sedimentary
Banded Chert (Flint)
Microcrystalline Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Cream, grey, and charcoal banding; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Cream, grey, and charcoal banding
- Luster
- Waxy to vitreous
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Cream, grey, and charcoal banding; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation in marine environments. This specimen shows typical water-worn rounding, likely from a riverbed or coastal area.
Uses & applications
Historically used for stone tools and weapons due to sharp edges; currently used for decorative stones, landscaping, and as a material for fire-starting (flint and steel).
Geological facts
Chert behaves like glass when broken, creating 'flakes' with edges sharper than a steel scalpel. It is one of the most common materials found at archaeological sites worldwide because of its durability.
Field identification & locations
Identify by its 'waxy' texture and curved, glass-like (conchoidal) fractures. It will easily scratch glass but cannot be scratched by a steel knife. Common in limestone regions and river gravels.
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