Like most carbonates, calcite permits solid solution, although it is limited. It occurs in sedimentary rocks in which it can be the predominant mineral. In limestones it is essentially the only mineral. Crystalline, metamorphosed limestones are marbles. Chalk is a fine-grained deposit of calcium carbonate.
Calcite is an important constituent of calcareous marls and calcareous sandstones.
Most limestone has been formed by the deposition of great thicknesses of calcareous material in the form of shells and skeletons of sea animals. A smaller proportion of limestone has formed directly by precipitation of calcium carbonate. An example is Carlsbad Caverns, New Mexico. Both hot and cold calcareous spring water may form cellular deposits of calcite known as travertine or tufa . The deposit at Mammoth Hot Springs, Yellowstone Park was formed in this manner.