Osmium

Osmium (from Greek ὀσμή osme, "smell") is a chemical element Os and atomic number 76. It is a hard, brittle, bluish-white transition metal that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with an experimentally measured (using x-ray crystallography) density with platinum, iridium , and other platinum-group metals to make fountain pen , electrical contacts, and in other applications that require extreme durability and hardness The element's abundance in the Earth's crust is among the rarest.