sedimentary
Flint
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, dark gray to black color with a weathered yellowish cortex, waxy to vitreous luster, and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, dark gray to black color with a weathered yellowish cortex, waxy to vitreous luster, and conchoidal fracture.
Formation & geological history
Formed by the chemical replacement of limestone or chalk by silica-rich groundwater in marine environments over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and fire-starting flint-lock mechanisms; currently collected as a lapidary material.
Geological facts
Flint is virtually identical to chert, though archaeologists often reserve the term flint specifically for the high-quality varieties found in chalk formations.
Field identification & locations
Easily identified by its sharp conchoidal edges, hardness that scratches glass, and characteristic weathering rind; found globally in chalk deposits.
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