Travertine is a sedimentary rock. It is a natural chemical precipitate of carbonate minerals; typically aragonite, but often recrystallized to, or primarily, calcite. Travertine forms as calcium carbonate is deposited from the water of mineral springs or rivulets that are saturated with dissolved calcium bicarbonate. The spring water from which the calcium carbonate precipitates can be hot, warm or cold. The rate of deposition increases with the temperature of the water, or alternatively, when   biotic material   accelerates the process of precipitation. The ornate columns of travertine in caves are an example of an inorganic chemical sedimentary rock.