sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectMohs hardness of 7, vitreous to dull luster, conchoidal fracture, and compact microcrystalline structure ranging in color from white to brown and grey.
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Physical properties
Mohs hardness of 7, vitreous to dull luster, conchoidal fracture, and compact microcrystalline structure ranging in color from white to brown and grey.
Formation & geological history
Formed through the chemical precipitation of silica-rich fluids or accumulation of siliceous microfossils in marine environments over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; currently used in landscaping and abrasives.
Geological facts
Chert weathering often creates a chalky outer rind known as cortex. Flint is a well-known dark variety of chert.
Field identification & locations
Identified by its extreme hardness, waxy luster, and sharp conchoidal fracture. 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