mineral

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Hardness: 6.5-7.0 (Mohs); Color: Reddish-orange, brown, pinkish; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Trigonal, microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Reddish-orange, brown, pinkish
Luster: Vitreous to waxy

Identified May 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7.0 (Mohs); Color: Reddish-orange, brown, pinkish; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Trigonal, microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed in volcanic cavities or sedimentary environments through the deposition of silica in groundwater. The orange-red color is caused by the presence of iron oxide (hematite).

Uses & applications

Used primarily in lapidary work, jewelry (beads, cabochons), carvings, and as a semi-precious collector's stone.

Geological facts

Carnelian was highly prized in ancient cultures; the Romans used it for signet rings and the Egyptians believed it could calm anger or ward off the 'evil eye'.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture, and translucency. It is common in riverbeds and coastal regions of Brazil, India, and Uruguay. Use a light source to check for uniform translucency versus opaque spots.

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