sedimentary
Geode
Quartz / Chalcedony (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, vitreous to dull luster, cryptocrystalline or microcrystalline structure, and white to bluish-gray interior crystals.
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Physical properties
Hardness of 7 on the Mohs scale, vitreous to dull luster, cryptocrystalline or microcrystalline structure, and white to bluish-gray interior crystals.
Formation & geological history
Formed in sedimentary or volcanic rock cavities where mineral-rich groundwater precipitated silica over millions of years.
Uses & applications
Used primarily as decorative specimens, in lapidary arts, and for crystal collections.
Geological facts
Geodes start as hollow bubbles in rock, often formed by animal burrows, tree roots, or gas bubbles in volcanic lava.
Field identification & locations
Identified by a roughly spherical, bumpy exterior and a hollow interior lined with sparkling crystals; found globally in limestone and volcanic formations.
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