Platinum History

Platinum is an extremely rare metal, occurring as only 5 ppb in the Earth's crust.

Platinum is often found free in areas of the Americas and alloyed with iridium as platiniridium. The platinum arsenide, sperrylite (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. The rare sulfide mineral cooperite, (Pt,Pd,Ni)S, contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within the Bushveld complex, Transvaal, South Africa. South Africa is the largest producer of platinum in the world.

Platinum, often accompanied by small amounts of other platinum family metals, occurs in alluvial placer deposits in the Witwatersrand of South Africa, Colombia, Ontario, the Ural Mountains, and in certain western American states.

Platinum is produced commercially as a by-product of nickel ore processing in the Sudbury deposit. The huge quantities of nickel ore processed makes up for the fact that platinum is present as only 0.5 ppm in the ore.

Naturally-occurring platinum and platinum-rich alloys have been known for a long time. Though the metal was used by pre-Columbian Native Americans, 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 Darien (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, and often discarded it.

Platinum was discussed by astronomer Antonio de Ulloa and Don Jorge Juan y Santacilia (1713-1773), both appointed by King Philip V to join a geographical expedition in Peru that lasted from 1735 to 1745. Among other things, Ulloa observed the platina del pinto, the unworkable metal found with gold in New Granada (Colombia). British privateers intercepted Ulloa's ship on the return voyage. Though he was well-treated in England, and even made a member of the Royal Society he was prevented from publishing a reference to the unknown metal until 1748. Before that could happen Charles Wood independently isolated the element in 1741.

The definition of a metre for a long time was based on the distance between two marks on a bar of a platinum-iridium alloy housed at the Bureau International des Poids et Mesures in Sèvres, France. A platinum-iridium cylinder serves to this day as the standard of the kilogram and is housed in the same facility as the metre bar. Platinum is also used in the definition of the Standard hydrogen electrode.