mineral

Carnelian Agate

Silicon Dioxide (SiO2) with Iron Oxide impurities

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

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

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in the cavities of volcanic rocks (lavas). The reddish color is caused by iron oxide (hematite) impurities during the crystallization process.

Uses & applications

Primarily used in jewelry for cabochons and beads, ornamental carvings, seals, and as a popular semi-precious stone for collectors and lapidary artists.

Geological facts

Carnelian was used by ancient Romans to make seal rings for imprinting wax because hot wax does not stick to it. It has been used for beads since the Early Neolithic period (around 4th-5th millennium BC).

Field identification & locations

Identify in the field by its distinct translucent orange-red color and waxy surface when polished. Commonly found in Brazil, India, Madagascar, and Uruguay. Look for rounded nodules in riverbeds or within basaltic rock formations.

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