mineral
Carnelian (Chalcedony)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5 - 7 on Mohs scale; Color: Orange, reddish-brown, yellow-orange; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.58 - 2.64.
- Hardness
- 6
- Color
- Orange, reddish-brown, yellow-orange
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5 - 7 on Mohs scale; Color: Orange, reddish-brown, yellow-orange; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.58 - 2.64.
Formation & geological history
Forms in low-temperature hydrothermal environments, volcanic rocks, and gas cavities (geodes) when silica-rich fluids deposit in rock crevices, gaining its reddish-orange tone from iron oxide impurities.
Uses & applications
Used widely in jewelry (beads, cabochons, carved rings), lapidary art, and as a popular collectible gemstone.
Geological facts
Carnelian has been used for ornamentation for over 4,500 years. Ancient Romans used carnelian signet rings to seal official documents because hot wax does not stick to it.
Field identification & locations
Look for a translucent to semi-translucent reddish-orange color with a characteristic waxy surface texture and smooth conchoidal fractures. Commonly found in India, Brazil, Madagascar, and parts of the USA.
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