sedimentary
Chert (with Limestone/Marble traces)
Silicon Dioxide (SiO2) / Microcrystalline Quartz
Hardness: 7 (Mohs scale); Color: Gray, tan, white with iron staining; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Gray, tan, white with iron staining
- Luster
- Waxy to dull
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: Gray, tan, white with iron staining; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains (diatoms, radiolarians) or chemical precipitation in marine environments; age varies from Precambrian to Cenozoic.
Uses & applications
Historically used for stone tools (flintknapping); currently used in road construction, landscape gravel, and as abrasive media.
Geological facts
Chert is so hard it can create sparks when struck against steel. It is one of the most durable rocks on the Earth's surface and often persists long after surrounding limestone has eroded.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its sharp, shell-like (conchoidal) edges when broken. Common in riverbeds and limestone outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary