The Collaborative International Dictionary of English v.0.48:

Copper \Cop"per\, n. [OE. coper (cf. D. koper, Sw. koppar, Dan.
   kobber, G. kupfer), LL. cuper, fr. L. cuprum for earlier
   Cyprium, Cyprium aes, i.e., Cyprian brass, fr. Gr. ? of
   Cyprus (Gr. ?), anciently renowned for its copper mines. Cf.
   Cypreous.]
   1. A common metal of a reddish color, both ductile and
      malleable, and very tenacious. It is one of the best
      conductors of heat and electricity. Symbol Cu. Atomic
      weight 63.3. It is one of the most useful metals in
      itself, and also in its alloys, brass and bronze.
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   Note: Copper is the only metal which occurs native abundantly
         in large masses; it is found also in various ores, of
         which the most important are chalcopyrite, chalcocite,
         cuprite, and malachite. Copper mixed with tin forms
         bell metal; with a smaller proportion, bronze; and with
         zinc, it forms brass, pinchbeck, and other alloys.
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   2. A coin made of copper; a penny, cent, or other minor coin
      of copper. [Colloq.]
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            My friends filled my pockets with coppers.
                                                  --Franklin.
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   3. A vessel, especially a large boiler, made of copper.
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   4. pl. Specifically (Naut.), the boilers in the galley for
      cooking; as, a ship's coppers.
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   Note: Copper is often used adjectively, commonly in the sense
         of made or consisting of copper, or resembling copper;
         as, a copper boiler, tube, etc.
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               All in a hot and copper sky.       --Coleridge.
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   Note: It is sometimes written in combination; as,
         copperplate, coppersmith, copper-colored.
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   Copper finch. (Zool.) See Chaffinch.

   Copper glance, or Vitreous copper. (Min.) See
      Chalcocite.

   Indigo copper. (Min.) See Covelline.
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The Collaborative International Dictionary of English v.0.48:

Chalcocite \Chal"co*cite\, n. [Gr. chalko`s brass.] (Min.)
   Native copper sulphide, called also copper glance, and
   vitreous copper; a mineral of a black color and metallic
   luster. [Formerly written chalcosine.]
   [1913 Webster] Chalcographer

WordNet (r) 3.0 (2006):

copper glance
    n 1: a heavy grey mineral that is an ore of copper [syn:
         chalcocite, copper glance]