sedimentary
Chert (Flint)
Microcrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, concoidal fracture, waxy to vitreous luster, various colors including yellow, brown, white, and gray.
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Physical properties
Hardness of 7 on the Mohs scale, concoidal fracture, waxy to vitreous luster, various colors including yellow, brown, white, and gray.
Formation & geological history
Formed in marine environments through the chemical precipitation of silica or replacement of limestone/chalk over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in aggregate, abrasives, and sometimes decorative items.
Geological facts
Chert and flint are essentially the same material, with 'flint' typically referring to varieties found in chalk formations and 'chert' in limestone.
Field identification & locations
Identified by its sharp, conchoidal fracture edges and extreme hardness which can scratch glass. Commonly found globally within sedimentary rock layers.
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