Platinum

Platinum

Platinum, symbol Pt, is a relatively rare, metallic element that is more expensive than gold. The atomic number of platinum is 78. Platinum is one of the transition elements in group 10 of the periodic table. Platinum is the most important of the group of elements called platinum metals. Also included in this group are the metals ruthenium, rhodium, palladium, osmium, and iridium. Platinum metals were probably used in alloyed forms in ancient Greece and Rome and were first mentioned in European literature in the early 16th century. The separation of the other platinum metals from platinum and from each other was accomplished in the early 19th century.

An Italian scientist named Julius Scaliger discovered platinum in 1557, but fairly large quantities were not discovered until around 1750, when the Spaniards discovered it in Peru. Don Antonio de Ulloa wrote the first complete description for the Spaniards and is sometimes credited with the discovery because of the detailed report. The Spaniards named the metal platinum, deriving form their word plata, meaning silver. The ore, called native platinum, usually occurs in beds of gold-bearing sand. Native platinum contains from 60 to 85 % pure platinum. The small, irregular grains that contain the ore also contain other rare metals, such as iridium, osmium, palladium, rhodium, and ruthenium. The grains also contain small amounts of iron, copper, chromium, and titanium. The grains must be introduced to aqua regia, which dissolves the platinum and can then be collected. Platinum is a rare element on Earth. Platinum makes up an estimated 0.01 parts per million in the Earth's crust. A large nugget of platinum will be found very rarely. The largest nugget ever found was a lump weighing over 21 pounds in Russia. Russia produces the world's largest supply of platinum-group metals. Other major sources of platinum are located in the Transvaal province in South Africa, Sudbury, 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.