gemstone

Tumbled carnelian (orange chalcedony)

Carnelian, a microcrystalline variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange, amber, or reddish-brown color with waxy to vitreous luster. Lacks visible crystal faces and has conchoidal fracture; the smooth surface indicates tumbling and polishing.

Identified August 26, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; iron impurities create the orange-red color. Deposits range from Cenozoic to older geological ages, depending on locality.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and inexpensive collectible specimens; historically valued as an engraving stone.

Geological facts

Carnelian is chalcedony colored primarily by finely dispersed iron oxides or hydroxides. Heating can intensify its orange-red coloration, and some commercial material is dyed.

Field identification & locations

Identify it by its uniform orange coloration, translucency, waxy polish, and quartz hardness; it should scratch ordinary glass but not be scratched by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.