mineral

Tumbled blue calcite

Calcite (CaCO₃), likely blue variety

AI-generated identification · may be incorrect

Pale blue to gray-white, opaque to translucent, vitreous-to-waxy luster; Mohs hardness 3, rhombohedral crystal structure, perfect rhombohedral cleavage, specific gravity about 2.71. The rounded shape indicates mechanical tumbling and obscures natural crystal form.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in sedimentary limestone, hydrothermal veins, and cavities where calcium-rich fluids precipitate calcite; blue coloration commonly reflects inclusions or trace elements. Calcite deposits range from modern to Precambrian in age.

Uses & applications

Used for ornamental tumbled stones, carving, and mineral collecting; calcite is also important industrially in cement, lime, aggregate, and soil treatment. Blue specimens have modest decorative value.

Geological facts

Calcite effervesces readily with dilute hydrochloric acid or strong vinegar, unlike most look-alike blue stones. It exhibits strong birefringence, producing doubled images when transparent.

Field identification & locations

Common sources include Mexico, Madagascar, Brazil, and the United States. Identify it by very low hardness, rhombohedral cleavage, pale blue color, and acid reaction; avoid scratching with a steel blade because it can be damaged.