sedimentary
Chert (or Flint)
Chert (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs), Color: Tan, brown, or grey, Luster: Waxy to dull, Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal
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Physical properties
Hardness: 7 (Mohs), Color: Tan, brown, or grey, Luster: Waxy to dull, Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation in sedimentary basins as nodules or beds.
Uses & applications
Historically used for stone tools and fire-starting; currently used for road base, decorative landscaping, and occasionally jewelry.
Geological facts
Flint is a variety of chert that was the primary material for prehistoric arrowheads and spear points due to its sharp, predictable fracture edges.
Field identification & locations
Identify by its extreme hardness (scratches glass) and shell-like (conchoidal) fracture patterns. Found globally in limestone and chalk deposits.
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Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
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Sandstone or Siltstone
Arenite (if sandstone)
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Sandstone
Arenite
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Shale
Shale (clastic sedimentary rock)
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Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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