Discovered in: 1803

Discovered by: Smithson Tennant of England

Description: Named from the Greek word meaning "rainbow" (iridium compounds are quite colorful), iridium is a lustrous silvery-white metal, and is the most corrosion-resistant metal known, being completely unaffected by air, water or acids. It does react with molten salts and bases, and is used as a catalyst. Iridium is very hard and brittle and hardens other metals it is alloyed with, especially platinum. These alloys are used in spark plugs, electrical contacts, and high temperature crucibles.

Biological Rating: No known benefits for life processes in plants or animals.

Biological Benefits: Iridium has no known biological use.

Percentage Amount in the Human Body: Near 0 %

Obtained from: Iridium is found in its pure native form and in osmiridium, a natural alloy of iridium and osmium. Iridium is mined from sulfide layers in mafic igneous rocks where it is present with other platinum-group elements. Most iridium is mined in Canada, Russia and South Africa.