mineral
Carnelian
Silicon Dioxide (Chalcedony variety), SiO2
Hardness of 6.5 to 7 on the Mohs scale, orange to brownish-red color, vitreous to waxy luster, microcrystalline (cryptocrystalline) crystal structure, conchoidal fracture with no true cleavage, 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 brownish-red color, vitreous to waxy luster, microcrystalline (cryptocrystalline) crystal structure, conchoidal fracture with no true cleavage, specific gravity around 2.58 to 2.64.
Formation & geological history
Forms in low-temperature hydrothermal environments, groundwater solutions depositing silica in cavities of volcanic and sedimentary rocks, often associated with ancient volcanic activity.
Uses & applications
Used widely in jewelry, signet rings, beads, carvings, and as a semi-precious gemstone.
Geological facts
Carnelian has been prized since ancient times, frequently used in ancient Egypt, Rome, and Greece for intaglio seals and talismans due to its ability to prevent wax from sticking to the signet.
Field identification & locations
Can be identified in the field by its waxy luster, translucent orange-to-red coloration, and smooth conchoidal fracture. Common localities include India, Brazil, Uruguay, and the United States.
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