sedimentary
Chert
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectMohs hardness of 7; waxy to dull luster; conchoidal fracture; tan to light brown color; opaque to translucent edges; no cleavage.
Identified More sedimentary →
Explore Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness of 7; waxy to dull luster; conchoidal fracture; tan to light brown color; opaque to translucent edges; no cleavage.
Formation & geological history
Formed primarily as a biological or chemical precipitate in marine environments where silica-rich fluids replace calcium carbonate or accumulate as radiolarian/diatomaceous ooze.
Uses & applications
Historically used for stone tools and fire-starting; currently used for road surfacing, decorative stone, and as a component in some ceramics.
Geological facts
Chert was the primary material for prehistoric arrowheads and scrapers due to its extreme hardness and the sharpness of its conchoidal fracture edges.
Field identification & locations
Identify by its waxy texture, inability to be scratched by a steel nail, and shell-like fracture patterns. Often found as nodules within limestone or chalk beds.
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