sedimentary
Chert (Flint)
Cryptocrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale); Color: Brown, tan, and grey; Luster: Waxy to dull; Crystal structure: Hexagonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Brown, tan, and grey
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Chert (Flint) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: Brown, tan, and grey; Luster: Waxy to dull; Crystal structure: Hexagonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed by the precipitation of microcrystalline silica from water, often as nodules or layers within limestone or chalk beds. This specimen likely dates from the Mesozoic or Cenozoic era.
Uses & applications
Historically used for stone tools (knapping) and fire-starting. Industrially used as an abrasive and in various construction aggregates. Popular among collectors as tumbling rough.
Geological facts
Flint is a specific variety of chert. When struck against steel, flint produces sparks, making it essential for ancient survival and early firearms (flintlocks).
Field identification & locations
Identifiable by its sharp, curved (conchoidal) edges and waxy texture. Commonly found in riverbeds, chalk cliffs, and fields over limestone bedrock.
More like this
Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary