sedimentary
Banded Chert
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs), Color: Dark grey with brown/tan bands, Luster: Waxy to vitreous when polished, Crystal structure: Microcrystalline/cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
- Hardness
- 6
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs), Color: Dark grey with brown/tan bands, Luster: Waxy to vitreous when polished, Crystal structure: Microcrystalline/cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine or lacustrine environments; often found in Precambrian to Cenozoic strata.
Uses & applications
Used historically for stone tools and weapons due to its sharp edges; currently used for lapidary work, tumbling, and as decorative gravel.
Geological facts
Chert was a primary material for prehistoric hunter-gatherers to make arrowheads and scrapers. Flint is a common variety of dark chert.
Field identification & locations
Identify by its waxy luster, hardness (scratches glass), and the way it breaks into smooth, curved surfaces (conchoidal fracture). Commonly found in stream beds and coastal areas.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary