sedimentary
Banded Chert
Chert (Microcrystalline Quartz, SiO2)
Hardness: 7 on Mohs scale; Color: Tan, beige, grey, and brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Cleavage: None
- Hardness
- 7 on Mohs scale
- Color
- Tan, beige, grey, and brown
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Banded Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Tan, beige, grey, and brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Cleavage: None
Formation & geological history
Formed by the accumulation and lithification of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation from hydrothermal fluids in marine environments. Often found as nodules or layers within limestone.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to conchoidal fracture. Currently used as road surfacing material, in construction, and as decorative landscape stones.
Geological facts
Chert is so hard it can scratch steel and was used for centuries as a 'flint' to start fires. The banding represents changes in sediment deposition or mineral impurities over time.
Field identification & locations
Identify in the field by its waxy texture and sharp, shell-like (conchoidal) fracture patterns when broken. Common in limestone belts and riverbeds in the Midwestern USA and Europe.
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
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary