Aragonite
Image: JJ Harrison (https://www.jjharrison.com.au/) (CC BY-SA 4.0)
Mineral NameAragonite
Chemical FormulaCaCO3
Mohs Hardness3.5
Crystal Systemorthorhombic
Streak Colorwhite
CleavageDistinct on {010}, poor on {110} and {011}
Fracturesubconchoidal to uneven
Specific Gravity2.95
Colorsreddish-brown, orange-brown, white
Transparencytranslucent
Type LocalityLos Molinillos, Cuenca, Spain
Mineral GroupCarbonates
Usescollector's specimens, industrial raw material
Associated Mineralscalcite, gypsum, sulfur, zeolites
Raritycommon
Description
This specimen is a pseudohexagonal aggregate of reddish-brown to orange-brown translucent aragonite crystals, exhibiting distinct prismatic forms. The crystal faces show some striations and a vitreous to resinous luster.
Geological Context
Aragonite forms in various low-temperature environments, including hot springs, caves (as speleothems), and sedimentary rocks, as well as in some metamorphic and igneous settings. It is a metastable polymorph of calcite.
