mineral

Blue calcite

Calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale blue, translucent to opaque rough crystal with a vitreous to pearly luster and prominent rhombohedral cleavage. Mohs hardness 3; trigonal crystal system; specific gravity about 2.7.

Identified September 24, 2026More mineral →

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Physical properties

Pale blue, translucent to opaque rough crystal with a vitreous to pearly luster and prominent rhombohedral cleavage. Mohs hardness 3; trigonal crystal system; specific gravity about 2.7.

Formation & geological history

Forms when calcium-carbonate-rich fluids precipitate in veins and cavities, and in sedimentary deposits later altered by heat or pressure. Calcite is widespread and occurs in rocks of many geological ages.

Uses & applications

Used as a decorative and collecting specimen; calcite also serves in cement and lime production, agriculture, and as a flux in industry.

Geological facts

Calcite effervesces in dilute acid and strongly double-refracts light in clear crystals.

Field identification & locations

Identify by its softness, rhombohedral cleavage, and fizzing reaction with dilute acid; blue calcite occurs in several countries, including Mexico and Madagascar. The pictured rough, pale-blue specimen is consistent with calcite.