mineral

Likely blue calcite

Calcite, CaCO₃

AI-generated identification · may be incorrect

Small rough blue, translucent-to-opaque piece with a vitreous to pearly luster; calcite has trigonal crystal structure, perfect rhombohedral cleavage, Mohs hardness 3, and specific gravity about 2.7. Color alone is not diagnostic; the image does not show enough detail to confirm the identification.

Identified October 1, 2026More mineral →

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Physical properties

Formation & geological history

Blue calcite forms when calcium-carbonate-rich fluids precipitate or alter limestone and related rocks; specimens can occur in veins and cavities. Its age depends on the deposit and cannot be determined from the image.

Uses & applications

Commonly sold as a decorative or collecting stone and sometimes carved; calcite is also an important industrial source of lime and cement ingredients.

Geological facts

Calcite strongly effervesces in dilute acid and is much softer than quartz, making those useful distinguishing tests on an inconspicuous spot.

Field identification & locations

The pale blue color and rough, cleavage-like surfaces are consistent with blue calcite, but confirm with hardness and cleavage tests; similar-looking blue minerals are possible. Found in carbonate deposits worldwide.