sedimentary
Flint / Chert
Cryptocrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, typically dark brown to black or gray in color, waxy to vitreous luster, conchoidal fracture, and amorphous crystal structure.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark brown to black or gray in color, waxy to vitreous luster, conchoidal fracture, and amorphous crystal structure.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich solutions or the accumulation of siliceous skeletal remains of marine organisms over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used for decorative landscaping, road construction, and grinding mills.
Geological facts
Flint was one of the earliest materials manipulated by prehistoric humans to create sharp cutting edges and weapons due to its predictable conchoidal fracture.
Field identification & locations
Can be identified by its distinctive conchoidal fracture (curved, shell-like breaking pattern), waxy luster, and ability to spark when struck against steel.
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