gemstone

Polished carnelian

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

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange-red to reddish brown, with waxy/glassy luster and no visible crystals or cleavage. Its irregular polished shape and conchoidal fracture are typical of chalcedony.

Identified September 17, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, often in volcanic rocks; iron impurities produce the red-orange color. Deposits occur in relatively young to ancient volcanic and sedimentary terrains.

Uses & applications

Used for cabochons, beads, carvings, and decorative objects; common polished pieces generally have modest value.

Geological facts

Carnelian is a variety of chalcedony, colored mainly by dispersed iron oxides. Heating can intensify its orange-red coloration.

Field identification & locations

Identify it by its even waxy translucency, fine-grained texture, hardness, and lack of cleavage; common sources include India, Brazil, Uruguay, Madagascar, and Germany. It should resist scratching by a steel knife, though testing can damage the specimen.