sedimentary
Chert (specifically Flint or Nodular Chert)
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Tan, beige, or cream; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal (shell-like curves)
- Hardness
- 7 on Mohs scale
- Color
- Tan, beige, or cream
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, beige, or cream; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal (shell-like curves)
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments, often as nodules within limestone or chalk beds.
Uses & applications
Historically used for stone tools (knapping) and fire-starting; currently used for decorative stone, landscaping, and as a raw material for ceramics and glass.
Geological facts
Chert breaks with a very sharp edge, which made it the primary material for arrowheads and spears for thousands of years. It is essentially a non-crystalline form of quartz.
Field identification & locations
Identify by its 'flinty' waxy surface and conchoidal fracture patterns. These specimens appear to be weathered nodules collected from a gravel pit or limestone deposit.
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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