sedimentary
Chert (Flint variety)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs scale), Color: Dark brown to black, Luster: Waxy to vitreous, Crystal structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
- Hardness
- 6
Identified More sedimentary →
Explore Chert (Flint variety) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Dark brown to black, Luster: Waxy to vitreous, Crystal structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed by the accumulation of siliceous remains of organisms or chemical precipitation from silica-rich groundwater within sedimentary beds.
Uses & applications
Used historically for stone tools and fire-starting; currently used in construction aggregates and occasionally as a laboratory abrasive.
Geological facts
Because of its conchoidal fracture, it was the primary material for spearheads and arrowheads during the Stone Age. It produces sparks when struck against steel.
Field identification & locations
Look for a smooth, waxy texture and sharp, shell-like (conchoidal) edges where broken. Commonly found in limestone and chalk deposits.
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