gemstone

Tumbled carnelian

Carnelian, a red-orange variety of chalcedony (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent reddish-brown to orange color, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The smooth rounded surface indicates mechanical tumbling and polishing.

Identified August 10, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron impurities color silica-rich chalcedony, commonly filling cavities and fractures in volcanic rocks or occurring as nodules in sedimentary deposits. Most specimens are Cenozoic or older, but exact age depends on locality.

Uses & applications

Used for beads, cabochons, carvings, and inexpensive jewelry; polished pieces are also popular mineral-collection specimens. It is not generally used as a construction material.

Geological facts

Carnelian’s color ranges from pale orange to deep reddish brown, with stronger red tones produced by oxidized iron. Heat treatment can intensify or alter its color.

Field identification & locations

Identify it by its uniformly waxy, translucent red-orange appearance, lack of cleavage, and quartz-like hardness; it should scratch glass but not be scratched by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.