mineral

Calcite crystal cluster

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Likely calcite with creamy-white to honey-brown color, vitreous to pearly luster, prominent rhombohedral cleavage, and blocky/scalenohedral crystals. Mohs hardness 3; specific gravity about 2.71; commonly nonmetallic and may effervesce strongly in dilute hydrochloric acid.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium-rich groundwater or hydrothermal fluids precipitate carbonate in cavities, veins, caves, and sedimentary rocks; the specimen’s exact age and locality cannot be determined from the image.

Uses & applications

Used industrially for cement, lime, aggregate, soil treatment, and chemical production; transparent or well-formed crystals are collected and occasionally used as decorative specimens.

Geological facts

Calcite is one of the most common minerals and has excellent rhombohedral cleavage, allowing fragments to break into slanted blocks. It is optically birefringent, producing double images through clear crystals.

Field identification & locations

Identify by its hardness, rhombohedral cleavage, pale color, and acid reaction; distinguish it from quartz because calcite is much softer. Common localities include Mexico, Iceland, the United States, China, and Morocco.