gemstone

Tumbled carnelian/chalcedony

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

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange to red-brown color, vitreous to waxy luster, no visible crystals, and conchoidal fracture. The rounded surface indicates mechanical tumbling and polishing.

Identified August 30, 2026More gemstone →

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Physical properties

Mohs hardness 6.5–7; translucent orange to red-brown color, vitreous to waxy luster, no visible crystals, and conchoidal fracture. The rounded surface indicates mechanical tumbling and polishing.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron impurities producing the red-orange color; deposits range from ancient volcanic-hosted occurrences to younger alluvial gravels. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.

Uses & applications

Used for beads, cabochons, carvings, seals, and inexpensive jewelry; polished pieces are popular decorative and lapidary materials.

Geological facts

Carnelian is one of the oldest gemstone materials used by humans, including in ancient Egyptian and Roman beads and signet rings. Heating can intensify its reddish color.

Field identification & locations

Identify it by its uniform orange-red body color, translucency, very high polish, hardness, and lack of cleavage; it should scratch glass but not be scratched easily by steel. A small tumbled piece typically sells for $2–$15; finer translucent or strongly banded specimens may reach $20–$75.