chalcosine

from 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
    

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