sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, translucent to opaque transparency, microcrystalline quartz structure with distinctive banding or patterns, and a specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, translucent to opaque transparency, microcrystalline quartz structure with distinctive banding or patterns, and a specific gravity of 2.58 to 2.64.
Formation & geological history
Formed primarily within the cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Widely used for tumbled stones, ornamental carvings, jewelry, and polished specimens for collectors.
Geological facts
Agate was named by the Greek philosopher Theophrastus after the Achates river in Sicily, where the stones were found in ancient times.
Field identification & locations
Easily identified by its characteristic concentric bands or translucent appearance; commonly found in volcanic regions worldwide.
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