gemstone

Polished carnelian agate

Chalcedony (microcrystalline quartz, SiO₂), orange-red variety with agate banding

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange, red, and cream banding; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage; specific gravity about 2.6. The specimen appears polished and possibly carved or tumbled.

Identified September 4, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing layered chalcedony and iron-colored bands. Agate formation commonly occurred from the late Paleozoic through Cenozoic eras, depending on locality.

Uses & applications

Used for cabochons, beads, carvings, seals, ornaments, and small decorative objects; durable enough for jewelry and ornamental stonework.

Geological facts

Carnelian’s orange-red color generally comes from iron oxides. Concentric or wavy banding indicates agate rather than uniformly colored chalcedony.

Field identification & locations

Identify by its warm orange-red translucency, curved bands, glassy/waxy surface, and lack of cleavage; it commonly occurs in volcanic regions of Brazil, Uruguay, India, Madagascar, and the United States.