Wordnet 3.0
NOUN (1)
1. 
 a radioactive mineral consisting of thorium silicate; 
 it is a source of thorium that is found in coarse granite; 
The Collaborative International Dictionary of English v.0.48:
Thorite \Tho"rite\, n. [So called by Berzelius from the
   Scandinavian god Thor. See Thor.] (Min.)
   A mineral of a brown to black color, or, as in the variety
   orangite, orange-yellow. It is essentially a silicate of
   thorium.
   [1913 Webster]
WordNet (r) 3.0 (2006):
thorite
    n 1: a radioactive mineral consisting of thorium silicate; it is
         a source of thorium that is found in coarse granite