sedimentary
Flint / Chert
Microcrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, colors range from grey, brown, to black, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from grey, brown, to black, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity around 2.60 to 2.65.
Formation & geological history
Formed in marine environments as a chemical replacement of limestone or chalk by silica-rich solutions during the diagenesis of sedimentary strata.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in abrasives, decorative landscaping, and occasionally lapidary art.
Geological facts
Flint was one of the earliest materials manipulated by early humans to create sharp cutting edges and weapons due to its predictable conchoidal fracture.
Field identification & locations
Can be identified by its conchoidal fracture pattern and hardness that easily scratches glass; commonly found embedded in chalk and limestone deposits worldwide.
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