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 dark gray or brown.
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Physical properties
Hardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and colors ranging from white to dark gray or brown.
Formation & geological history
Formed through the chemical precipitation of silica from aqueous solutions or the accumulation of siliceous microfossil skeletal remains in marine environments.
Uses & applications
Historically used for making stone tools, arrowheads, and spark-producing fire starters; currently used in abrasives and road aggregates.
Geological facts
Chert breaks with extremely sharp edges, making it a primary material for prehistoric humans to fashion cutting and hunting implements.
Field identification & locations
Identified by its distinctive conchoidal fracture, waxy luster, and ability to scratch glass easily; commonly found 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
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary