trav·er·tine 
(trăvər-tēn′, -tĭn)
(trăvər-tēn′, -tĭn)n.
1. A light-colored porous calcite, CaCO3, deposited from solution in ground or surface waters and forming, among other deposits, stalactites and stalagmites.
2. A compact calcium carbonate used as a facing material in construction.
[French, from Italian travertino, alteration of tivertino, from Latin (lapis) tīburtīnus, (stone) of Tibur (Tivoli), an ancient city of central Italy.]