sedimentary
Chert (Flint flake)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness 7 on Mohs scale, waxy to dull luster, conchoidal fracture, and a tan to dark grayish-brown color.
Identified More sedimentary →
Explore Chert (Flint flake) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 7 on Mohs scale, waxy to dull luster, conchoidal fracture, and a tan to dark grayish-brown color.
Formation & geological history
Formed by biochemical precipitation of silica from siliceous plankton skeletons or diagenetic replacement in limestone beds.
Uses & applications
Historically used for stone tools and fire-starting; currently utilized as road gravel and construction aggregate.
Geological facts
Because it breaks with razor-sharp conchoidal edges, chert was one of the most critical materials for prehistoric toolmakers.
Field identification & locations
Identified in the field by its extreme hardness (scratches glass), lack of cleavage, and smooth, curved shell-like fractures.
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