sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure (microscopic quartz fibers), conchoidal fracture, specific gravity of 2.58 to 2.64, typically exhibits multicolored concentric banding.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure (microscopic quartz fibers), conchoidal fracture, specific gravity of 2.58 to 2.64, typically exhibits multicolored concentric banding.
Formation & geological history
Formed primarily within the cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Commonly used in jewelry, decorative carvings, ornamental objects, and industrial bearings or mortars.
Geological facts
Agates were named by the ancient Greek philosopher Theophrastus after the Achates river in Sicily where he found the stones.
Field identification & locations
Can be identified in the field by its waxy luster, translucent edges, and distinct banded patterns, frequently found in riverbeds, glacial tills, and volcanic regions worldwide.
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