sedimentary
Quartz Geode
Quartz (Silicon Dioxide, SiO2) in a Geode
Hardness: 7 (Mohs scale), Color: Clear to milky crystals in a brown/grey host rock, Luster: Vitreous/glassy crystals, Crystal Structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Clear to milky crystals in a brown/grey host rock, Luster: Vitreous/glassy crystals, Crystal Structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed as hollow cavities in sedimentary or volcanic rock that are filled by the slow precipitation of mineral-rich water over millions of years.
Uses & applications
Commonly used for geological study, home decor, metaphysical collecting, and occasionally as a source for small gemstones.
Geological facts
The word geode is derived from the Greek word Geoides, which means earth-like. Unlike vugs, geodes have a hollow interior lined with crystals.
Field identification & locations
Identify in the field by looking for round, bumpy, cauliflower-like nodules that feel lighter than solid rocks of the same size. Commonly found in deserts or river beds.
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