mineral

Blue calcite (probable)

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale blue, cloudy, and translucent to opaque with a vitreous-to-pearly luster; Mohs hardness 3, rhombohedral crystal structure, and perfect rhombohedral cleavage. The rough surface and color are consistent with blue calcite, though aragonite or blue fluorite are alternatives without testing.

Identified August 9, 2026More mineral →

Explore Blue calcite (probable) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Typically forms in hydrothermal veins, cavities, and sedimentary carbonate environments when calcium-rich fluids precipitate calcite; specimens may range from ancient sedimentary deposits to young vein fillings.

Uses & applications

Used mainly as a mineral specimen or ornamental stone; calcite is also important industrially in cement, lime, aggregate, and agricultural soil treatment. Blue material has modest decorative value.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid or vinegar, especially when powdered; it also shows double refraction through clear areas. Its blue color commonly reflects trace impurities or inclusions.

Field identification & locations

Commonly found in Mexico, the United States, Peru, China, and Madagascar. Confirm by its very low hardness— it can be scratched with a copper coin or steel knife—and rhombohedral cleavage; fluorite is harder (Mohs 4) and commonly cleaves into octahedra.