sedimentary
Flint
Cryptocrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, typically dark gray, black, or brown with a waxy to vitreous luster and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark gray, black, or brown with a waxy to vitreous luster and conchoidal fracture.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich solutions in marine environments over millions of years.
Uses & applications
Historically used for making stone tools and striking fire; currently used in decorative aggregates, ceramics, and abrasives.
Geological facts
Flint is extremely durable and breaks with very sharp edges, making it one of the most important materials for early human technology.
Field identification & locations
Found worldwide within chalk and limestone formations; identifiable by its conchoidal fracture, waxy luster, and ability to spark when struck with steel.
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