mineral

Tumbled blue calcite

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Usually pale blue to blue-gray with cloudy white banding, vitreous to pearly luster, Mohs hardness 3, and rhombohedral cleavage; the rounded shape indicates tumbling. The specimen’s appearance is consistent with blue calcite, though visual identification alone is not definitive.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Blue calcite forms when trace copper or other impurities color calcite-rich hydrothermal veins and carbonate deposits. Calcite is common in rocks of many ages, including limestones, marbles, and younger vein systems.

Uses & applications

Used mainly as a decorative and collectible tumbled stone; calcite is also important industrially for cement, lime, construction aggregate, and chemical manufacturing.

Geological facts

Calcite effervesces strongly in dilute hydrochloric acid and shows birefringence under polarized light. Its rhombohedral cleavage distinguishes it from similarly colored quartz, which is much harder.

Field identification & locations

Common sources include Mexico, Madagascar, Brazil, and the United States. Check for hardness, acid reaction, and cleavage; avoid confusing it with blue fluorite or dyed chalcedony.