sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale. Color: Light grey to off-white/beige. Luster: Waxy to dull. Fracture: Distinct conchoidal fracture with sharp edges. Microcrystalline structure.
- Hardness
- 7 on Mohs scale
- Color
- Light grey to off-white/beige
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on Mohs scale. Color: Light grey to off-white/beige. Luster: Waxy to dull. Fracture: Distinct conchoidal fracture with sharp edges. Microcrystalline structure.
Formation & geological history
Formed biogenically or chemically through the precipitation of silica-rich fluids within marine sedimentary rocks, particularly limestones and chalk deposits.
Uses & applications
Historically used for stone tools, arrowheads, and flintlock firearms due to its sharp conchoidal fracture. Used today as road aggregate and ballast.
Geological facts
Because chert breaks with smooth, sharp edges like glass, it was one of the most critical materials used by early humans to manufacture knapped stone tools.
Field identification & locations
Identified by its high hardness (scratches steel), smooth waxy feel, and characteristic curved, shell-like conchoidal fracture surfaces. Extremely common in limestone terrains worldwide.
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