3.7" Cobaltoan Calcite Crystal Cluster - Bou Azzer, Morocco
This is a cluster of pink cobaltoan calcite crystals from the Agoudal Mine in Morocco.
Cobaltoan calcite, also known as cobaltocalcite, is one of many different varieties of calcite, forming with a chemical composition of (Ca,Co)CO3. It crystallizes in a trigonal crystal system and forms rhombohedral or scalenohedral crystals. These crystals tend to display a pink color of which intensity can range anywhere from a pinkish-salmon to a hot pink.
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.