sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness of 7 on Mohs scale, white to clear crystal interior with brownish limestone outer shell, vitreous luster, trigonal crystal system.
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Physical properties
Hardness of 7 on Mohs scale, white to clear crystal interior with brownish limestone outer shell, vitreous luster, trigonal crystal system.
Formation & geological history
Formed in hollow cavities of sedimentary or volcanic rocks where silica-rich groundwater precipitated quartz crystals over millions of years.
Uses & applications
Commonly used in decorative items, lapidary arts, jewelry, and as popular specimens for mineral collectors.
Geological facts
Geodes start as empty bubbles in rock, often formed from animal burrows, tree roots, or gas pockets in lava, and slowly line themselves with crystals.
Field identification & locations
Easily identified by cracking open unassuming, round, bumpy rocks to reveal sparkling crystal interiors; widely found in deserts and limestone formations.
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Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary