sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: tan, grey, or white with conchoidal (shell-like) fracture, Luster: dull to waxy, Crystal structure: microcrystalline quartz, Cleavage: none.
Identified More sedimentary →
Explore Chert (Flint) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: tan, grey, or white with conchoidal (shell-like) fracture, Luster: dull to waxy, Crystal structure: microcrystalline quartz, Cleavage: none.
Formation & geological history
Formed by the precipitation of silica in sedimentary environments, often within limestone or through the accumulation of siliceous microorganisms like diatoms or radiolarians.
Uses & applications
Historically used for stone tools and starting fires; currently used as construction aggregate, road surfacing, and in some decorative landscaping.
Geological facts
Chert was one of the most important materials for early humans because of its ability to break into extremely sharp edges. This specific specimen appears to be a weathered nodule.
Field identification & locations
Identify by its hardness (it can scratch glass and steel) and its smooth, curved fracture surfaces. Commonly found in riverbeds and limestone outcrops.
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