mineral
Carnelian Agate
Silicon Dioxide (SiO2) - Chalcedony variety
Hardness of 6.5 to 7 on the Mohs scale; color ranges from yellowish-orange to brownish-red; vitreous to waxy luster; cryptocrystalline structure; conchoidal fracture with no true cleavage; specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale; color ranges from yellowish-orange to brownish-red; vitreous to waxy luster; cryptocrystalline structure; conchoidal fracture with no true cleavage; specific gravity of 2.58 to 2.64.
Formation & geological history
Forms primarily in cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years. The reddish coloration is due to iron oxide impurities.
Uses & applications
Widely used for making gemstones, beads, cabochons, carved ornaments, and historical signet rings.
Geological facts
Carnelian has been prized since ancient times, frequently used in ancient Rome and Egypt for signet rings and amulets because hot wax would not stick to the smooth surface of the stone.
Field identification & locations
Easily identified by its translucent orange-red color, waxy luster, and conchoidal fracture. Commonly found in Brazil, India, Madagascar, and the United States.
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