mineral

Blue calcite (likely)

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale blue, translucent to transparent, vitreous-to-pearly luster, typically rhombohedral cleavage and trigonal crystal structure; Mohs hardness 3, specific gravity about 2.7. The blocky shape and strong cleavage are consistent with calcite, though identification from one image is uncertain.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, cavities, and sedimentary limestone deposits through precipitation from calcium-rich fluids; specimens may range from modern to hundreds of millions of years old.

Uses & applications

Used for acid-neutralizing materials, cement, aggregate, and industrial calcium carbonate; attractive blue specimens are sold as decorative or metaphysical pieces. It is generally too soft for durable jewelry.

Geological facts

Calcite effervesces readily in dilute hydrochloric acid and shows perfect rhombohedral cleavage; blue color can result from trace impurities or inclusions.

Field identification & locations

Commonly found in Mexico, Morocco, the United States, Iceland, and China. Test cautiously with vinegar or dilute acid, inspect cleavage, and avoid scratching it with metal; a gemological test is needed to distinguish it from blue fluorite or gypsum.