mineral
Calcite
Calcium Carbonate (CaCO3)
Hardness of 3 on the Mohs scale, color typically white or colorless (can be tinted by impurities), vitreous to pearly luster, trigonal crystal system with prominent rhombohedral cleavage, specific gravity of 2.71.
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Physical properties
Hardness of 3 on the Mohs scale, color typically white or colorless (can be tinted by impurities), vitreous to pearly luster, trigonal crystal system with prominent rhombohedral cleavage, specific gravity of 2.71.
Formation & geological history
Forms in sedimentary environments through precipitation of calcium carbonate from water (limestone, marble, and vein deposits), as well as in hydrothermal veins and hot spring deposits.
Uses & applications
Used extensively in construction (as limestone and marble for building materials and cement), agriculture (soil conditioning), chemical industry, and as mineral collector specimens.
Geological facts
Calcite exhibits strong double refraction (birefringence), meaning an image viewed through a transparent crystal appears doubled. It also effervesces (fizzes) when a weak acid like vinegar is applied.
Field identification & locations
Easily identified in the field by its characteristic rhombohedral cleavage, its softness (can be scratched easily with a copper coin), and its reaction with acid. Commonly found worldwide in sedimentary rock formations and cave environments.
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