Category:Tufa

Tu"fa, etym: [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.