mineral

Calcite crystal

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Typically pale yellow to greenish-yellow, translucent, with vitreous to pearly luster and rhombohedral cleavage; Mohs hardness 3, specific gravity about 2.71. The specimen appears as a rough, blocky cleavage fragment rather than a complete crystal.

Identified August 7, 2026More mineral →

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Physical properties

Formation & geological history

Forms in sedimentary limestones, hydrothermal veins, caves, and metamorphic marbles. Calcite deposits range from Precambrian to modern, though the specimen’s age cannot be determined visually.

Uses & applications

Used to manufacture cement, lime, aggregate, glass, and agricultural soil treatments; transparent crystals are collected and occasionally used as decorative specimens.

Geological facts

Calcite effervesces strongly in dilute hydrochloric acid and shows distinctive double refraction in clear pieces. Its color may result from trace iron, sulfur, organic matter, or other impurities.

Field identification & locations

Identify it by its softness, rhombohedral cleavage, and acid reaction; distinguish it from quartz, which is harder and lacks cleavage. Common worldwide, especially in limestone regions, hydrothermal veins, and caves.