mineral
Tumbled orange calcite
Calcite, calcium carbonate (CaCO₃)
AI-generated identification · may be incorrectTypically honey-orange to brown, translucent, and vitreous to waxy with visible cloudy banding or cleavage remnants. Mohs hardness 3; rhombohedral crystal structure, perfect rhombohedral cleavage, and specific gravity about 2.71.
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Physical properties
Typically honey-orange to brown, translucent, and vitreous to waxy with visible cloudy banding or cleavage remnants. Mohs hardness 3; rhombohedral crystal structure, perfect rhombohedral cleavage, and specific gravity about 2.71.
Formation & geological history
Forms through precipitation in limestone, hydrothermal veins, and cave deposits; orange color commonly comes from iron impurities. Calcite occurs from Precambrian to modern formations, but the specimen’s exact age cannot be determined visually.
Uses & applications
Used for cement, lime, construction aggregate, and chemical processing; attractive translucent pieces are sold as inexpensive lapidary and mineral specimens.
Geological facts
Calcite effervesces vigorously with dilute hydrochloric acid and shows strong birefringence, producing a doubled image through clear pieces. Orange calcite is often polished or tumbled for decorative use.
Field identification & locations
Likely calcite if it is noticeably softer than glass and scratches easily with a steel blade, while fizzing in weak acid; color alone is not diagnostic. Common sources include Mexico, Brazil, the United States, and Europe.
