- a precious metallic element resembling platinum: used in platinum alloys and for the points of gold pens. Symbol: Ir; atomic weight: 192.2; atomic number: 77; specific gravity: 22.4 at 20°C.
- a very hard inert yellowish-white transition element that is the most corrosion-resistant metal known. It occurs in platinum ores and is used as an alloy with platinum. Symbol: Ir; atomic no: 77; atomic wt: 192.22; valency: 3 or 4; relative density: 22.42; melting pt: 2447°C; boiling pt: 4428°C
