mineral
Carnelian Agate
Silicon Dioxide (SiO2) - variety of Chalcedony
Hardness: 6.5-7.0 (Mohs scale), Color: Orange to reddish-brown, Luster: Vitreous to waxy, Crystal Structure: Trigonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64
- Hardness
- 6
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Physical properties
Hardness: 6.5-7.0 (Mohs scale), Color: Orange to reddish-brown, Luster: Vitreous to waxy, Crystal Structure: Trigonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64
Formation & geological history
Formed through the deposition of silica-rich groundwater in volcanic rock cavities or sedimentary environments. The orange hue is caused by iron oxide impurities.
Uses & applications
Primarily used as a semi-precious gemstone in jewelry (cabochons, beads), decorative carvings, signet rings, and as a collector's specimen.
Geological facts
Carnelian has been used since the Neolithic period; it was highly prized by the Ancient Egyptians for amulets and the Romans for signet rings because hot wax does not stick to it.
Field identification & locations
Identify by its translucent waxy luster and distinctive conchoidal (shell-like) fracture. Commonly found in riverbeds or gravel deposits in Brazil, India, and the Pacific Northwest of the USA.
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