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}.