sedimentary
Chert (Fossiliferous Chert/Flint)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Gray to Tan, Luster: Waxy to dull, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Gray to Tan, Luster: Waxy to dull, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments, often replacing carbonate rocks. This specimen contains visible fossil inclusions, likely from the Paleozoic or Mesozoic eras.
Uses & applications
Historically used for stone tools and fire-starting. Currently used in road construction, landscaping, and as a decorative specimen for fossil collectors.
Geological facts
Chert is so hard it will scratch glass and even steel. It was highly prized by indigenous cultures for making arrowheads and scrapers due to its sharp, glass-like edges when broken.
Field identification & locations
Identify by its hardness (won't be scratched by a knife) and smooth, shell-like fracture surfaces. Often found in riverbeds or within limestone outcrops globally, especially in North America and Europe.
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