sedimentary
Flint / Chert (Beach-worn Pebble)
Microcrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture, smooth water-worn surface with characteristic dark and amber-brown coloration.
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Physical properties
Hardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture, smooth water-worn surface with characteristic dark and amber-brown coloration.
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 and fire-starting (flint and steel); currently used as decorative beach stones or collected as a specimen.
Geological facts
Flint and chert are types of quartz that break with a sharp, conchoidal fracture, making them historically invaluable for early human toolmaking.
Field identification & locations
Found worldwide in chalk and limestone formations, frequently discovered as smooth pebbles along beaches and riverbeds where wave action has eroded the nodule.
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