sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs scale), Color: tan, brown, gray, black, Luster: waxy to dull, Crystal structure: microcrystalline/cryptocrystalline, Cleavage: none (conchoidal fracture), Specific gravity: 2.5-2.8
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: tan, brown, gray, black, Luster: waxy to dull, Crystal structure: microcrystalline/cryptocrystalline, Cleavage: none (conchoidal fracture), Specific gravity: 2.5-2.8
Formation & geological history
Formed from silica-rich fluids precipitating in sedimentary rocks, often replacing limestone or chalk. Can be biogenic (from siliceous skeletons of diatoms or radiolarians) or inorganic.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its conchoidal fracture. Sometimes used as a road surfacing material or in landscaping.
Geological facts
Flint is a specific type of chert found in chalk or marly limestone. It was highly prized by early humans for tool-making and starting fires.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster, and smooth, curved (conchoidal) fracture surfaces. Commonly found as nodules or layers in sedimentary rock formations.
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