sedimentary
Chert (often called Flint)
Chert (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: tan, grey, white, buff with iron staining, Luster: dull to waxy, Structure: microcrystalline quartz, Cleavage: none (conchoidal fracture), Specific Gravity: 2.65
Identified More sedimentary →
Explore Chert (often called 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, white, buff with iron staining, Luster: dull to waxy, Structure: microcrystalline quartz, Cleavage: none (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation within limestone/chalk beds; often found as nodules or bedded deposits.
Uses & applications
Historical tool making (arrowheads/knives), construction aggregate, road stone, and occasionally used as a strike-stone for fire-starting.
Geological facts
Chert breaks with a conchoidal fracture, creating extremely sharp edges that were essential to prehistoric tool technology. It is chemically identical to quartz but has a different microscopic structure.
Field identification & locations
Identify in the field by its hardness (it will scratch glass), its smooth waxy feel, and the distinctive curved, shell-like sharp fractures where it has been chipped.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary