sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Tan, brown, or grey; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or grey
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or grey; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or by chemical precipitation in marine or groundwater environments.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) and starting fires. Today used as road surfacing material or for decorative landscaping.
Geological facts
Flint is a variety of chert that was essential to human survival for thousands of years due to its ability to produce sharp edges and create sparks when struck against steel.
Field identification & locations
Identify by its 'shell-like' conchoidal fracture patterns and extreme hardness (it will scratch glass). Often found as nodules within limestone or chalk beds.
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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