sedimentary
Chert / Flint Pebble
Cryptocrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Brown, tan, or grey including earthy shades, Luster: Dull to waxy, Crystal structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Brown, tan, or grey including earthy shades, Luster: Dull to waxy, Crystal structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.65
Formation & geological history
Formed by the accumulation of siliceous remains of organisms like diatoms or through chemical precipitation in sedimentary environments. Common in marine limestone and chalk deposits.
Uses & applications
Used historically for stone tools (knapping) due to its sharp edges; currently used in construction as road metal and in glass manufacturing or as common landscaping rocks.
Geological facts
Flint is a variety of chert that was essential to prehistoric humans for fire-starting and weapons. It breaks into razor-sharp edges which remain sharper than surgical steel.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surfaces if broken. Found globally in riverbeds and pebble beaches.
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