Calcite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameCalcite
Chemical FormulaCaCO3
Mohs Hardness3
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavageperfect rhombohedral on three directions
Fractureconchoidal to uneven
Specific Gravity2.71
Colorswhite, pale yellow, tan
Transparencytranslucent
Type LocalityRivet quarry, Peyrebrune, Réalmont, Tarn, Midi-Pyrénées, France
Mineral GroupCarbonates
Usesconstruction, industrial, optical, collector, jewelry
Associated Mineralssiderite
Raritycommon
Description
This specimen features several large, translucent, off-white to pale tan rhombohedral crystals of calcite, prominently displayed on a matrix of olive-green, bladed siderite crystals.
Geological Context
Calcite is a ubiquitous mineral, forming in diverse environments including sedimentary rocks (limestone, marble), hydrothermal veins, and as a secondary mineral in igneous and metamorphic rocks. It commonly precipitates from calcium-rich waters.
