Calcite is used in several things such as toothpaste, chewing gum, soap, glue, antacids etc. Calcite has also been used since time immemorial to make mortar. In this use it is employed to make asphalt and cement mixes. Marble for instance has been widely used for interiors and carvings. Travertine is also widely used in interiors. A transparent form is Iceland Spar has been used for crystallography and optical research. Mexican onyx is a variety that is used for purposes of ornamentation. Calcite is a stable form of Calcium Carbonate (CaCO3) which is widely distributed over the earth in abundant quantities. It is also found in the shells of oysters and clams. Calcite is known to be affected by chemical weathering. Stalagmites and Stalactites are formed by precipitated calcite.