sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture, and typically opaque with colors ranging from gray to brown.
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Physical properties
Hardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture, and typically opaque with colors ranging from gray to brown.
Formation & geological history
Formed through the chemical precipitation of silica from seawater or the accumulation of siliceous microfossil skeletons in marine environments.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; occasionally used for decorative landscaping and lapidary work.
Geological facts
Chert that is dark or black is frequently referred to as flint, and it has been utilized by humans for fire-starting and weaponry for hundreds of thousands of years.
Field identification & locations
Identified by its extreme hardness, smooth conchoidal breakage patterns, and waxy luster. Commonly found embedded in limestone and chalk formations worldwide.
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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
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Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary