Sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness 6.5-7 on Mohs scale, typically occurs in massive form. Conchoidal fracture. Color can vary widely; this piece shows tan, light brown, and gray hues. Waxy to dull luster.
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 6.5-7 on Mohs scale, typically occurs in massive form. Conchoidal fracture. Color can vary widely; this piece shows tan, light brown, and gray hues. Waxy to dull luster.
Formation & geological history
Formed as a chemical sedimentary rock, typically from the precipitation of silica from groundwater or oceanic water, often replacing other minerals or organic material.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its conchoidal fracture. Sometimes used as a low-grade road material or collected as a specimen.
Geological facts
Flint is a type of chert that occurs specifically in chalk or marly limestone deposits. The sharp edges produced when fractured made it invaluable to early humans.
Field identification & locations
Identified by its waxy luster, hardness (scratches glass), and conchoidal fracture. Often found as nodules in limestone or as layered deposits. Look for smooth, curved broken surfaces.
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