sedimentary

Chert

Silicon dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7; Color: various, often pale, brown, gray, or banded; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture

Hardness: 6
Color: various, often pale, brown, gray, or banded
Luster: waxy to dull

Identified September 21, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7; Color: various, often pale, brown, gray, or banded; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture

Formation & geological history

Forms as a chemical precipitate or from the accumulation of silica-rich biological remains (like diatoms or radiolarians) in marine environments.

Uses & applications

Historically used for making stone tools and fire-starting (flint). Occasionally used as a semi-precious stone if attractively banded.

Geological facts

Flint is a specific type of chert found in chalk or marly limestone. The piece shown appears to have been worked or struck, showing conchoidal fractures typical of knapping.