sedimentary
Chert (with nodule)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: tan, cream, with dark brown inclusion; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 6
- Color
- tan, cream, with dark brown inclusion
- Luster
- waxy to dull
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs scale); Color: tan, cream, with dark brown inclusion; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments; often found as nodules in limestone or chalk beds.
Uses & applications
Historically used for stone tools and weapons due to its sharp edges; currently used for road surfacing, gravel, and occasionally as lapidary material for hobbyists.
Geological facts
Chert was one of the most important materials for early humans; its ability to produce a razor-sharp edge when fractured made it essential for survival. Flint is a variety of chert.
Field identification & locations
Identify by its waxy luster, extreme hardness (it will scratch glass), and smooth, curved conchoidal fractures. Common in riverbeds and limestone outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary