sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white and gray to brown and yellow due to impurities.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white and gray to brown and yellow due to impurities.
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 by early humans for making stone tools and arrowheads due to its sharp conchoidal fracture. Occasionally used in ornamental carvings.
Geological facts
Chert forms nodules or layers within sedimentary rocks like chalk and limestone. Flint is a well-known variety of dark chert.
Field identification & locations
Identified by its extreme hardness, smooth conchoidal fracture edges, and waxy luster. Commonly found worldwide in limestone formations.
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Other sedimentary specimens
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)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary