sedimentary

Chert (flint) with a pale quartz vein

Microcrystalline quartz, SiO₂; the white vein is likely quartz or chalcedony

AI-generated identification · may be incorrect

Brown-gray, opaque to slightly translucent, with a dull-to-waxy luster and conchoidal fracture; quartz has Mohs hardness 7. The image does not establish crystal structure or specific gravity; chert is cryptocrystalline and about 2.6 g/cm³.

Identified October 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and hardens in sedimentary settings, often replacing carbonate sediment; the vein formed when silica-rich fluids filled a crack later. Its precise age cannot be determined from the photograph.

Uses & applications

Historically used for tools and sparks; attractive pieces may be collected or fashioned into small carvings and jewelry.

Geological facts

Chert breaks with sharp, curved surfaces, making it useful for prehistoric cutting tools.

Field identification & locations

Look for hardness, waxy appearance, and shell-like fracture; common in sedimentary formations worldwide. The pale crosscutting band is consistent with a later silica-filled fracture.