资料来源 : pyDict

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资料来源 : Webster's Revised Unabridged Dictionary (1913)

Iridium \I*rid"i*um\, n. [NL., fr. L. iris, iridis, the rainbow.
   So called from the iridescence of some of its solutions. See
   {Iris}.] (Chem.)
   A rare metallic element, of the same group as platinum, which
   it much resembles, being silver-white, but harder, and
   brittle, and indifferent to most corrosive agents. With the
   exception of osmium, it is the heaviest substance known, its
   specific gravity being 22.4. Symbol Ir. Atomic weight 192.5.

   Note: Iridium usually occurs as a native alloy with osmium
         (iridosmine or osmiridium), which may occur alone or
         with platinum. Iridium, as an alloy with platinum, is
         used in bushing the vents of heavy ordnance. It is also
         used for the points of gold pens, and in a finely
         powdered condition (iridium black), for painting
         porcelain black.

资料来源 : WordNet®

iridium
     n : a heavy brittle metallic element of the platinum group; used
         in alloys; occurs in natural alloys with platinum or
         osmium [syn: {Ir}, {atomic number 77}]