Osmium

Osmium, chemical element, symbol Os; for physical constants see Periodic Table. Osmium was discovered by Smithson Tennant in 1804. It occurs native associated with platinum and in the mineral iridosmine. The element is obtained commercially as a byproduct of nickel-bearing ores. Osmium, a bluish-white, lustrous, dense, hard and brittle metal, is a member of the platinum group of metals, and has the highest melting point of the group. Osmium forms a volatile oxide that is highly toxic. Powdered osmium metal, like palladium, adsorbs large amounts of hydrogen. The primary use of osmium is to harden other platinum metals. It is used in machine bearings, pen points, and as catalyst. Osmium tetroxide is used as an organic reagent to convert olefins to glycols.