Calcite
Species
Common · CaCO₃
The commonest form of calcium carbonate, which also crystallises as aragonite and vaterite, and the main component of limestone and marble. Exhibits perfect rhombohedral cleavage and strong birefringence. Dissolves slowly in acidic water, forming cave systems over geological time.
Identity
- Formula
- CaCO₃
- Chemical class
- Carbonate
- Part of
- Coral, Mother of Pearl, Pearl
- Mineral group
- Rhodochrosite, Siderite, Smithsonite
- Also known as
- Iceland spar (optical variety), Chalk (earthy variety)
Crystallography
- Crystal system
- Trigonal
- Habits
- Rhombohedral, Scalenohedral, Prismatic, Massive, Stalactitic
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 3
- Density
- 2.71 g/cm³
- Luster
- Vitreous, Pearly
- Colors
- colorless, white, yellow, pink, red, blue, green, black
- Streak
- white
- Transparency
- Transparent, Translucent, Opaque
Geology
- Origins
- Sedimentary, Hydrothermal, Metamorphic
- Host rocks
- Marble, Limestone and chalk
- Associated minerals
- Quartz, Fluorite, Dolomite, Pyrite
- Found in
- Chalk, Conglomerate, Dolostone, Lapis Lazuli, Limestone, Marble, Shale, Travertine
- Geography
- worldwide
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- Calcite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Calcite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
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