sedimentary
Flint
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectMohs hardness of 7, typically dark gray to black, waxy to vitreous luster, and exhibits conchoidal fracture.
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Physical properties
Mohs hardness of 7, typically dark gray to black, waxy to vitreous luster, and exhibits conchoidal fracture.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich groundwater over millions of years.
Uses & applications
Historically used for making stone tools and fire-starting; currently valued by knappers, collectors, and for decorative landscaping.
Geological facts
Prehistoric humans heavily favored flint for weapon making due to its predictable, sharp conchoidal breakage patterns.
Field identification & locations
Identify in the field by its dark color, conchoidal fracture edges, and ability to scratch glass; commonly found embedded in chalk formations worldwide.
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