The Collaborative International Dictionary of English v.0.48:

Chalcopyrite \Chal`co*pyr"ite\, n. [Gr. chalko`s brass + E.
   pyrite. So named from its color.] (Min.)
   Copper pyrites, or yellow copper ore; a common ore of copper,
   containing copper, iron, and sulphur. It occurs massive and
   in tetragonal crystals of a bright brass yellow color.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chalcopyrite
    n 1: a yellow copper ore (CuFeS2) made up of copper and iron
         sulfide [syn: chalcopyrite, copper pyrites]