sedimentary
Carnelian Agate
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
Hardness: 6.5-7 (Mohs scale); Color: Translucent orange-red to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Hexagonal (Microscopic); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Translucent orange-red to brownish-red
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Translucent orange-red to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Hexagonal (Microscopic); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.58-2.64
Formation & geological history
Formed in volcanic cavities or sedimentary environments where silica-rich fluids deposit layers of chalcedony. The reddish hue is caused by iron oxide (limonite or hematite) impurities trapped during formation.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and carvings. Historically used for signet rings and cylinders due to its ability to release wax cleanly.
Geological facts
Ancient Egyptians referred to carnelian as 'the setting sun.' It was thought to lend courage to the wearer and protect against the evil eye.
Field identification & locations
Identify in the field by its waxy texture and translucency when held to light. Common in riverbeds and gravel deposits, particularly in India, Brazil, and Uruguay.
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