mineral

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

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

Hardness: 6

Identified April 4, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks. Its red color is derived from iron oxide impurities. It occurs globally across various geological ages.

Uses & applications

Used primarily in lapidary work, jewelry (beads, cabochons, intaglios), and as decorative stones or pocket stones for collectors.

Geological facts

Carnelian has been used for over 4,500 years; ancient Sumerians and Egyptians used it for cylinder seals and amulets. It was also highly valued by Roman warriors who believed it granted them courage and power.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture, and orange-to-red translucency. Commonly found in riverbeds, beaches, and volcanic regions (notably in Brazil, India, and the Pacific Northwest of the USA).

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