Calcite

Calcite (ˈkal-ˌsīt )- CaCO3

When Calcium carbonate crystallizes it will crystallize in one of three main forms. Aragonite is the Orthorhombic polymorph, and Vaterite is the Hexagonal polymorph, while Calcite is the Trigonal polymorph. Calcite is a member of the Calcite group, which also includes Rhodochrosite and Smithsonite.

Calcite is a very common and widespread mineral with at least 35 varieties and an abundance of forms and colors. Its luster can be vitreous, sub-vitreous, resinous, waxy, or pearly. It has a hardness of 3. It is highly reactive with acids.