sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, typically yellowish to brown outer rind with internal clear or amber quartz crystals, vitreous luster, hexagonal crystal system, no cleavage, specific gravity of 2.65
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Physical properties
Hardness of 7 on the Mohs scale, typically yellowish to brown outer rind with internal clear or amber quartz crystals, vitreous luster, hexagonal crystal system, no cleavage, specific gravity of 2.65
Formation & geological history
Formed in hollow spaces in sedimentary or volcanic rocks, where silica-rich groundwater gradually precipitates quartz crystals over millions of years
Uses & applications
Used as decorative specimens, crystal healing, and in jewelry or lapidary arts
Geological facts
Geodes start as hollow nodules or cavities in rock, often formed from animal burrows, tree roots, or gas bubbles in volcanic lava, which are slowly lined with mineral crystals
Field identification & locations
Can be identified in the field by looking for distinctive round or oval nodule shapes that feel unusually heavy and hollow when cracked open; commonly found in limestone formations
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