pyrophyllite

from WordNet (r) 3.0 (2006)

pyrophyllite
    n 1: a white or greenish aluminum silicate mineral (resembles
         talc)

from The Collaborative International Dictionary of English v.0.48

Pyrophyllite \Py*roph"yl*lite\, n. [Pyro- + Gr. ? leaf.] (Min.)
   A mineral, usually of a white or greenish color and pearly
   luster, consisting chiefly of the hydrous silicate of
   alumina.
   [1913 Webster]