limestone

Fossiliferous limestone

Limestone is a sedimentary rock containing at least fifty-percent calcium carbonate. Several different types of limestone exist and are differentiated based on the texture (e.g. oolitic limestone), mineral content (e.g. dolomitic limestone), origin (e.g. coral) and geological age (Carboniferous limestone). Karst topography develops in regions underlain by limestone. Most limestone is partly or wholly are organic in origin and contain the hard parts or shells of mollusks and coral (fossiliferous limestone). Because limestone is mainly calcium carbonate it serves as a store for carbon that is released upon dissolution.