sedimentary

Chert (Jasper-like Silicate)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Brown, tan, and dark grey banding; Luster: Dull to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture).

Hardness: 7 on Mohs scale
Color: Brown, tan, and dark grey banding
Luster: Dull to waxy

Identified July 5, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brown, tan, and dark grey banding; Luster: Dull to waxy; Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from silica-rich fluids in sedimentary basins. Hardening occurs through deep burial and chemical alteration over millions of years.

Uses & applications

Used historically for stone tools and arrowheads due to its sharp edges; currently used for decorative purposes, landscape gravel, and as semi-precious lapidary material.

Geological facts

Chert is so hard it can strike sparks against steel. It is one of the most common materials used by early humans for lithic technology across the globe.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surfaces. Commonly found in riverbeds or within limestone formations.