gemstone

Tumbled carnelian

Carnelian, a translucent orange-red variety of chalcedony (microcrystalline quartz), SiO₂

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to vitreous luster, orange-brown to red color, and no visible cleavage; cryptocrystalline quartz has a trigonal structure. The rounded, glossy surfaces indicate tumbling and polishing.

Identified September 13, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron impurities color silica-rich chalcedony, commonly filling cavities and fractures in volcanic rocks. Deposits occur in Brazil, India, Uruguay, Madagascar, and the United States; individual pieces are generally geologically young relative to their host rocks.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable tumbled pieces are popular inexpensive collectibles. Historically it was used in signet rings and amulets.

Geological facts

Carnelian’s color can deepen after gentle heating or prolonged sunlight exposure because iron oxides become more strongly expressed.

Field identification & locations

Identify it by its translucent orange-red color, smooth waxy appearance, lack of cleavage, and ability to scratch glass; avoid confusing it with dyed agate or orange glass. Natural banding or cloudy internal texture supports chalcedony identification.