sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, earthy to vitreous luster, conchoidal fracture, and typically brown, gray, or white in color.
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Physical properties
Hardness of 7 on the Mohs scale, earthy to vitreous luster, conchoidal fracture, and typically brown, gray, or white in color.
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 by early humans for making stone tools and arrowheads due to its sharp conchoidal fracture, and occasionally used for decorative landscaping.
Geological facts
Chert that is dark or black is commonly known as flint. It has been utilized for thousands of years to create sparks for starting fires.
Field identification & locations
Identify in the field by its hardness, sharp edges when fractured, and smooth waxy luster. Commonly found within 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
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary