gemstone

Polished carnelian agate

Chalcedony (microcrystalline quartz), SiO₂, orange iron-oxide variety

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange to reddish-brown with pale chalcedony bands, waxy-to-glassy luster, cryptocrystalline structure, and no visible cleavage. Specific gravity is approximately 2.6.

Identified August 10, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks; iron impurities create the orange-red color. Most specimens formed in Cenozoic to older volcanic environments.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and small polished specimens; durable but generally modestly priced.

Geological facts

Carnelian is a variety of chalcedony, and its color may deepen through natural weathering or heat treatment. The pictured piece appears cut or tumbled rather than naturally weathered.

Field identification & locations

Identify it by its waxy translucency, orange color, conchoidal fracture, and hardness sufficient to scratch glass; it should not show cleavage or large quartz crystals. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.