sedimentary

Chert (Flint)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Gray, tan, brown, and translucent; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Gray, tan, brown, and translucent
Luster: Waxy to dull

Identified July 9, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Gray, tan, brown, and translucent; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich organic remains (diatoms, radiolaria) or chemical precipitation from groundwater within limestone or chalk beds. It is often found in geological strata ranging from Precambrian to Cenozoic.

Uses & applications

Historically used for stone tools and weapons. Modern uses include road surfacing, decorative landscaping, and as a component in ceramics.

Geological facts

Chert possesses a conchoidal fracture which allows it to be knapped into razor-sharp edges. It was one of the most vital materials for early human survival.

Field identification & locations

Identify by its extreme hardness (scratches glass) and smooth, curved fracture surfaces. Commonly found in creek beds or as nodules protruding from weathered limestone outcrops.