What is "osmiridium"

n. (context mineralogy English) A hard, corrosion-resistant alloy or osmium and iridium used in pen nibs

n. a hard and corrosion resistant mineral that is a natural alloy of osmium and iridium (usually containing small amounts of rhodium and platinum); used in needles and pen nibs etc. [syn: iridosmine]

Osmiridium and iridosmine are natural alloys of the elements osmium and iridium, with traces of other platinum-group metals.

Osmiridium has been defined as containing a higher proportion of iridium, with iridosmine containing more osmium. However, as the content of the natural Os-Ir alloys varies considerably, the constituent percentages of specimens often reflects the reverse situation of osmiridium describing specimens containing a higher proportion of osmium and iridosmine specimens containing more iridium.