This Specimen has been sold.
2.9" Manganoan Calcite Crystal Cluster - Highly Fluorescent!
This is a cluster of pink manganoan (manganese-bearing) calcite crystals from the Pachapaqui mining district in Áncash, Peru. Under short and long wave UV, the calcite crystals fluoresce a vibrant pink-orange color.
Manganoan calcite, also known as manganocalcite is a pink, manganese rich variety of calcite with a chemical composition of (Ca,Mn)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. Often this variety of calcite will exhibit fluorescent properties.
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.