sedimentary

Chert (Flint)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs scale; Color: Cream to white with brown weathering; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None, exhibits conchoidal fracture

Hardness: 7 Mohs scale
Color: Cream to white with brown weathering
Luster: Waxy to dull

Identified May 3, 2026More sedimentary →

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Physical properties

Hardness: 7 Mohs scale; Color: Cream to white with brown weathering; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None, exhibits conchoidal fracture

Formation & geological history

Biogenic or chemical precipitation of silica in marine environments, often replacing carbonate material; can date from Precambrian to Cenozoic eras.

Uses & applications

Historically used for making stone tools (arrowheads); currently used in road construction, landscaping, and occasionally as decorative gravel or for fire-starting kits.

Geological facts

Because it fractures conchoidally into very sharp edges, chert was the primary material for survival technology for thousands of years. It occurs as nodules or layers in limestone.

Field identification & locations

Identify by its hardness (cannot be scratched by steel), waxy texture, and the way it breaks into smooth curves. Often found in riverbeds or limestone outcroppings.