mineral

Likely calcite specimen

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale honey-yellow to cream, translucent, with a glassy-to-pearly luster and prominent rhombohedral cleavage; Mohs hardness 3 and specific gravity about 2.71. The irregular form and granular texture may also indicate calcite-rich limestone or aragonite, but the image is not diagnostic.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly precipitates from groundwater, hydrothermal fluids, caves, and sedimentary environments; deposits range from ancient to modern. Its amber coloration may result from iron or organic impurities.

Uses & applications

Used in cement, aggregate, lime, soil treatment, and chemical production; transparent crystals are collectible, though this small rough piece has modest value.

Geological facts

Calcite effervesces strongly in dilute hydrochloric acid or vinegar, though vinegar may react slowly. It commonly shows birefringence, producing doubled images through clear pieces.

Field identification & locations

Look for rhombohedral cleavage, relatively low hardness, and acid fizz; distinguish it from quartz, which is harder and does not fizz. Common worldwide, especially in limestone regions, Mexico, Iceland, the United States, and hydrothermal districts.