sedimentary
Chert
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and typically white, grey, brown, or black in color.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and typically white, grey, brown, or black in color.
Formation & geological history
Formed through the chemical precipitation of silica-rich fluids or accumulation of siliceous skeletal remains in marine environments over millions of years.
Uses & applications
Historically used for making stone tools and weapons due to its sharp edges when fractured; occasionally used in ornamental lapidary work.
Geological facts
Chert forms nodules or layers within sedimentary rock formations such as limestone and chalk. It is extremely durable and resists weathering.
Field identification & locations
Easily identified in the field by its conchoidal fracture, waxy luster, and high hardness that scratches glass. Found worldwide in sedimentary deposits.
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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