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 microfossils in marine environments.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp edges when fractured.
Geological facts
Chert forms nodules or layers within sedimentary rocks like limestone and chalk.
Field identification & locations
Identified easily by its extreme hardness, smooth conchoidal fracture, and waxy sheen; found globally in sedimentary strata.
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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)
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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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