sedimentary
Chert (Flint variety)
Silicon dioxide (SiO2)
Hardness: 7 Mohs; Color: Gray, tan, and dark brown; Luster: Waxy to dull; Structure: Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 Mohs
- Color
- Gray, tan, and dark brown
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Chert (Flint variety) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 Mohs; Color: Gray, tan, and dark brown; Luster: Waxy to dull; Structure: Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of siliceous remains of marine organisms or chemical precipitation of silica-rich fluids within limestone or chalk beds. Often found in nodules.
Uses & applications
Historically used for stone tools/weapons; currently used in construction aggregate, road surfacing, and as a starting stone for fire-making.
Geological facts
Chert is so hard it can scratch steel and was the primary material for arrowheads and scrapers in prehistoric times due to its sharp, glass-like edges when broken.
Field identification & locations
Identify by its waxy appearance and conchoidal (shell-like) fracture pattern. Commonly found in riverbeds and limestone outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
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 (primarily SiO2)
sedimentary