sedimentary
Flint (chert)
Microcrystalline quartz (SiO₂), a variety of chert
AI-generated identification · may be incorrectGray, fine-grained, with a dull to slightly waxy luster and curved conchoidal fracture surfaces. Quartz hardness is about 7 Mohs; the image does not reveal crystal structure directly.
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Physical properties
Gray, fine-grained, with a dull to slightly waxy luster and curved conchoidal fracture surfaces. Quartz hardness is about 7 Mohs; the image does not reveal crystal structure directly.
Formation & geological history
Forms when silica accumulates and replaces material in sedimentary rocks, commonly limestone or chalk. Chert occurs in rocks of many geological ages; this specimen’s age cannot be determined from the image.
Uses & applications
Historically used for tools and fire-starting; today collected and occasionally used for carving or decorative work.
Geological facts
The sharp, curved fracture edges are characteristic of flint and made it useful for prehistoric cutting tools.
Field identification & locations
Likely flint based on its gray color, dense texture, and conchoidal fractures; similar material occurs in chalk and limestone regions worldwide. Confirming its identity and provenance requires examination beyond the photograph.
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