This Specimen has been sold.
2.7" Sparkling, Aragonite Crystal Formation - Potosi Mine, Mexico
This is a gorgeous cluster of sparkling aragonite (cave calcite) that was collected from the Potosi Mine in Chihuahua, Mexico. Under short wave UV, this specimen fluoresces vibrant green.
Aragonite is a carbonate mineral with the chemical composition of CaCO3. It is a pseudomorph after calcite and varies in colors depending on impurities. It displays a translucent to white color when pure, and when impure can vary between yellow, green, pink, blue and brown. Typically forming in low temperature hydrothermal veins, It is also known to form in hot springs, as precipitates from chemicals in sedimentary rock, and in some cases as crystals in fossilized sea creatures.
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.