gemstone

Tumbled carnelian

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

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, translucent to opaque, orange-red to brown-red, with vitreous to waxy luster and no visible cleavage; cryptocrystalline trigonal quartz structure. The smooth oval shape indicates tumbling and polishing.

Identified September 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron-bearing silica-rich groundwater fills cavities and fractures, with iron oxides producing the color; commonly associated with volcanic rocks and ancient river gravels, ranging from Precambrian to younger deposits.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable but less valuable than transparent gem varieties. Common polished specimens generally sell for about $3–$25, with exceptional material costing more.

Geological facts

Carnelian’s color can deepen through gentle heating or exposure to sunlight. It is often confused with dyed agate, but natural color commonly shows subtle cloudy zoning and internal reddish-brown variation.

Field identification & locations

Found commonly in India, Brazil, Uruguay, Madagascar, Germany, and the United States. Identify it by its red-orange color, translucent edges, quartz hardness, lack of cleavage, and inability to scratch glass easily; value depends on saturation, translucency, pattern, and polish.