gemstone

Tumbled carnelian agate

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-brown body with waxy to vitreous luster, conchoidal fracture, and no cleavage. The smooth rounded shape indicates mechanical tumbling and polishing.

Identified September 17, 2026More gemstone →

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Physical properties

Hardness 6.5–7 Mohs; translucent orange-brown body with waxy to vitreous luster, conchoidal fracture, and no cleavage. The smooth rounded shape indicates mechanical tumbling and polishing.

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony and iron-bearing material; commonly Cenozoic to older, depending on deposit. Heat and oxidation intensify the red-orange color.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; polished pieces are popular mineral-shop specimens.

Geological facts

Carnelian is an orange-red variety of chalcedony and may grade into banded agate. Color can be enhanced by heating or dyeing, so untreated status is difficult to confirm visually.

Field identification & locations

Identify by its warm orange color, translucency, glassy/waxy surface, and lack of visible crystal faces; it should not scratch easily with a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.