Osmium was discovered in 1803. It occurs in iridosule, platinum-bearing river sands, and nickel-bearing ores.

The metal is bluish white and lustrous, and hard and brittle even at high temperatures. It's difficult to fabricate and produces osmium tetroxide, a highly toxic and powerful oxidizing agent with a strong smell. Even very low concentrations have caused lung, skin, and eye damage.

Osmium tetroxide has been used in fingerprint detection and tissue staining. But most often, the metal is used in alloys with other platinum group elements to make fountain pen tips, instrument pivots, phonograph needles, and electrical contacts.