mineral

Blue calcite (likely)

Calcite, CaCO₃

AI-generated identification · may be incorrect

Pale blue-gray with white patches and a vitreous-to-pearly luster; calcite has trigonal crystals, perfect rhombohedral cleavage, Mohs hardness 3, and specific gravity about 2.7. The photo’s small, rough specimen is consistent with calcite, though identification from appearance alone is uncertain.

Identified October 6, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium carbonate precipitates from water or in limestone and hydrothermal settings; calcite occurs in rocks of many ages. Blue coloration commonly reflects trace impurities or inclusions.

Uses & applications

Used in cement, lime, and other industrial products; attractive blue specimens are collected or used decoratively, but are generally too soft for durable jewelry.

Geological facts

Calcite effervesces in dilute acid and is softer than a copper coin; clear calcite can show strong double refraction.

Field identification & locations

Look for rhombohedral cleavage and a scratchable surface, then confirm with an acid test on a tiny inconspicuous spot. Common worldwide, especially in limestone and hydrothermal veins.