Tufa

·- A friable volcanic rock or conglomerate, formed of consolidated cinders, or scoria.

II. Tufa ·- A soft or porous stone formed by depositions from water, usually calcareous;

— called also calcareous tufa.

tufa
tūfa, ae, f., a kind of helmet-crest; or, acc. to others, a kind of military standard , Veg. Mil....

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
Calc-tufa
·noun ·see under <<Calcite>>. ...

Webster's Dictionary of the English Language