The Collaborative International Dictionary
Iridosmium
Iridosmine \Ir`i*dos"mine\, Iridosmium \Ir`i*dos"mi*um\, n. [Iridium + osmium.] (Min.) The native compound of iridium and osmium. It is found in flattened metallic grains of extreme hardness, and is often used for pointing gold pens.
Wiktionary
iridosmium
n. iridosmine