sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on the Mohs scale, Color: various bands of white, grey, blue, red, green, and yellow, Luster: waxy to vitreous, Crystal structure: microcrystalline (trigonal), 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 bands of white, grey, blue, red, green, and yellow, Luster: waxy to vitreous, Crystal structure: microcrystalline (trigonal), Cleavage: none, Specific gravity: 2.58-2.64
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions in rhythmic layers over millions of years.
Uses & applications
Used for ornamental objects, jewelry, decorative carvings, and precision instruments such as mortar and pestles.
Geological facts
Agates are often named after the localities where they are found. The banding represents successive layers of solutions entering the cavity.
Field identification & locations
Identified by its characteristic concentric banding and waxy luster, frequently found in volcanic regions, riverbeds, and gravel deposits worldwide.
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