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.