sedimentary

Chert / Flint Pebble

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs scale; Color: Dull brown to beige with iron staining; Luster: Dull to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Hardness: 6
Color: Dull brown to beige with iron staining
Luster: Dull to waxy

Identified June 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the accumulation of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation within limestone or chalk beds. This specimen shows significant rounding from river or glacial transport.

Uses & applications

Historically used for stone tools/arrowheads due to conchoidal fracturing; used today as a decorative landscape stone, in road construction, or as an abrasive.

Geological facts

Flint is a variety of chert. It was one of the first materials traded over long distances by prehistoric humans because of its ability to create sharp edges and sparks when struck with steel.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by a steel knife) and smooth, rounded surface indicating water wear. Commonly found in river beds, beaches, and sedimentary basins worldwide.