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A dense, hard metallic element discovered by Smithson Tennant in 1803. Iridium is a rare element that has an abundance of 0.001 ppm in the earth's crust. It is found as a native metal alloyed with Osmium, Platinum, or Gold. Iridium deposits have been found in Canada, South Africa, Russia and the U.S. (Alaska). The white, hard metal is insoluble in acids and does not tarnish in air. Iridium is used to harden platinum. It is also used in jewelry, weight standards, precision instruments, surgical tools, pen points, electrical contacts, and wear-resistant bearings.
Synonyms and Related Terms
Ir; iridio (It., Esp.); Irídio (Port.)
- Flammable solid.
- Spontaneously flammable in air.
- Contact causes irritation.
- Fisher Scientific: MSDS
Physical and Chemical Properties
Resistant to acids. Slowly soluble in fused alkalis.
|Composition||Ir (atomic no. 77)|
|Melting Point||2410 C|
|Molecular Weight||atomic wt = 192.217|
|Boiling Point||4310 C|
Resources and Citations
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 5098; discovered 1804 by Tennant
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- Web Elements at http://www.webelements.com/webelements/elements/text/Ir/hist.html gives discovered in 1803 by Smithson Tennant, Antoine Fourcroy, Louis Vanquelin, Hippolyte Collet-Descotils
- Chemical & Engineering News, American Chemical Society, Washington DC, 81 (36) , Sept. 8, 2003 Comment: Richard Eisenberg, p. 148: discovered in 1803 by Smithson Tennant