mineral

Calcite crystal cluster

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Typically hardness 3, vitreous to pearly luster, white to honey-orange color, translucent appearance, and prominent rhombohedral cleavage; crystals are trigonal. The orange coloration likely comes from iron-oxide staining or included impurities.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, limestone cavities, caves, and sedimentary environments through precipitation from carbonate-rich fluids. The specimen’s exact geological age and locality cannot be determined from the image.

Uses & applications

Used industrially for cement, lime, aggregate, and chemical production; attractive clusters are sold as display minerals. It is generally unsuitable for jewelry because of its softness and perfect cleavage.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid or vinegar, though vinegar may react slowly. It commonly shows double refraction, making text appear doubled when viewed through a clear fragment.

Field identification & locations

Identify by its low hardness, rhombohedral cleavage, pale color, and acid reaction; distinguish it from quartz, which is harder and lacks cleavage. Common worldwide, especially in Mexico, the United States, China, and Europe.