mineral

Carnelian (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Red-orange to brownish-red, Luster: Vitreous to waxy, Crystal Structure: Trigonal (cryptocrystalline), Cleavage: None, Specific Gravity: 2.58-2.64

Hardness: 6

Identified May 7, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Red-orange to brownish-red, Luster: Vitreous to waxy, Crystal Structure: Trigonal (cryptocrystalline), Cleavage: None, Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica in groundwater within volcanic rock cavities (vugs) or sedimentary environments. The red color is caused by iron oxide impurities.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads), for carvings, intaglios, and as a popular collector's mineral.

Geological facts

Carnelian was used by ancient Romans to make seal rings for imprinting wax on documents because hot wax does not stick to it. It has been used in jewelry for over 4,500 years.

Field identification & locations

Identify by its translucent waxy luster and warm orange-red hue. It is often found in riverbeds or volcanic areas. Common locations include Brazil, India, Uruguay, and Madagascar.