Source : Webster's Revised Unabridged Dictionary (1913)

Wollastonite \Wol"las*ton*ite\, n. [After Dr. W. H. Wollaston,
   an English chemist, who died in 1828.] (Min.)
   A silicate of lime of a white to gray, red, or yellow color,
   occurring generally in cleavable masses, rarely in tabular
   crystals; tabular spar.

Source : WordNet®

wollastonite
     n : a white or grayish mineral typically found in metamorphic
         limestone; a silicate of calcium