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.
Tu*fa"ceous (?), a. [Cf. It. tufaceo, L. tofaceus, tofacius. See Tufa.]
(Min.) Pertaining to tufa; consisting of, or resembling, tufa.
Tuff (?), n. (Min.) Same as Tufa.