gemstone
Carnelian
Silicon Dioxide (Chalcedony variety), SiO2
Hardness of 6.5 to 7 on the Mohs scale, orange to reddish-brown color, vitreous to waxy luster, microcrystalline (cryptocrystalline) crystal structure, conchoidal fracture, specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, orange to reddish-brown color, vitreous to waxy luster, microcrystalline (cryptocrystalline) crystal structure, conchoidal fracture, specific gravity of 2.58 to 2.64.
Formation & geological history
Formed in low-temperature hydrothermal environments, cavities of volcanic rocks, and sedimentary rocks where silica-rich groundwater precipitates quartz microcrystals. Often found in ancient river gravels and volcanic vesicles.
Uses & applications
Widely used in jewelry, cabochons, beads, rings, and historically for signet rings and intaglios due to hot wax not sticking to it.
Geological facts
Carnelian has been prized since ancient times, used by the ancient Egyptians, Romans, and Greeks. It was often placed in tombs to protect the dead in the afterlife and provide courage.
Field identification & locations
Identified by its translucent orange to red-brown color and waxy luster. Commonly found in India, Brazil, Uruguay, and the United States.
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