parts per million. Besides being a white and malleable metal, at room temperatures it has the unusual property of absorbing up to 900 times its own volume of hydrogen. Hydrogen readily diffuses through heated palladium and this provides a means of purifying the gas.
The history of Palladium is tied with the history of the platinum group metals because they usually are found together in some combination and because their history is one of determining how to separate them. Find out more about palladium history. Once commerce and demand arose for these metals, then finding commercially viable sources and production became necessary to satisfy that demand. 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 Company. Find out more about the history of Stillwater Mining Company.