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 remains in marine environments.
Uses & applications
Historically used for making stone tools and weapons due to its sharp conchoidal fracture; occasionally used in decorative landscaping.
Geological facts
Chert that is dark or black is commonly referred to as flint. It is extremely durable and resistant to weathering.
Field identification & locations
Identify in the field by its hard conchoidal fracture and lack of reaction to acid. Commonly found within limestone and chalk deposits 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
fossil
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)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary