mineral

Carnelian Agate

Carnelian (Silicon Dioxide: SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Orangish-red to translucent yellow-brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Orangish-red to translucent yellow-brown
Luster: Vitreous to waxy

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in low-temperature hydrothermal environments where silica-rich fluids deposit in volcanic rock cavities or sedimentary layers. The reddish hue comes from iron oxide impurities (hematite).

Uses & applications

Used primarily in lapidary arts, jewelry (beads, cabochons), and as a popular pocket stone for collectors. Historically used for cylinder seals and signet rings.

Geological facts

Carnelian was highly prized in Ancient Egypt, where it was thought to provide protection for the soul in the afterlife. It is the translucent variety of chalcedony.

Field identification & locations

Identify in the field by its waxy luster, orange coloration, and inability to be scratched by a steel pocketknife. Commonly found in Brazil, India, Uruguay, and Madagascar.