The Collaborative International Dictionary of English v.0.48:

Barytes \Ba*ry"tes\, n. [Gr. bary`s heavy: cf. Gr. bary`ths
   heaviness, F. baryte.] (Min.)
   Barium sulphate, generally called heavy spar or barite.
   See Barite.
   [1913 Webster]

WordNet (r) 3.0 (2006):

barytes
    n 1: a white or colorless mineral (BaSO4); the main source of
         barium [syn: heavy spar, barite, barytes, barium
         sulphate]