iridium

n.

1.

(Chem.) A rare metallic element of atomic number 77, of the same group as platinum, which it much resembles, being silver-white and indifferent to most corrosive agents, but harder, more brittle, and with a higher melting temperature (2410° C, versus platinum 1772° C). With the exception of osmium, it is the heaviest substance known, its specific gravity being 22.4. Symbol Ir. Atomic weight 192.22.

Noun

1.

iridium - a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium Synonyms: atomic number 77, Ir

atomic number 77, Ir, metal, metallic element