gemstone

Carnelian

Carnelian Agate (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brownish-red; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal; microcrystalline); Cleavage: None (conchoidal fracture).

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

Identified July 13, 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: Hexagonal (trigonal; microcrystalline); Cleavage: None (conchoidal fracture).

Formation & geological history

Formed by the deposition of silica from groundwater in the cavities of igneous rocks such as basalt or rhyolite. The reddish tint comes from iron oxide impurities (hematite).

Uses & applications

Primarily used as a gemstone for jewelry, beads, cabochons, and decorative carvings; historically used for signet rings and wax seals.

Geological facts

In ancient times, carnelian was believed to protect the wearer and grant courage. It was one of the first gemstones used by many ancient civilizations, including the Sumerians and Egyptians.

Field identification & locations

Identify by its translucent, waxy appearance and orange-red hues. Commonly found in Brazil, India, Uruguay, and Madagascar. It can be distinguished from red jasper by its translucency.