mineral

Blue calcite

Calcite (CaCO₃), likely blue calcite

AI-generated identification · may be incorrect

Pale blue-gray, cloudy/translucent, with a vitreous to pearly luster and prominent rhombohedral cleavage; Mohs hardness 3, specific gravity about 2.71. The irregular broken surfaces and white crystalline patches are consistent with calcite, though the photograph alone cannot exclude blue-gray aragonite or coated materi…

Identified August 27, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly forms in sedimentary limestones, hydrothermal veins, and cavities; blue color may result from trace impurities or inclusions. It forms from relatively low-temperature fluids and can range from ancient to geologically recent.

Uses & applications

Used in cement, lime, aggregate, soil treatment, and chemical production; attractive blue specimens are sold for décor and mineral collecting rather than fine jewelry because they are soft and easily scratched.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid or vinegar, though vinegar may react slowly. It commonly shows birefringence, producing doubled text when placed over printed writing.

Field identification & locations

Likely identification requires a hardness test and acid reaction: it should scratch with a steel knife and fizz with acid. Common localities include Mexico, the United States, Peru, and China.