gemstone

Tumbled carnelian

Carnelian, orange-red chalcedony (microcrystalline quartz; SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange to reddish-brown body with waxy/glassy luster and no visible cleavage. It has a cryptocrystalline trigonal quartz structure and conchoidal fracture; the rounded shape indicates tumbling or natural abrasion.

Identified August 25, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or veins, commonly in volcanic rocks, with iron impurities producing the orange-red color. Deposits occur in Brazil, India, Uruguay, Madagascar, Germany, and the United States; ages range from relatively young volcanic settings to ancient sedimentary formations.

Uses & applications

Used for beads, cabochons, carvings, seals, and small ornamental objects; historically valued in jewelry and signet rings.

Geological facts

Carnelian is a variety of chalcedony, often grading into sard when darker and browner. Heating can intensify or redden its color, and some commercial material is dyed.

Field identification & locations

Identify by its orange-red translucent color, waxy luster, lack of cleavage, and quartz hardness; it should resist scratching by a steel blade. The photograph alone cannot exclude orange agate or dyed chalcedony.