sedimentary
Agate Nodule
Silicon dioxide (chalcedony, SiO2)
AI-generated identification · may be incorrectHardness 6.5-7 on the Mohs scale, waxy luster, conchoidal fracture, and microscopic fibrous crystal structure.
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Physical properties
Hardness 6.5-7 on the Mohs scale, waxy luster, conchoidal fracture, and microscopic fibrous crystal structure.
Formation & geological history
Formed in cavities of volcanic or sedimentary rocks through the deposition of silica-rich groundwater over millions of years.
Uses & applications
Used primarily in lapidary arts, ornamental carvings, polished display specimens, and gemstone jewelry.
Geological facts
Agate banding reflects successive pulses of mineral-rich fluid entering cavities. Ancient civilizations valued it for talismans and seals.
Field identification & locations
Identify by characteristic concentric color bands, waxy luster, and high hardness scratching glass. Found worldwide in volcanic regions.
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