mineral

Orange calcite (likely iron-stained calcite)

Calcite, calcium carbonate (CaCO₃), colored by iron-oxide inclusions

AI-generated identification · may be incorrect

Typically Mohs hardness 3, vitreous to pearly luster, white-to-orange color, rhombohedral cleavage, and specific gravity about 2.71. The specimen appears rough, massive, and strongly orange-red from iron staining; crystal form is not clearly visible.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms in limestone, hydrothermal veins, caves, and carbonate-rich sedimentary environments through precipitation from groundwater or mineral-bearing fluids. Calcite deposits range from modern to Precambrian in age.

Uses & applications

Used in cement, lime, aggregate, soil treatment, and chemical industries; attractive orange specimens are collected or used decoratively. It is generally inexpensive unless unusually vivid, crystalline, or large.

Geological facts

Calcite effervesces vigorously with dilute hydrochloric acid or vinegar, though vinegar may react slowly. Its rhombohedral cleavage and ability to scratch with a copper coin help distinguish it from harder orange minerals.

Field identification & locations

Common worldwide, including Mexico, the United States, Brazil, China, and Morocco. Test an inconspicuous area with acid and check whether it scratches with a steel knife; avoid confusing it with orange quartz, which is much harder.