mineral

Polished/tumbled calcite

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Creamy white to honey-yellow, translucent, with pearly to vitreous luster and prominent curved cleavage surfaces. Mohs hardness 3, trigonal crystal structure, rhombohedral cleavage, and specific gravity about 2.71; likely polished or naturally water-worn.

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly precipitates from groundwater, hydrothermal fluids, caves, and sedimentary environments; it may range from modern deposits to rocks hundreds of millions of years old. The specimen’s rounded shape suggests human polishing or abrasion.

Uses & applications

Used in cement, lime, aggregate, soil treatment, and optical/calibration applications; attractive translucent pieces are sold as decor or mineral specimens. It is generally too soft for durable jewelry.

Geological facts

Calcite effervesces vigorously in dilute hydrochloric acid and often shows strong birefringence. Its pale honey coloration may result from iron, organic material, or other trace impurities.

Field identification & locations

Confirm with a steel nail or knife (which can scratch it) and an acid test on an inconspicuous spot; distinguish it from quartz, which is harder and does not fizz. Common worldwide, especially in limestone regions, Mexico, Iceland, and hydrothermal districts.