gemstone
Agate
Chalcedony (SiO2)
Hardness: 6.5-7 on the Mohs scale, Color: Various including brown, white, red, gray, blue, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline quartz), Cleavage: None, Specific Gravity: 2.58-2.64
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 on the Mohs scale, Color: Various including brown, white, red, gray, blue, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline quartz), Cleavage: None, Specific Gravity: 2.58-2.64
Formation & geological history
Formed in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, typically over millions of years.
Uses & applications
Used in jewelry, ornamental carvings, polished specimens, and industrial bearings or mortars.
Geological facts
Agate is a banded form of chalcedony and was named by Theophrastus, a Greek philosopher, after the Achates river in Sicily.
Field identification & locations
Identified by its characteristic concentric banding and waxy luster. Found worldwide, especially in volcanic regions.
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