Aragonite
Image: “Jon Zander (Digon3)" (CC BY-SA 3.0)
Mineral NameAragonite
Chemical FormulaCaCO3
Mohs Hardness3.5
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavagedistinct on {010}, imperfect on {110} and {011}
Fractureconchoidal
Specific Gravity2.95
Colorsbrown, orange, tan, white, colorless, gray, yellow, green, blue, violet, pink
Transparencytransparent
Type LocalityMolina de Aragón, Spain (type locality); worldwide in various deposits
Mineral GroupCarbonates
Usescollector, jewelry (minor), industrial (cement, agriculture)
Associated Mineralscalcite, gypsum, celestine, malachite, azurite
Raritycommon
Description
This specimen displays a radiating cluster of prismatic, pseudohexagonal aragonite crystals, exhibiting warm brown and orange-tan hues with a vitreous luster.
Geological Context
Aragonite is a polymorph of calcite, forming at lower temperatures and pressures in sedimentary environments, hot springs, caves (as speleothems), and in the shells of marine organisms. It is metastable and can convert to calcite over geological time.
