The Collaborative International Dictionary of English v.0.48:

Felspar \Fel"spar`\, Felspath \Fel"spath`\, n. (Min.)
   See Feldspar.
   [1913 Webster]

WordNet (r) 3.0 (2006):

felspar
    n 1: any of a group of hard crystalline minerals that consist of
         aluminum silicates of potassium or sodium or calcium or
         barium [syn: feldspar, felspar]