sedimentary
Flint / Chert with Fossils
Cryptocrystalline quartz (SiO2) with embedded fossil impressions
Hardness of 7 on the Mohs scale, colors range from grey and white to brown and black with waxy to vitreous luster, amorphous crystal structure (microcrystalline quartz), conchoidal fracture, specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from grey and white to brown and black with waxy to vitreous luster, amorphous crystal structure (microcrystalline quartz), conchoidal fracture, specific gravity around 2.60 to 2.65.
Formation & geological history
Formed through the replacement of calcium carbonate by silica in marine environments, often within chalk or limestone formations during the Cretaceous period and other geological eras.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used for decorative purposes, lapidary work, and gravel.
Geological facts
Flint is extremely durable and has been utilized by humans for hundreds of thousands of years due to its sharp conchoidal fracture edges when knapped.
Field identification & locations
Commonly found in chalk cliffs, riverbeds, and glacial tills worldwide; identified by its distinctive waxy luster, hardness capable of scratching glass, and conchoidal fracture.
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