mineral

Calcite specimen, possibly manganocalcite

Calcite (CaCO₃), with possible manganese/iron impurities

AI-generated identification · may be incorrect

Likely hardness 3 Mohs; pale cream to pink-brown, vitreous to pearly luster, abundant rhombohedral cleavage, and translucent crystalline areas. The dark patches may be matrix or sulfide inclusions; exact identification needs testing.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly forms in hydrothermal veins, carbonate rocks, caves, and mineralized cavities from groundwater or hot fluids; deposits range from ancient to modern. Pink coloration can result from manganese substitution, while brown tones may reflect iron or surface staining.

Uses & applications

Used industrially for cement, lime, aggregate, optical calcite, and chemical production; attractive crystals are collected, though this rough specimen has limited gem use.

Geological facts

Calcite effervesces strongly in dilute hydrochloric acid and can often be scratched with a copper coin or steel blade. Its rhombohedral cleavage distinguishes it from quartz, which is harder and lacks cleavage.

Field identification & locations

Common worldwide in limestone and mineral veins, including Mexico, the United States, Brazil, and China. Confirm with a hardness test, cleavage observation, and acid reaction; the image alone cannot reliably separate calcite from similar carbonates.