sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white to gray, brown, or red.
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Physical properties
Hardness of 7 on Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white to gray, brown, or red.
Formation & geological history
Formed through the chemical precipitation of silica from aqueous solutions or the accumulation of siliceous skeletal remains of marine organisms over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; occasionally used in decorative landscaping and lapidary work.
Geological facts
Chert forms nodules or layers within sedimentary rocks like limestone and chalk, and varieties include flint, jasper, and agate.
Field identification & locations
Identify in the field by its extreme hardness, waxy luster, and distinctive sharp-edged conchoidal breakage; found globally in limestone formations.
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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