'calcareous tufa' definitions:

Definition of 'calcareous tufa'

From: GCIDE

Tufa \Tu"fa\, [It. fufo soft, sandy stone, L. tofus, tophus. Cf. Tofus, Toph, and Tophin.] (Min.) (a) A soft or porous stone formed by depositions from water, usually calcareous; -- called also calcareous tufa. (b) A friable volcanic rock or conglomerate, formed of consolidated cinders, or scoria. [1913 Webster]