The Collaborative International Dictionary of English v.0.48:

Chrysoberyl \Chrys"o*ber`yl\, n. [L. chrysoberyllus, Gr. ?;
   chryso`s gold + ? beryl.] (Min.)
   A mineral, found in crystals, of a yellow to green or brown
   color, and consisting of aluminia and glucina. It is very
   hard, and is often used as a gem.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chrysoberyl
    n 1: a rare hard yellow green mineral consisting of beryllium
         aluminate in crystal form; used as a gemstone