Platinum May 29 2014
Platinums' resistance to wear and tarnish is well suited to use in fine jewelry.
Platinum is an extremely rare metal, occurring at a concentration of only 0.005 ppm in the Earth's crust. It is sometimes mistaken for silver (Ag). Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum group metals and iron mostly. Most often the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum group metals.
Another large alluvial deposit is in the Ural Mountains, Russia, and it is still mined. In nickel and copper deposits,platinum group metals occur as sulfides (e.g. (Pt,Pd)S), tellurides (e.g. PtBiTe), antimonides (PdSb), and arsenides (e.g. PtAs2), and as end alloys with nickel or copper. Platinum arsenide, sperrylite (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, Alaska, about 17,000 kg (550,000 ozt) had been mined between 1927 and 1975. The mine ceased operations in 1990. 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, Gauteng, South Africa. In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906. The largest known primary reserves are in the Bushveld complex in South Africa.
The large copper–nickel deposits near Norilsk in Russia, and the Sudbury Basin, Canada, are the two other large deposits. In the Sudbury Basin, the huge quantities of nickel ore processed make up for the fact platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States, for example in the Absaroka Range in Montana. In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was 192,000 kg. Platinum deposits are present in the state of Tamil Nadu, India. and a MOU has been signed between Geological Survey of India with TAMIN – Tamil Nadu Minerals Ltd. Platinum exists in higher abundances on the Moon and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of bolide impact on the Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.