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iridium

(-ē əm)

noun

a white, extremely dense, brittle, corrosion-resistant chemical element, one of the platinum metals: alloys of iridium are used in electrodes, pen points, crucibles, etc.: symbol, Ir; at. no., 77

Origin: ModL: so named (1804) by S. Tennant (1761-1815), Eng chemist < Gr iris (gen. iridos), iris, because its salts have varied colors; + -ium

See iridium in American Heritage Dictionary 4

noun Symbol Ir

A very hard and brittle, exceptionally corrosion-resistant, whitish-yellow metallic element occurring in platinum ores and used principally to harden platinum and in high-temperature materials, electrical contacts, and wear-resistant bearings. Atomic number 77; atomic weight 192.2; melting point 2,446°C; boiling point 4,428°C; specific gravity 22.562 (at 20°C); valence 2, 3, 4, 6. See Table at element.

Origin:

Origin: From Latin īris, īrid-, rainbow (from the colors produced by dissolving it in hydrochloric acid); see irido-

Origin: + -ium

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