sedimentary
Flint / Chert
Silicon dioxide (SiO2) - Microcrystalline Quartz
Hardness: 7 on the Mohs scale, Color: Grey, black, brown, or white, Luster: Waxy to vitreous, Crystal structure: Microcrystalline/Cryptocrystalline, Cleavage: None (exhibits conchoidal fracture), Specific gravity: 2.60 to 2.65
Identified More sedimentary →
Explore Flint / Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on the Mohs scale, Color: Grey, black, brown, or white, Luster: Waxy to vitreous, Crystal structure: Microcrystalline/Cryptocrystalline, Cleavage: None (exhibits conchoidal fracture), Specific gravity: 2.60 to 2.65
Formation & geological history
Formed by the replacement of calcium carbonate by silica-rich solutions in marine environments (such as chalk or limestone formations) during the Cretaceous period or other sedimentary deposition eras.
Uses & applications
Historically used for making stone tools, arrowheads, and spark generation with steel; occasionally used in ornamental objects or abrasive media.
Geological facts
Flint was crucial for human survival during the Stone Age due to its ability to be chipped into extremely sharp edges through knapping and its capacity to strike sparks for fire.
Field identification & locations
Can be identified in the field by its distinct conchoidal fracture with razor-sharp edges, waxy luster, and high hardness capable of scratching glass.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary