mineral
Blue calcite (likely polished/tumbled)
Calcite — calcium carbonate, CaCO₃
AI-generated identification · may be incorrectPale 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.
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Physical properties
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.
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.
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