gemstone

Polished carnelian

Carnelian, orange-red cryptocrystalline quartz (SiO₂), chalcedony variety

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange to reddish-brown color, waxy to vitreous luster, and no visible crystal faces. It has conchoidal fracture, no cleavage, and specific gravity around 2.60–2.65; the surface appears polished and may show natural inclusions or color zoning.

Identified August 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits chalcedony in volcanic cavities, fractures, or sedimentary voids; iron oxides produce the orange-red color. Deposits range from ancient to relatively recent and occur worldwide.

Uses & applications

Used for beads, cabochons, seals, pendants, and ornamental carvings; historically valued in signet rings and amulets. Common polished pieces generally have modest commercial value.

Geological facts

Carnelian is a microcrystalline quartz aggregate rather than a single large crystal. Some material is heat-treated or dyed to intensify its red-orange color.

Field identification & locations

Common localities include India, Brazil, Uruguay, Madagascar, Germany, and the United States. Identification features are its orange-red translucency, waxy polish, hardness, and lack of cleavage; glass and plastic are common imitations.