mineral

Blue calcite

Calcite (CaCO₃), likely massive to coarsely crystalline blue calcite

AI-generated identification · may be incorrect

Pale blue, translucent to semi-transparent, with a glassy to pearly luster and visible cleavage surfaces. Mohs hardness 3; trigonal crystal structure, perfect rhombohedral cleavage, and specific gravity about 2.71.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in sedimentary limestone and marble, commonly from hydrothermal or groundwater precipitation; blue color may result from inclusions or trace impurities. Calcite ranges from Precambrian to modern formations, so age cannot be determined from appearance alone.

Uses & applications

Used for cement, lime, aggregate, soil treatment, and chemical manufacture; attractive blue specimens are sold as decorative or collectible minerals. It is generally too soft for durable jewelry.

Geological facts

Calcite effervesces vigorously in dilute hydrochloric acid and often shows strong birefringence. Blue calcite is commonly confused with blue aragonite, celestite, or fluorite.

Field identification & locations

Test cautiously with a steel point for softness and apply vinegar to a hidden surface for weak fizzing; rhombohedral cleavage is diagnostic. Common sources include Mexico, Madagascar, Brazil, and the United States.