mineral

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange, brownish-red with white or light translucent bands; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline/cryptocrystalline); Specific gravity: 2.58-2.64.

Hardness: 6
Luster: Vitreous to waxy

Identified April 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities of volcanic rocks or ancient sedimentary formations by the deposition of silica from groundwater; its red color is caused by iron oxide (hematite) impurities.

Uses & applications

Used primarily in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for lapidary enthusiasts and collectors of semi-precious stones.

Geological facts

Carnelian has been used since the Neolithic period and was highly prized by ancient Egyptians, who believed it had protective properties. It is often heat-treated to enhance its reddish hue.

Field identification & locations

Identified in the field by its distinctive concentric or parallel banding, orange-to-red translucency, and conchoidal fracture. Commonly found in Brazil, India, Uruguay, and parts of the United States (like the Pacific Northwest).

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