mineral

Calcite crystal fragment

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Typically colorless, white, honey, or brown with vitreous to pearly luster; Mohs hardness 3, perfect rhombohedral cleavage, and trigonal crystal structure. The specimen appears translucent with prominent cleavage faces and possible iron-oxide staining.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Calcite precipitates from groundwater, hydrothermal fluids, caves, veins, and sedimentary limestones. Its age cannot be determined from the image and may range from recent cave growth to ancient mineralization.

Uses & applications

Used in cement, lime, aggregate, glass manufacture, agriculture, and chemical processing; clear crystals are collected and occasionally used as decorative specimens.

Geological facts

Calcite strongly effervesces in dilute hydrochloric acid and shows double refraction in transparent pieces. Its cleavage fragments commonly form slanted rhombohedra rather than cubic pieces.

Field identification & locations

Look for softness, rhombohedral cleavage, and vigorous acid reaction; common localities include limestone regions, Mexico, Iceland, and hydrothermal vein districts. Identification is uncertain because the image shows only a fragment.