Source : Webster's Revised Unabridged Dictionary (1913)

Leucopyrite \Leu*cop"y*rite\ (l[-u]*k[o^]p"[i^]*r[imac]t), n.
   [Leuco- + pyrites.] (Min.)
   A mineral of a color between white and steel-gray, with a
   metallic luster, and consisting chiefly of arsenic and iron.