Tufa
- A friable volcanic rock or conglomerate, formed of consolidated cinders, or scoria.
- A soft or porous stone formed by depositions from water, usually calcareous; — called also calcareous tufa.
The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.