sedimentary
Flint
Sedimentary cryptocrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, dark gray to black color, waxy to vitreous luster, conchoidal fracture, and amorphous/microcrystalline crystal structure.
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Physical properties
Hardness of 7 on the Mohs scale, dark gray to black color, waxy to vitreous luster, conchoidal fracture, and amorphous/microcrystalline crystal structure.
Formation & geological history
Formed by the replacement of calcium carbonate by silica in chalk or limestone beds during the Cretaceous period through diagenesis.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in specialized grinding and abrasives.
Geological facts
Flint is extremely durable and produces sharp edges when fractured, making it one of the earliest materials utilized by human ancestors for primitive technology.
Field identification & locations
Easily identified by its conchoidal fracture, sharp edges, and hardness capable of scratching glass. Commonly found within chalk formations across northern Europe.
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