sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and colors ranging from white to gray and dark blue-grey.
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Physical properties
Hardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and colors ranging from white to gray and dark blue-grey.
Formation & geological history
Formed through the chemical precipitation of silica from seawater or the accumulation of siliceous microfossil skeletons over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; currently used for abrasive grinding and landscaping.
Geological facts
Chert often occurs as nodules or concretions inside limestone and chalk formations and was a primary material for prehistoric weaponry.
Field identification & locations
Identify in the field by its distinct waxy luster, extreme hardness that scratches glass, and sharp, curved fracture edges. Found worldwide in sedimentary strata.
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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