sedimentary
Geode
Silicon dioxide (Quartz/Chalcedony nodule)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, spherical outer shell of chalcedony with a hollow crystalline interior, vitreous to dull luster.
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Physical properties
Hardness of 7 on the Mohs scale, spherical outer shell of chalcedony with a hollow crystalline interior, vitreous to dull luster.
Formation & geological history
Formed in sedimentary or volcanic rock cavities where mineral-rich groundwater deposits silica over millions of years.
Uses & applications
Popular in lapidary arts, jewelry making, ornamental displays, and mineral collecting.
Geological facts
Geodes often contain beautiful quartz or amethyst crystals inside despite their rough, unassuming exterior.
Field identification & locations
Identify in the field by their spherical, bumpy nodule shape that sounds hollow when tapped or is unusually lightweight.
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