Tufa

Definition:

() A soft or porous stone formed by depositions from water, usually calcareous; -- called also calcareous tufa.
() A friable volcanic rock or conglomerate, formed of consolidated cinders, or scoria.

Compare tufa with other words:

fiorite vs. tufa

deposit vs. tufa

calcareous vs. tufa

tufa vs. tufaceous

tufa vs. volcanic