sedimentary
Flint / Chert
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and typically brown, gray, or black coloration.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, and typically brown, gray, or black coloration.
Formation & geological history
Forms through the chemical replacement of limestone or chalk by silica-rich groundwaters in marine environments.
Uses & applications
Historically used for making stone tools and fire-starting; currently used in abrasives, landscaping, and decorative items.
Geological facts
Flint produces sparks when struck against steel due to its extreme hardness and microcrystalline structure.
Field identification & locations
Identify by its distinct conchoidal fracture and waxy luster; commonly found in chalk deposits and river gravels.
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Fossiliferous Sedimentary Rock
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