mineral

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Hardness: 6.5-7 on Mohs scale; Color: Red-orange to brownish-red; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Color: Red-orange to brownish-red
Luster: Vitreous to waxy

Identified May 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The red tint is caused by iron oxide (hematite) impurities.

Uses & applications

Primarily used in jewelry (cabochons, beads), decorative carvings, and lapidary arts. It has been used for signet rings and seals throughout history.

Geological facts

Carnelian was used by the ancient Egyptians as a symbol of life and to accompany the deceased on their journey to the afterlife. It was often set into gold for royalty.

Field identification & locations

Identify in the field by its translucent properties when held to light and its distinctive conchoidal (shell-like) fracture. Commonly found in Brazil, India, Uruguay, and Madagascar.

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