The Collaborative International Dictionary of English v.0.48:

Glaucodot \Glau"co*dot\, n. [Gr. glayko`s silvery, gray +
   dido`nai to give.] (Min.)
   A metallic mineral having a grayish tin-white color, and
   containing cobalt and iron, with sulphur and arsenic.
   [1913 Webster]