sedimentary
Agate
Silicon dioxide, SiO2 (Chalcedony variety)
AI-generated identification · may be incorrectHardness 6.5-7 on Mohs scale; translucent to opaque; waxy to vitreous luster; cryptocrystalline quartz structure with conchoidal fracture.
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Physical properties
Hardness 6.5-7 on Mohs scale; translucent to opaque; waxy to vitreous luster; cryptocrystalline quartz structure with conchoidal fracture.
Formation & geological history
Forms primarily within cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater over millions of years.
Uses & applications
Widely used in ornamental carvings, jewelry, tumbled stones, and precision instruments.
Geological facts
Agate banding represents successive layers of microscopic quartz crystals settling from silica solutions in ancient cavities.
Field identification & locations
Easily identified by concentric color bands, waxy luster, and resistance to steel scratching; common in riverbeds and volcanic regions worldwide.
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