sedimentary

Chert (possibly a worked stone flake)

Microcrystalline quartz, SiO₂

AI-generated identification · may be incorrect

Brown, dull to slightly waxy surface; chert has Mohs hardness about 7, no cleavage, and a very fine-grained crystalline structure. The triangular shape and sharp edges may indicate it was intentionally chipped into a tool or projectile point.

Identified October 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich material accumulates and recrystallizes, often in sedimentary rocks; it occurs across many geological ages. If shaped, this piece was made by flintknapping, but its age cannot be determined from the image.

Uses & applications

Chert is used for cutting tools and historically for fire-starting; worked pieces are collected as archaeological or lithic artifacts.

Geological facts

Chert fractures conchoidally, producing sharp edges that made it valuable to prehistoric toolmakers.

Field identification & locations

Look for a smooth, fine-grained texture and curved fracture surfaces; the apparent flake shape alone does not establish its age or whether it is an artifact. Chert is widespread in sedimentary formations worldwide.