mineral

Calcite crystal

Calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale yellow-green, translucent, and vitreous to pearly, with prominent rhombohedral cleavage; Mohs hardness 3, specific gravity about 2.71. The rough, blocky form is consistent with massive or poorly developed calcite crystals.

Identified August 7, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly precipitates from groundwater, hydrothermal fluids, and marine sediments, forming in limestone cavities, veins, and geodes. Its age may range from very recent deposits to Precambrian rocks, depending on locality.

Uses & applications

Used to manufacture cement, lime, agricultural soil conditioners, and chemical products; transparent crystals are collected and occasionally used as decorative specimens. This small rough piece generally has modest commercial value.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid or vinegar, especially when freshly powdered or scratched. It shows birefringence: clear pieces can produce doubled images when placed over text.

Field identification & locations

Common worldwide in limestone regions, hydrothermal veins, caves, and geodes; notable localities include Mexico, Iceland, the United States, and China. Confirm it with a hardness test, rhombohedral cleavage, and acid reaction, while distinguishing it from softer gypsum.