gemstone

Tumbled carnelian

Carnelian, orange chalcedony (microcrystalline SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange to reddish-brown, waxy-to-glassy luster, cryptocrystalline quartz with no cleavage and conchoidal fracture. The pale curved bands suggest chalcedony layering or iron-oxide zoning.

Identified August 21, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron impurities producing the orange-red color; commonly Cenozoic to older volcanic and sedimentary settings. This specimen has been cut and polished/tumbled.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive jewelry; also collected as a decorative gemstone.

Geological facts

Carnelian is a variety of chalcedony, not a separate mineral species; heating can intensify its red-orange color by oxidizing iron.

Field identification & locations

Identify by its smooth waxy surface, translucency, orange color, quartz hardness, and lack of cleavage; common sources include India, Brazil, Uruguay, Madagascar, and Botswana. A steel file should not easily scratch it.