[too-fuh, tyoo-] 
| 1. | Also called calcareous tufa, calc-tufa, calc-tuff. a porous limestone formed from calcium carbonate deposited by springs or the like. Compare travertine. |
| 2. | (not in technical use) tuff2. |
[too-fey-shuhs, tyoo-] , adjective | tu·fa (tōō'fə, tyōō'-) n.
[Obsolete Italian tufa, tufo, from Latin tōfus.] tu·fa'ceous (-fā'shəs) adj. |
| tuff (tŭf) n. A rock composed of compacted volcanic ash varying in size from fine sand to coarse gravel. Also called tufa. [French tuf, from Old French, from Old Italian tufo, tufa; see tufa.] tuff·a'ceous (tŭ-fā'shəs) adj. |
tufa (t 'fə) Pronunciation Key
A soft, friable, and porous sedimentary rock consisting of calcium carbonate and formed by the evaporation of water, especially at the mouth of a hot spring or on a drying lakebed. It is similar to, but harder than, travertine. |