sedimentary
Chert (Flint)
Chert (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: tan/beige/gray, Luster: waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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/beige/gray, Luster: waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like radiolarians or diatoms) or by chemical precipitation in marine environments. Typically found as nodules in limestone or chalk beds.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its sharp edges; used today as road gravel, in ceramics, and occasionally as an abrasive.
Geological facts
Chert is so hard it can scratch steel. When struck against steel, it produce sparks, making it a primary material for flintlock firearms and fire-starting throughout history.
Field identification & locations
Identify in the field by its very smooth, waxy surface and shell-like (conchoidal) fractures. It is commonly found in gravel pits, riverbeds, or embedded in limestone outcrops.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary