sedimentary
Chert
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white to dark brown.
Identified More sedimentary →
Explore Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and colors ranging from white to dark brown.
Formation & geological history
Formed via the chemical precipitation of silica from seawater or the replacement of limestone by silica-rich solutions over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp conchoidal fracture; occasionally used in landscaping or decorative gravel.
Geological facts
Chert is extremely durable and weather-resistant, often surviving in the geological record long after surrounding limestone dissolves.
Field identification & locations
Identify by its dense microcrystalline structure, hardness, and signature conchoidal fracture. Commonly found in limestone and chalk formations worldwide.
More like this
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