sedimentary
Flint
Sedimentary cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness 7 on the Mohs scale, waxy luster, conchoidal fracture, and typically dark gray to black or brown with white weathering rinds.
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Physical properties
Hardness 7 on the Mohs scale, waxy luster, conchoidal fracture, and typically dark gray to black or brown with white weathering rinds.
Formation & geological history
Formed through the chemical replacement of calcium carbonate in chalk or limestone by silica-rich solutions during the Cretaceous period.
Uses & applications
Historically used for making stone tools and fire-starting flintlocks; currently utilized in abrasives and decorative landscaping.
Geological facts
Prehistoric humans heavily favored flint for knapping sharp blades and arrowheads due to its predictable conchoidal fracture.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster, and conchoidal breakage pattern; commonly found embedded in chalk cliffs worldwide.
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