sedimentary
Chert
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, earthy to waxy luster, conchoidal fracture, and colors ranging from white to brown and grey.
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Physical properties
Hardness of 7 on the Mohs scale, earthy to waxy luster, conchoidal fracture, and colors ranging from white to brown and grey.
Formation & geological history
Formed through the chemical precipitation of silica from aqueous solutions or the accumulation of siliceous microfossil skeletons in marine environments.
Uses & applications
Historically used for making stone tools and weapons due to its sharp edges when fractured.
Geological facts
Chert forms nodules or layers within sedimentary rock sequences like limestone and chalk over millions of years.
Field identification & locations
Identified by its extreme hardness, conchoidal fracture, and lack of reaction to acid. Commonly found in limestone formations worldwide.
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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
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Sandstone or Siltstone
Arenite (if sandstone)
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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)
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