sedimentary
Chert / Flint
Microcrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, vitreous to dull luster, conchoidal fracture, opaque to translucent, colors range from white, grey, brown to black.
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Physical properties
Hardness of 7 on the Mohs scale, vitreous to dull luster, conchoidal fracture, opaque to translucent, colors range from white, grey, brown to black.
Formation & geological history
Formed through the diagenesis of siliceous oozes or the replacement of limestone by silica-rich groundwater in marine environments over millions of years.
Uses & applications
Historically used for tools and weapons (arrowheads, blades), fire-starting, and abrasive grit.
Geological facts
Chert is extremely durable and has been used by humans for stone tools for over two million years due to its sharp conchoidal fracture edges.
Field identification & locations
Can be identified in the field by its waxy luster, conchoidal fracture, and ability to scratch glass easily.
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