gemstone

Tumbled carnelian (orange chalcedony)

Carnelian, a microcrystalline variety of quartz; SiO₂, commonly colored by iron oxides

AI-generated identification · may be incorrect

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

Identified August 31, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron producing the orange-red color; deposits range from Paleozoic to Cenozoic in age. Common sources include India, Brazil, Uruguay, Madagascar, and parts of the western United States.

Uses & applications

Used for beads, cabochons, carvings, and inexpensive jewelry; historically used for seals and ornamental objects. It has little industrial use beyond decorative silica material.

Geological facts

Carnelian is a variety of chalcedony, itself a form of quartz. Heating can intensify its red-orange color, and some commercial material is dyed or heat-treated.

Field identification & locations

Identify it by its uniform orange color, translucency, waxy luster, and quartz hardness; it should resist scratching from a steel knife. Natural banding or inclusions may help distinguish it from dyed glass or plastic.