IRIDIUM (IR)

last update 01 oct 08

* Iridium is a member of the transition metals family:

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   IRIDIUM / Ir / 77

   A lustrous, silvery, hard, dense, brittle metal, a member of the
   "platinum" group of metals.  It is extremely resistant to
   corrosion.  There are two isotopes that occur in nature, both
   stable:  Ir<193/77> (63%) and Ir<191/77> (37%).

     atomic weight:       192.217
     abundance:           84th
     density:             22.42 g/cc
     melting point:       2,410 C
     boiling point:       4,130 C
     valence:             3 <4>
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A few tonnes of iridium are produced every year, usually as a byproduct of platinum production. Iridium is the least corrosive element, and it used to plate the tips of spark plugs, in alloys (particularly with osmium), and as a catalyst.