mineral

Carnelian

Carnelian (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on the Mohs scale; Color: Orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Orange to reddish-brown
Luster: Vitreous to waxy

Identified March 9, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on the Mohs scale; Color: Orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64.

Formation & geological history

Formed as a cryptocrystalline variety of silica, specifically chalcedony, colored by impurities of iron oxide. It typically forms in low-temperature hydrothermal environments where silica-rich fluids permeate porous rocks or volcanic cavities.

Uses & applications

Predominantly used as a gemstone in jewelry (cabochons, beads, and rings), seal stones, cameos, and for decorative carvings. It is also a popular collector's mineral and used in metaphysical practices.

Geological facts

Carnelian has been used since the Bronze Age; ancient Romans used carnelian signet rings for sealing documents because hot wax does not stick to it. It was also found in the 4,500-year-old tombs of Ur in Mesopotamia.

Field identification & locations

Identify in the field by its distinctive translucency combined with a waxy luster and reddish-orange color. It is commonly found in India, Brazil, Uruguay, and Madagascar. In the field, look for nodules in gravel beds or weathered basalt.