sedimentary
Quartz Geode
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectMohs hardness of 7, typically grey or brownish exterior with a crystalline quartz interior, vitreous luster.
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Physical properties
Mohs hardness of 7, typically grey or brownish exterior with a crystalline quartz interior, vitreous luster.
Formation & geological history
Formed in sedimentary or volcanic rock cavities where mineral-rich groundwater precipitated silica over millions of years.
Uses & applications
Commonly collected as mineral specimens, used in decorative items, or cut and polished for jewelry.
Geological facts
Geodes start as hollow bubbles in rock, often formed by animal burrows, tree roots, or gas pockets in lava.
Field identification & locations
Identify by its spherical, rough exterior and hollow, crystal-lined interior when broken open. Found globally in limestone and volcanic deposits.
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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
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
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Shale
Shale (clastic sedimentary rock)
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Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary