Source : Webster's Revised Unabridged Dictionary (1913)

Talc \Talc\, n. [F. talc; cf. Sp. & It. talco, LL. talcus; all
   fr. Ar. talq.] (Min.)
   A soft mineral of a soapy feel and a greenish, whitish, or
   grayish color, usually occurring in foliated masses. It is
   hydrous silicate of magnesia. {Steatite}, or {soapstone}, is
   a compact granular variety.

   {Indurated talc}, an impure, slaty talc, with a nearly
      compact texture, and greater hardness than common talc; --
      called also {talc slate}.