sedimentary

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Dark brown to black, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6

Identified June 22, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale), Color: Dark brown to black, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6

Formation & geological history

Formed through the accumulation of siliceous remains such as radiolaria or diatoms in marine environments, or from the chemical precipitation of silica-rich fluids. Can be found in rocks from the Precambrian era to the present.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges; currently used for decorative purposes, landscape stone, and as a raw material for silicon production.

Geological facts

Chert produces sparks when struck against steel, leading to its widespread use in flintlock firearms. It was one of the first materials traded over long distances by prehistoric humans.

Field identification & locations

Identify in the field by its hardness (scratches glass) and its curved, shell-like (conchoidal) fracture pattern. Commonly found in limestone or chalk beds.