mineral

Calcite crystal cluster

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale honey-brown, translucent-to-opaque crystals with prominent rhombohedral cleavage and a vitreous to pearly luster; Mohs hardness 3. The photo is blurry, so the identification is provisional.

Identified October 13, 2026More mineral →

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Physical properties

Pale honey-brown, translucent-to-opaque crystals with prominent rhombohedral cleavage and a vitreous to pearly luster; Mohs hardness 3. The photo is blurry, so the identification is provisional.

Formation & geological history

Calcite commonly forms when calcium-carbonate-rich fluids precipitate in veins, cavities, or sedimentary rocks; such deposits range from recent to hundreds of millions of years old.

Uses & applications

Used in cement and lime production, as a flux and soil amendment, and as a collector mineral; attractive crystals may be displayed.

Geological facts

Calcite effervesces in dilute acid and is strongly birefringent in clear crystals.

Field identification & locations

Look for blocky crystals that cleave into rhombohedrons and are easily scratched by a knife. Calcite occurs worldwide, especially in limestone and hydrothermal veins.