Chemistry of Osmium

Discovered in 1803 by Smithson Tennant (most famous for his determination that diamond is just a form of carbon), osmium is a very dense, blue-white hard metal. Its name is taken from the Greek, osme, for "odor". The oxides of osmium emit highly toxic gases and form readily when the metal is exposed to air. Thus there are few commercial applications for osmium except as a minor alloying agent where it reduces frictional wear ("osmiroid" ball point pen tips, for example). Most osmium is recovered as a by-product of the refining of platinum and nickel ores. Osmium tetroxide, OsO4, is very poisonous, has a pungent smell and can cause blindness; it is a powerful oxidizing agent, and is used to stain biological materials