mineral

Calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

White to honey-colored, translucent to opaque crystals with vitreous to pearly luster; commonly rhombohedral or scalenohedral, though this specimen appears as intergrown cleavage fragments. Mohs hardness 3, perfect rhombohedral cleavage, specific gravity about 2.71.

Identified September 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, caves, sedimentary limestones, and cavities in volcanic rocks through precipitation from carbonate-rich fluids. Its exact geological age and locality cannot be determined from the image.

Uses & applications

Used in cement, lime, aggregate, glass manufacture, and chemical industries; attractive crystal clusters are collected as mineral specimens. It is generally not suitable for jewelry because of its low hardness and perfect cleavage.

Geological facts

Calcite strongly effervesces in dilute hydrochloric acid and displays double refraction when clear. Color commonly results from iron, organic matter, or other trace impurities.

Field identification & locations

Identify by its very soft surface, rhombohedral cleavage, and vigorous acid reaction; it is commonly found worldwide in limestone regions and mineral veins. Avoid vinegar-based tests if preservation matters, as acids can etch it.