mineral

Calcite

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Pale honey-yellow to cream, translucent, with a vitreous to pearly luster and commonly rhombohedral cleavage; Mohs hardness 3 and specific gravity about 2.71. The porous, drusy appearance suggests botryoidal or scalenohedral calcite growth.

Identified August 7, 2026More mineral →

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Physical properties

Formation & geological history

Usually forms from precipitation in limestone cavities, hydrothermal veins, caves, or carbonate-rich groundwater; the specimen’s exact geological age cannot be determined from the image. It is widespread in sedimentary and hydrothermal environments.

Uses & applications

Used to manufacture cement, lime, and agricultural soil treatments, and as a flux in metallurgy; attractive crystals are collected but are generally not jewelry-hard.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid and commonly shows birefringence, producing doubled images through clear pieces. Yellow color may result from iron or other trace impurities.

Field identification & locations

Likely calcite if it scratches easily with a steel knife and reacts with dilute acid; distinguish it from gypsum, which is softer and nonreactive. Common worldwide, including Mexico, the United States, Iceland, and China.