gemstone

Carnelian

Chalcedony (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, reddish-orange to brown color due to iron oxide impurities, vitreous to waxy luster, microcrystalline or cryptocrystalline crystal structure (quartz variety), conchoidal fracture with no true cleavage, and specific gravity of approximately 2.60 to 2.65.

Identified August 5, 2026More gemstone →

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Physical properties

Formation & geological history

Forms primarily as low-temperature hydrothermal solutions deposit silica within cavities of volcanic or sedimentary rocks, often occurring over millions of years in alluvial gravels and river beds where pebbles are naturally tumbled and smoothed.

Uses & applications

Widely used in jewelry making, carved intaglios, signet rings, beads, and as an ornamental gemstone prized since ancient times.

Geological facts

Carnelian has a rich history dating back to ancient Egypt, where it was often placed in tombs to assist the dead in their journey to the afterlife, and it was heavily favored by Roman soldiers for engraved signet rings because hot wax would not stick to it.

Field identification & locations

Easily identified by its translucent reddish-orange to brownish hue, waxy luster, and conchoidal breakage. Commonly found worldwide including Brazil, India, Madagascar, and the United States, often collected from riverbeds and beaches.