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 red to orange-brown color with waxy to vitreous luster, no visible cleavage, and cryptocrystalline structure. The darker patches may be iron-oxide-rich inclusions or natural banding.

Identified August 26, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits chalcedony in volcanic cavities and fractures; iron impurities create the red coloration, often enhanced by heating. It commonly formed during relatively young to ancient volcanic episodes, depending on locality.

Uses & applications

Used for beads, cabochons, carvings, seals, and polished decorative specimens; inexpensive jewelry and lapidary material.

Geological facts

Carnelian was widely used in ancient Egyptian, Greek, and Roman jewelry and engraved signet rings. Its color can deepen through controlled heat treatment.

Field identification & locations

Identify it by its even red-orange color, translucency, waxy polish, and hardness sufficient to scratch glass; it should not show obvious crystal faces. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.