Aragonite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameAragonite
Chemical FormulaCaCO3
Mohs Hardness3.5
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
CleavageDistinct on {010}, poor on {110} and {011}
Fracturesubconchoidal
Specific Gravity2.95
Colorspurple, gray, white, yellow, green, blue, brown
Transparencytranslucent
Type LocalityGallo river, Molina de Aragón, Guadalajara, Castile-La Mancha, Spain
Mineral GroupCarbonates
Usescollector, industrial
Associated Mineralscalcite, gypsum, zeolites
Raritycommon
Description
This specimen displays prismatic, radiating crystals of aragonite, showing a distinct purple-gray coloration with some lighter, almost white areas and a vitreous luster.
Geological Context
Aragonite is a polymorph of calcite that forms in low-temperature environments such as hot springs, caves (as speleothems), and shells of marine organisms, as well as in some metamorphic rocks and hydrothermal veins.
