sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, typically yellowish to brown exterior rind with a crystalline or sometimes hollow interior, vitreous luster when crystals are visible, conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, typically yellowish to brown exterior rind with a crystalline or sometimes hollow interior, vitreous luster when crystals are visible, conchoidal fracture.
Formation & geological history
Formed in hollow spaces in sedimentary or volcanic rocks, typically through the slow deposition of mineral-rich groundwater over millions of years.
Uses & applications
Popular in lapidary work, decorative objects, crystal healing, and mineral collections.
Geological facts
Geodes start as hollow bubbles in rock, often formed by animal burrows, tree roots, or gas bubbles in volcanic lava, which are gradually lined with mineral crystals.
Field identification & locations
Often found in limestone formations, deserts, and volcanic ash beds. Collectors frequently crack them open to reveal the crystalline interior.
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