mineral
Carnelian Agate / Chalcedony
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5-7 on Mohs scale; Color: Orange-brown, translucent to semi-translucent; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Orange-brown, translucent to semi-translucent
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Orange-brown, translucent to semi-translucent; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64
Formation & geological history
Formed by the precipitation of silica-rich fluids in cavities within volcanic or sedimentary rocks, often developing botryoidal textures and faint color zoning as iron impurities leach in.
Uses & applications
Widely used for lapidary arts, jewelry (cabochons, beads), decorative carvings, and mineral collections.
Geological facts
Carnelian has been used in jewelry making for over 4,500 years, notably in ancient Egyptian, Roman, and Sumerian cultures for seals and amulets.
Field identification & locations
Identified by its waxy luster, smooth conchoidal fracture surfaces, botryoidal growth patterns, and translucent orange-brown color. Commonly found in basaltic decay zones, gravels, and riverbeds in Brazil, India, Madagascar, and parts of Africa.
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