mineral

Blue calcite (likely polished/tumbled)

Calcite — calcium carbonate, CaCO₃

AI-generated identification · may be incorrect

Pale blue, waxy to pearly luster with visible curved cleavage/fracture lines; Mohs hardness 3, trigonal crystal system, and perfect rhombohedral cleavage. The rounded shape indicates tumbling or polishing.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms in sedimentary limestone, hydrothermal veins, and cavities, commonly gaining blue color from trace elements or inclusions. Calcite ranges from modern deposits to rocks hundreds of millions of years old.

Uses & applications

Used as a collectible or decorative stone; calcite is also important industrially for cement, lime, aggregate, glass, and soil treatment. Blue material has limited jewelry use because it scratches easily.

Geological facts

Calcite effervesces strongly in cold dilute hydrochloric acid and shows double refraction in clear pieces. It is softer and more cleavage-prone than quartz.

Field identification & locations

Common localities include Mexico, South Africa, Brazil, the United States, and Peru. Confirm with a hardness test against a copper coin and acid reaction; the image alone cannot exclude blue aragonite or dyed material.