mineral
Tumbled amber-colored stone, possibly orange calcite or carnelian
Indeterminate from image; likely calcite (CaCO₃) or chalcedony (SiO₂)
AI-generated identification · may be incorrectSmall, rounded and polished, translucent orange-brown with a waxy to vitreous luster. Calcite has Mohs hardness 3 and rhombohedral cleavage; carnelian has hardness 6.5–7 and cryptocrystalline quartz structure.
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Physical properties
Small, rounded and polished, translucent orange-brown with a waxy to vitreous luster. Calcite has Mohs hardness 3 and rhombohedral cleavage; carnelian has hardness 6.5–7 and cryptocrystalline quartz structure.
Formation & geological history
Calcite may form in hydrothermal veins or sedimentary cavities; carnelian forms when silica-rich fluids fill volcanic cavities. A specimen’s age cannot be determined visually.
Uses & applications
Commonly sold as a decorative tumbled stone, craft material, or inexpensive collector specimen; carnelian is also used in jewelry.
Geological facts
The color may result from iron impurities. A polished surface and isolated appearance indicate human processing rather than a natural outcrop fragment.
Field identification & locations
Test cautiously: calcite scratches with a steel knife and fizzes in dilute hydrochloric acid; carnelian does not fizz and resists scratching. Common sources include Brazil, India, Madagascar, Mexico, and the United States.
