sedimentary
Flint / Chert
Microcrystalline Quartz (SiO2)
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, opaque to translucent, colors commonly grey, dark grey, white, or yellowish due to impurities.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, opaque to translucent, colors commonly grey, dark grey, white, or yellowish due to impurities.
Formation & geological history
Formed through the replacement of calcium carbonate by silica-rich solutions in marine environments (such as chalk or limestone formations) over millions of years.
Uses & applications
Historically used for making stone tools, weapons, and fire-starting. Today used in decorative landscaping, abrasives, and by historical reenactors.
Geological facts
Flint was one of the earliest materials manipulated by early humans to create sharp cutting edges and arrowheads due to its predictable conchoidal fracture.
Field identification & locations
Can be identified in the field by its distinctive smooth, water-worn exterior (if a pebble), conchoidal fracture showing sharp edges when broken, and high hardness capable of scratching glass.
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