sedimentary
Flint
SiO2
AI-generated identification · may be incorrectMohs hardness 7, waxy to vitreous luster, conchoidal fracture, cryptocrystalline quartz structure, typically gray to dark brown or black.
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Physical properties
Mohs hardness 7, waxy to vitreous luster, conchoidal fracture, cryptocrystalline quartz structure, typically gray to dark brown or black.
Formation & geological history
Formed through the chemical replacement of calcium carbonate in limestone or chalk by silica-rich solutions during the Cenozoic and Mesozoic eras.
Uses & applications
Historically used for making sharp tools, weapons, and fire-starting flintlocks; modern uses include landscaping and decorative aggregate.
Geological facts
Flint fractures with extremely sharp edges known as conchoidal fractures, making it the premier material for primitive stone-tool knapping.
Field identification & locations
Identify by its waxy luster, conchoidal fracture, and ability to spark when struck with steel; commonly found as nodules within chalk and limestone formations.
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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