The primary component of limestone and marble, calcite is one of the most widespread minerals. It reacts vigorously with dilute hydrochloric acid, making it easy to identify in the field. Color: Colorless, white, yellow, blue, green. Luster: Vitreous to pearly. Streak: White. Cleavage: Perfect rhombohedral 3 directions. Hardness: 3. Transparency: Transparent to translucent. Crystal system: Trigonal. Chemical formula: CaCO₃. Specific gravity: 2.71. Formation: Primarily formed from marine organism shells and precipitation from calcium-rich waters. Also forms from metamorphism of limestone. Common geological settings: Found in sedimentary rocks limestone, chalk , metamorphic rocks marble , and hydrothermal veins. Also in caves as stalactites and stalagmites. Common look-alikes and related entries: Quartz, Dolomite, Aragonite.
Halite vs Calcite — Compare observable properties and safer field tests.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:39:39.463918+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
The primary component of limestone and marble, calcite is one of the most widespread minerals. It reacts vigorously with dilute hydrochloric acid, making it easy to identify in the field.
How can you identify Calcite?
Compare several properties rather than relying on colour alone. This entry records colour: Colorless, white, yellow, blue, green; lustre: Vitreous to pearly; streak: White; Mohs hardness: 3; cleavage: Perfect rhombohedral 3 directions; crystal system: Trigonal; transparency: Transparent to translucent. Confirm an important identification with additional field tests or qualified laboratory work.
How does Calcite form?
Primarily formed from marine organism shells and precipitation from calcium-rich waters. Also forms from metamorphism of limestone.
Where is Calcite commonly found?
Found in sedimentary rocks limestone, chalk , metamorphic rocks marble , and hydrothermal veins. Also in caves as stalactites and stalagmites.
What is Calcite commonly confused with?
Calcite may be confused with Quartz, Dolomite, Aragonite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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