sedimentary
Chert (Flint)
Chert (SiO2)
Hardness: 7 (Mohs scale); Color: Gray, black, brown, or tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Gray, black, brown, or tan
- 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, black, brown, or tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (microscopic quartz); 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 (arrowheads). Modern uses include road construction aggregate, fire-starting flint, and occasionally as semi-precious gemstones (jaspers).
Geological facts
Flint is a variety of chert that was essential to human survival in the Stone Age due to its ability to produce a sharp edge when fractured and create sparks when struck against steel.
Field identification & locations
Identified in the field by its smooth, waxy surface and distinctive shell-like (conchoidal) fracture patterns. Look for it in sedimentary outcrops or as rounded pebbles in stream beds.
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
Arenite
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary