travertine

   1. Hard calcareous mineral deposited by flowing water, that is the same as the calcareous variety of sinter and comparable to the softer tufa. The term is normally used only for deposits formed outside caves, where plants and algae cause the precipitation by extracting carbon dioxide from the water and give travertine its porous structure. Travertine forms most commonly on waterfalls that build up like gour dams. Famous examples include those at Plitvice in Croatia, Dunn’s River Falls in Jamaica, and, largest of all, Band-I-Amir in Afghanistan [9].

   2. Calcium carbonate, CaCO3, light in color and generally concretionary and compact, deposited from solution in ground and surface waters. Extremely porous or cellular varieties are known as calcareous tufa, calcareous sinter, or spring deposit. Compact banded varieties, capable of taking a polish, are called onyx marble or cave onyx [10].

   3. Generally compact calcium carbonate rock formed by precipitation of soluble bicarbonates when equilibrium is lost due to changes in temperature and chemical characteristics. Soft, porous variety is called calcareous tufa [20].

   Synonyms: (French.) travertin; (German.) Kalktuff, Sinter, Travertin; (Greek.) travertinis/ asvestolithikos toffos; (Italian.) travertino; (Russian.) travertin; (Spanish.) travertino, toba; (Turkish.) traverten, sutaÕ2; (Yugoslavian.) sedra, travertin, bigar, lehnjak.

   Related to sinter and tufa.