gemstone

Carnelian

Carnelian Agate (SiO2)

Hardness: 6.5-7 on 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
Color: Reddish-orange to brownish-red
Luster: Vitreous to waxy

Identified July 5, 2026More gemstone →

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Physical properties

Hardness: 6.5-7 on 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 by the deposition of silica from groundwater in the cavities of igneous rocks, primarily volcanic lavas. The color comes from iron oxide impurities.

Uses & applications

Extensively used in jewelry making, lapidary arts, beadwork, and historical seal stones.

Geological facts

Carnelian was used by ancient Egyptians for amulets and by Romans to carve signet rings because hot wax does not stick to it.

Field identification & locations

Identified by its translucency and uniform reddish-brown hue. Common in Brazil, India, and Uruguay. Look for a waxy luster and conchoidal fracture in the field.