mineral

Orange calcite

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3, pearly to vitreous luster, orange to honey color, white streak, and excellent rhombohedral cleavage; crystals are trigonal, though this specimen appears massive and cleaved. It may show translucency and effervesces vigorously with dilute hydrochloric acid.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium-rich groundwater precipitates carbonate, or in hydrothermal veins, cavities, and sedimentary limestones; individual specimens may range from recent to hundreds of millions of years old. The orange color commonly reflects iron or other trace impurities.

Uses & applications

Used industrially for cement, lime, aggregate, soil treatment, and chemical production; attractive transparent pieces are collected or occasionally used as decorative material, but this rough specimen has modest gem value.

Geological facts

Calcite is one of Earth’s most abundant minerals and exhibits strong birefringence, producing double images through clear pieces. Orange calcite is commonly confused with orange aragonite or honey-colored gypsum.

Field identification & locations

Identify by its very soft surface, rhombohedral cleavage, white streak, and acid reaction; common localities include Mexico, Peru, the United States, and parts of Europe. A hardness test and acid test distinguish it from harder quartz and nonreactive feldspar.