Platinum Element,
Alloys and Symbols

• Native Platinum, pt, with some iron and traces of the rare platinum metals. 
• Sperrylite,PtAS2.

Platinum is a rare element which usually occurs native. Its only known compound occurring as a mineral is the arsenide, sperrylite, which has been found very sparingly in two or three localities in association with copper and nickel ores. Platinum is characteristically found associated with the magnesian rocks called peridotites and often with chromite. The only commercial deposits of platinum so far known are placer deposits, the materials of which have been derived from the weathering of the rocks that contained the platinum is disseminated particles. The uses of platinum chiefly depend upon its high fusing point (1700° to 1800° C.) and its resistance to chemical reagents. It is valuable for all sorts of laboratory, such as crucibles, dishes, spoons, etc. It is used in the sulfur acid industry for concentrating kettles and also in the contact process for the manufacture of the acid in the form of finely divided platinum, in contact with which the acid is formed. It is largely used as wire to form the electrical connections with the filaments of incandescent electric lights. It is used in jewelry, particularly as the setting for diamonds in dentistry in the making of  false teeth, in electrical heating apparatus , for sparking plugs in explosion motors, in the measuring of high temperatures, in electrical contacts, etc