sedimentary
Flint (Chert variant)
Microcrystalline Quartz (SiO2)
Mohs hardness 7, dark gray to black core with lighter beige/brown weathered rind (cortex), subvitreous to waxy luster, conchoidal fracture with sharp edges, dense with no cleavage.
Identified More sedimentary →
Explore Flint (Chert variant) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness 7, dark gray to black core with lighter beige/brown weathered rind (cortex), subvitreous to waxy luster, conchoidal fracture with sharp edges, dense with no cleavage.
Formation & geological history
Formed during the Cretaceous period in marine sedimentary environments, specifically within chalk and limestone formations through the precipitation of silica from ancient sponge spicules and radiolarians.
Uses & applications
Historically used for stone tools, arrowheads, and spark-striking flints. Modern uses include aggregate material, decorative landscaping, and educational geology samples.
Geological facts
Flint was one of the most critical materials for prehistoric humans due to its ability to break with sharp, glass-like edges (conchoidal fracture) and produce sparks when struck against iron or pyrite.
Field identification & locations
Extremely common in northern Germany (Lower Saxony region around 53.5°N, 8.6°E) as glacial erratic deposits transport chalk-derived flint nodules across the northern plains. Look for dark gray silicate interiors encased in a chalky, pale exterior rind.
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
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale
Sedimentary Shale
sedimentary
Shale and Pebble Fragment
Sedimentary Rock (Mudstone/Shale with Silica Pebble)
sedimentary