mineral

Calcite specimen

Calcite (calcium carbonate, CaCO₃), likely crystalline limestone or cave-calcite aggregate

AI-generated identification · may be incorrect

Typically white to cream, pearly to vitreous, with rhombohedral cleavage and Mohs hardness 3; abundant cleavage surfaces and sugary crystalline texture are visible. Specific gravity is about 2.71, and calcite effervesces vigorously in dilute hydrochloric acid.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms from precipitation in limestone caves, hydrothermal veins, marine sediments, and altered carbonate rocks. The specimen’s botryoidal/clustered form likely developed through low-temperature groundwater deposition, generally during the Cenozoic or younger.

Uses & applications

Used in cement, lime, aggregate, soil treatment, chemical manufacture, and optical/calcareous decorative specimens; collectible crystals are valued for form and luster.

Geological facts

Calcite is one of Earth’s most common minerals and can show strong double refraction in clear crystals. Its rhombohedral cleavage distinguishes it from quartz, which is harder and lacks cleavage.

Field identification & locations

Common localities include Mexico, the United States, Iceland, China, and Morocco. Test cautiously with acid, inspect cleavage, and avoid confusing it with gypsum or quartz; the exact locality cannot be confirmed from the image.