2.9" Dogtooth Crystal Cluster - Pakistan
This is a calcite crystal cluster that was collected from the Loralai District of Balochistan, Pakistan. In the cleaning process some of the crystals were slightly altered by the acid, which inadvertently left behind a very interesting specimen.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.