sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on Mohs scale, colors range from white to black with waxy to vitreous luster, conchoidal fracture with no true cleavage.
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Physical properties
Hardness of 7 on Mohs scale, colors range from white to black with waxy to vitreous luster, conchoidal fracture with no true cleavage.
Formation & geological history
Formed via the accumulation of siliceous microfossil skeletal remains or chemical precipitation in marine environments over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; occasionally used for decorative landscaping and tumbling.
Geological facts
Ancient humans prized chert and flint for fire-starting when struck against steel, producing hot sparks.
Field identification & locations
Easily identified in the field by its extreme hardness, waxy luster, and distinctive sharp, curved conchoidal breakage patterns.
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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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