mineral

Calcite crystal cluster

Calcite (calcium carbonate, CaCO₃), likely honey or pale-orange calcite

AI-generated identification · may be incorrect

Typically Mohs hardness 3, white to cream/yellow-orange color, vitreous to pearly luster, rhombohedral crystal structure and perfect rhombohedral cleavage; specific gravity about 2.71. The specimen shows many intergrown, somewhat scalenohedral/rhombohedral crystals with iron-oxide staining.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly precipitates from groundwater or hydrothermal fluids in cavities, veins, caves, and carbonate rocks. Its exact age cannot be determined from the photograph; deposits range from recent to Paleozoic and older.

Uses & applications

Used industrially for cement, lime, aggregate, soil treatment, and chemical manufacture; transparent crystals are collectible but generally not gemstone-grade.

Geological facts

Calcite strongly effervesces in dilute hydrochloric acid and commonly exhibits double refraction in clear pieces. Orange coloration often results from iron impurities or surface staining.

Field identification & locations

Identify it by its softness, rhombohedral cleavage, and vigorous acid reaction; it is commonly found in limestone cavities, hydrothermal veins, and geodes worldwide. Avoid scratching or washing with acid if preservation is important.