sedimentary
Black Chert River Stone
Cryptocrystalline Quartz (SiO2)
Hardness: 7 Mohs scale. Color: Dark grey to black with light banding. Luster: Waxy to dull. Crystal structure: Microcrystalline. Specific gravity: 2.6-2.7. Very smooth due to water erosion.
- Hardness
- 7 Mohs scale
- Color
- Dark grey to black with light banding
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Black Chert River Stone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 Mohs scale. Color: Dark grey to black with light banding. Luster: Waxy to dull. Crystal structure: Microcrystalline. Specific gravity: 2.6-2.7. Very smooth due to water erosion.
Formation & geological history
Formed in marine environments as chemical precipitates or through the replacement of limestone. This specific specimen has been polished smooth by river or beach water action.
Uses & applications
Commonly used as decorative landscaping stones, aquarium gravel, and historically for stone tools (flint). Tumbled versions are used in meditation and pocket charms.
Geological facts
Chert has a conchoidal fracture, which means it breaks like glass. This property made it essential for prehistoric humans to create sharp-edged tools like arrowheads.
Field identification & locations
Identified by its hardness (cannot be scratched by steel), waxy texture, and smooth rounded shape. Found globally in riverbeds and coastal regions.
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