mineral
Carnelian
Carnelian (Cryptocrystalline Quartz, SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Orange to reddish-brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Orange to reddish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Orange to reddish-brown; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
Formation & geological history
Forms primarily as a secondary mineral in volcanic rock cavities or sedimentary environments through the deposition of silica from groundwater. The orange-red color comes from impurities of iron oxide (hematite).
Uses & applications
Widely used for jewelry (beads, cabochons, rings), seal stones, carvings, and as a popular tumbled stone for collectors.
Geological facts
Ancient Romans used carnelian for signet rings because hot wax does not stick to it. It has been used in jewelry for over 4,500 years, dating back to Ur and ancient Egypt.
Field identification & locations
Identify by its translucent, waxy finish and even orange-to-red color. It can be found in India, Brazil, Uruguay, and Madagascar. Collectors often look for uniform color and transparency.
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