gemstone

Tumbled carnelian (probable)

Cryptocrystalline silica, mainly chalcedony (SiO₂), colored orange-red by iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; orange-brown, translucent to opaque, with a smooth waxy-to-glassy luster and no visible cleavage. The rounded shape and polish indicate mechanical tumbling; internal banding is not apparent.

Identified August 11, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron producing the warm color; deposits are commonly Cenozoic to older, depending on locality. The specimen was subsequently cut or naturally shaped and polished.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; historically used for seals and signet stones. It has modest value unless color, translucency, pattern, and size are exceptional.

Geological facts

Carnelian is the orange-red variety of chalcedony and grades into sard when darker brown-red. Color may be enhanced by heating or dyeing, which cannot be confirmed from this image.

Field identification & locations

Common sources include India, Brazil, Uruguay, Madagascar, Botswana, and the United States. Confirm with a loupe, translucency, hardness testing, and a specific-gravity test; avoid scratching valuable material.