sedimentary
Flint (chert)
Microcrystalline quartz (SiO₂), commonly called chert or flint
AI-generated identification · may be incorrectThe specimen appears dark gray-brown with pale weathered patches and a waxy-to-dull luster. Chert is about 7 on the Mohs scale, has a microcrystalline structure, and breaks with curved, sharp conchoidal fractures rather than obvious cleavage.
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Physical properties
The specimen appears dark gray-brown with pale weathered patches and a waxy-to-dull luster. Chert is about 7 on the Mohs scale, has a microcrystalline structure, and breaks with curved, sharp conchoidal fractures rather than obvious cleavage.
Formation & geological history
Forms when silica-rich sediment or dissolved silica replaces or fills sedimentary material, often in limestone or chalk. Its age depends on the deposit; chert forms in many geological periods.
Uses & applications
Historically used for tools, sparks, and fire-starting; today it is mainly collected or used decoratively. This small rough piece has little commercial value.
Geological facts
Flint is a variety of chert and was widely knapped into prehistoric blades and arrowheads.
Field identification & locations
Look for a hard, fine-grained texture and sharp, curved fracture surfaces; weathered outer surfaces may contrast with darker interiors. Chert occurs worldwide in sedimentary rocks; the image alone cannot confirm this identification.
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