mineral

Carnelian

Carnelian (SiO2 - Silicon Dioxide)

Hardness: 6.5-7 (Mohs scale); Color: Orange, red, brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: Orange, red, brownish-red
Luster: Vitreous to waxy

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a cryptocrystalline variety of chalcedony, usually in volcanic and sedimentary rocks where silica-rich fluids permeate cavities. Iron oxide impurities provide the distinct color gradient.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collectors.

Geological facts

Carnelian has been used since the Neolithic period; it was highly prized in Ancient Egypt where it was believed to assist the soul in its journey to the afterlife. It was also widely used for signet rings and seals in Roman times because hot wax does not stick to it.

Field identification & locations

Identify by its translucent to semi-opaque orange-red body color and lack of banding (which distinguishes it from sardonyx or agate). Found globally in Brazil, India, Madagascar, and Uruguay. Collectors should look for even color saturation and high translucency.