sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and colors ranging from white to brown and black.
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Physical properties
Hardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and colors ranging from white to brown and black.
Formation & geological history
Formed through the chemical precipitation of silica-rich fluids or accumulation of siliceous microfossils within sedimentary basins.
Uses & applications
Historically used for making stone tools and weapons due to its sharp conchoidal fracture. Also used for decorative landscaping and occasionally lapidary work.
Geological facts
Chert forms nodules or beds within limestone and chalk formations. Varieties like flint have been utilized by humans for over two million years.
Field identification & locations
Identify in the field by its extreme hardness, conchoidal fracture, and smooth nodular outer cortex. Found worldwide in sedimentary rock sequences.
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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)
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