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}, indistinct on {110} and {011}
Fracturesubconchoidal
Specific Gravity2.95
Colorswhite, colorless, gray, yellow, green, blue, violet, brown, pink
Transparencytransparent to translucent
Type LocalityTsumeb, Otjikoto (Oshikoto) Region, Namibia
Mineral GroupCarbonates
Usescollector, jewelry (rarely), industrial (cement, lime, agriculture)
Associated Mineralscalcite, gypsum, malachite, azurite, smithsonite, hemimorphite
Rarityuncommon
Description
This specimen displays a beautiful cluster of radiating, acicular (needle-like) crystals of pale yellow to white aragonite, forming a botryoidal or stalactitic aggregate.
Geological Context
Aragonite is a polymorph of calcite, typically forming at lower temperatures and higher pressures, or in specific aqueous environments such as hot springs, caves (as speleothems), and mollusk shells. It can also occur in metamorphic and sedimentary rocks.
