sedimentary
Agate Geode
Silicon dioxide (Chalcedony/Quartz), SiO2
AI-generated identification · may be incorrectHardness of 6.5-7 on the Mohs scale, waxy to vitreous luster, banded color patterns ranging from brown to white with a crystalline quartz core, and trigonal crystal system.
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Physical properties
Hardness of 6.5-7 on the Mohs scale, waxy to vitreous luster, banded color patterns ranging from brown to white with a crystalline quartz core, and trigonal crystal system.
Formation & geological history
Formed through the deposition of silica-rich groundwater inside gas cavities in volcanic or sedimentary rocks over millions of years.
Uses & applications
Widely used in ornamental carvings, gemstone jewelry, decorative display pieces, and industrial abrasive bearings.
Geological facts
Geodes form when mineral-rich fluids seep into hollow cavities and slowly crystallize layer by layer from the outside inward, often leaving a hollow quartz-lined center.
Field identification & locations
Easily identified by distinctive concentric color bands surrounding a crystal-lined cavity; found globally in volcanic rock formations and river gravels.
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