dbury, Ontario, Colombia, and the United States also has sources of platinum. The United States uses about 475,000 troy ounces of platinum a year. About 1/5 of this comes from its own mines and scrap. The rest is imported largely from Canada, which recovers large quantities of platinum as a byproduct of the nickel industry. In the United States, platinum is found in the gold deposits in California, Nevada, and Oregon. Large amounts also come from the process of refining gold and copper. The first mine solely for platinum in the United States was built in Stillwater County, Montana in 1988.Platinum is a silver-white metal with a hardness of 4.3. Miners of platinum often refer to it as white gold. It has a high fusing point and is malleable and ductile. Platinum can be hammered as thin as 100 atoms thick. It does not expand very much when heated and has high electrical resistance. Chemically, the metal is relatively inactive and resists attacks by air, water, and single acids. It dissolves slowly in aqua regia, forming chloroplatinic acid. Platinum melts at about 1772 C and boils at about 3827 C. Platinum has oxidation states of +2 and +4. The atomic weight of platinum is 195.09. Platinum has a density of 21.45 g/cm making it one of the densest elements. Platinum is in very few compounds because of its chemical inactivity and is usually alloyed with other metals. Platinum can combine with halogens to form platinum halides. Platinum absorbs large amounts of hydrogen at high temperature. There are six naturally occurring isotopes of platinum: platinum-190, platinum-192, platinum-194, platinum-195, platinum-196, and platinum-198. Platinum-190 is the only radioactive isotope of platinum. Radioactive isotopes of platinum can also be artificially made.Platinum ranks about 72nd in natural abundance among the elements. Except for the mineral sperrylite, which is found rarely in only a few places, platinum occurs in a meta...
