mineral

Polished carnelian/chalcedony

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

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent orange-brown to red, with waxy-to-glassy luster and no visible cleavage. The rounded, polished surface and cloudy internal banding are typical of chalcedony; small cavities or inclusions may occur.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, precipitating cryptocrystalline quartz. It commonly formed during the Cenozoic and older volcanic episodes, with major sources in India, Brazil, Uruguay, Madagascar, and Germany.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary collections; historically used for seals and signet rings.

Geological facts

Carnelian’s color commonly comes from finely dispersed iron oxides; heating can intensify its red-orange tone. It is a traditional gemstone associated with vitality and protection.

Field identification & locations

Identify it by its orange-red translucent body, waxy luster, conchoidal fracture, and inability to scratch with a steel knife; quartz should scratch glass. The image may also represent similarly colored jasper or agate, which require testing for a precise identification.