sedimentary
Flint
Chert (Silicon dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: typically dark grey, black, or deep brown; Luster: waxy to glassy; Structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- typically dark grey, black, or deep brown
- Luster
- waxy to glassy
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: typically dark grey, black, or deep brown; Luster: waxy to glassy; Structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture.
Formation & geological history
Forms as nodules in sedimentary rocks like chalk or limestone through the replacement of calcium carbonate with silica from organic sources like sponges or diatoms.
Uses & applications
Historically used for stone tools and weapons (arrowheads); currently used in abrasives, ceramics, and as a lighter striker in survival gear.
Geological facts
Flint was the primary material for the Neolithic revolution, allowing humans to create sharp tools and start fires. It occurs globally, often found inside Cretaceous period chalk deposits.
Field identification & locations
Identify by its characteristic conchoidal fracture (smooth, curved breaks like glass) and its ability to create sparks when struck against steel. Commonly found in chalk shorelines and riverbeds.
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