mineral
Carnelian
Carnelian (Silica/Quartz Variety), SiO2 with Fe2O3 impurities
Hardness: 6.5-7 (Mohs); Color: Orange, reddish-brown, or translucent red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Orange, reddish-brown, or translucent red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Orange, reddish-brown, or translucent red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Formed primarily in volcanic environments where silica-rich groundwater percolates through cavities in igneous rock, precipitating chalcedony at low temperatures over millions of years. The color is derived from iron oxide impurities.
Uses & applications
Extensively used in lapidary work for cabochons, beads, intaglios, and jewelry. Historically used for signet rings and wax seals due to its waxy luster which prevents hot wax from sticking.
Geological facts
Ancient Egyptians called carnelian "the setting sun" and believed it could protect the soul in the afterlife. It was also used by Roman and Greek civilizations for engraving seals and amulets.
Field identification & locations
Identify by its translucent, waxy appearance and orange-red hue. Commonly found in Brazil, India, Madagascar, and Uruguay. In the field, look for nodules with a smooth, conchoidal fracture.
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