sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Gray, tan, and brown with a waxy to dull luster, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Gray, tan, and brown with a waxy to dull luster, Crystal Structure: Microcrystalline/Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation in sedimentary environments. Often found as nodules or layers in limestone or chalk.
Uses & applications
Historically used for stone tools and starting fires (flint); currently used in road construction, as an abrasive, and for lapidary work.
Geological facts
Because it breaks with a conchoidal fracture, it creates edges as sharp as a razor. It was the primary material for spearheads and arrowheads for thousands of years.
Field identification & locations
Look for a smooth, glass-like break surface and a sharp edge where fractured. It will scratch steel and glass easily. Commonly found in riverbeds or eroded limestone deposits.
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