3.15" Polished Chocolate Calcite Palm Stone - Pakistan
This is a beautiful, 3.15" wide polished palm stone that was formed from "chocolate calcite", collected from Pakistan. This specimen features alternating bands of white, beige and brown calcite, and has been polished to a glossy finish.
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.