gemstone

Carnelian

Silicon Dioxide (Chalcedony variety), SiO2

Hardness of 6.5 to 7 on the Mohs scale, orange to brownish-red color, vitreous to waxy luster, microcrystalline (cryptocrystalline) trigonal/hexagonal crystal structure, conchoidal fracture with no true cleavage, and specific gravity of approximately 2.58 to 2.64.

Identified July 29, 2026More gemstone →

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Physical properties

Formation & geological history

Formed in low-temperature environments through the deposition of silica from groundwater in cavities and fractures of pre-existing rocks, often in volcanic or sedimentary settings. Can range in geological age from millions of years old to relatively recent deposits.

Uses & applications

Widely used in jewelry making for rings, beads, and pendants, as well as for carving intaglios, cameos, and ornamental decorative objects.

Geological facts

Carnelian has been prized as a gemstone for thousands of years, with archaeological evidence showing its use in ancient Minoan Crete, ancient Egypt, and the Roman Empire where it was frequently used for signet rings due to hot wax not sticking to its surface.

Field identification & locations

Easily identified by its translucent to semi-translucent reddish-orange color and waxy luster. Common global sources include India, Brazil, Uruguay, and the United States.

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