sedimentary

Chert (Flint pebble)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: Gray, tan, white, and dark brown/black banding. Luster: Dull to waxy. Crystal Structure: Microcrystalline (trigonal). Cleavage: None (conchoidal fracture).

Hardness: 7 on Mohs scale
Color: Gray, tan, white, and dark brown/black banding
Luster: Dull to waxy

Identified July 26, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale. Color: Gray, tan, white, and dark brown/black banding. Luster: Dull to waxy. Crystal Structure: Microcrystalline (trigonal). Cleavage: None (conchoidal fracture).

Formation & geological history

Chert forms through chemical weathering and precipitation of silica-rich fluids in sedimentary basins or marine environments, often replacing organic carbonate material or precipitating out of solution.

Uses & applications

Historically used for stone tools, arrowheads, and fire-starting flint. Today, used as road aggregate, construction material, and decorative landscaping pebble.

Geological facts

Chert and flint produce sharp conchoidal fractures when struck, making them essential materials for early human technology during the Stone Age.

Field identification & locations

Identified by its extreme hardness (scratches glass), waxy to dull texture, and sharp, shell-like (conchoidal) fracture edges. Commonly found along riverbeds, beaches, and chalk/limestone formations worldwide.