Carnelian (Chalcedony)

Physical Properties

Hardness: 6.5–7 on the Mohs scale; Color: Orange-red to brownish-red; Luster: Vitreous to waxy; Crystal structure: Hexagonal/trigonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.59–2.61

Formation & Geological History

Formed in low-temperature silica-rich hydrothermal environments, often filling cavities in volcanic rocks. The red-orange color is caused by the presence of iron oxide impurities (hematite).

Uses & Applications

Commonly used in jewelry as cabochons, beads, and carvings. Historically used for seals and signet rings because hot wax does not stick to it.

Geological Facts

Carnelian has been used for over 4,500 years; ancient Egyptians referred to it as the 'Setting Sun' and used it in amulets for protection. It is a variety of chalcedony.

Field Identification & Locations

Identify by its translucent orange-red glow when held to a light source and its characteristic waxy luster. Commonly found in riverbeds and beaches where volcanic rocks have eroded.

Identified on: 4/13/2026

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