mineral
Carnelian
Chalcedony (Silicon Dioxide, SiO2)
Hardness of 6.5 to 7 on the Mohs scale, orange to reddish-brown color, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity around 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, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity around 2.58 to 2.64.
Formation & geological history
Forms in low-temperature hydrothermal environments, volcanic cavities, and sedimentary rocks where silica-rich groundwater deposits microcrystalline quartz over long periods of geological time.
Uses & applications
Commonly used in lapidary work, carved into beads, cabochons, and intaglios, and collected as a semiprecious gemstone.
Geological facts
Carnelian has been used in jewelry and seals since ancient times, notably favored in ancient Rome and Egypt for signet rings because hot wax does not stick to its smooth surface.
Field identification & locations
Identified by its distinctive translucent orange-to-red coloration and waxy luster; found worldwide notably in Brazil, India, Madagascar, and the United States.
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