gemstone

Carnelian

Silicon Dioxide (Chalcedony variety), SiO2

Hardness: 6.5-7 on the Mohs scale; Color: Orange, reddish-orange, brownish-red; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.58-2.64

Hardness: 6
Color: Orange, reddish-orange, brownish-red
Luster: Vitreous to waxy

Identified July 28, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in silica-rich solutions filling cavities in volcanic and sedimentary rocks, often through low-temperature hydrothermal deposition or groundwater percolation in volcanic environments.

Uses & applications

Widely used for making tumbled stones, beads, cabochons for rings and pendants, and carved into intaglios and seals since ancient times.

Geological facts

Carnelian was highly prized in ancient Egypt, where it was often worn by architects to show their rank and placed in tombs to help the dead transition into the afterlife.

Field identification & locations

Can be identified by its distinctive translucent reddish-orange color, waxy luster, and conchoidal fracture. Found globally, with notable deposits in Brazil, India, Madagascar, and the United States.

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