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Platinum group

The platinum group or platinum family is a group of six metal elements with similar physical and chemical properties. The family consists of ruthenium, rhodium, palladium, osmium, iridium, and platinum. These transition metals occupy the rectangular area in the periodic table at the intersection of periodic table groups 7, 8, and 9, with periods 5 and 6.


Naturally occurring platinum and platinum-rich alloys have been known for a long time. Though the metal was used by pre-Columbian Indians, the first European reference to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger (1484-1558) as a description of a mysterious metal found in Central American mines between Darién (Panama) and Mexico ("up until now impossible to melt by any of the Spanish arts").

The Spaniards named the metal platina, or "little silver", when they first encountered it in Colombia. They regarded platinum as an unwanted impurity in the silver they were mining.


The catalytic properties of the six platinum group metals are outstanding. Platinum's wear and tarnish resistance characteristics are well suited for making fine jewelry. Other distinctive properties include resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications.


Platinum, platinum alloys, and iridium are used as crucible materials for the growth of single crystals, especially oxides. The chemical industry uses a significant amount of either platinum or a platinum-rhodium alloy catalyst in the form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for fertilizers, explosives, and nitric acid.

In recent years, a number of platinum-group metals have become important as catalysts in synthetic organic chemistry. Ruthenium dioxide is used as coatings on dimensionally stable titanium anodes used in the production of chlorine and caustic.

Platinum supported catalysts are used in the refining of crude oil, reforming, and other processes used in the production of high-octane gasoline and aromatic compounds for the petrochemical industry. Since 1979, the automotive industry has emerged as the principal consumer of platinum-group metals. Palladium, platinum, and rhodium have been used as oxidation catalyst in catalytic converters to treat automobile exhaust emissions. A wide range of platinum-group metal alloy compositions are used in low-voltage and low-energy contacts, thick- and thin-film circuits, thermocouples and furnace components, and electrodes.

Sources of platinum group metals

An earlier version of this article was adapted from the public domain USGS Minerals Information publication "Platinum-Group Metals Statistics and Information", available online at Please update as necessary.