sedimentary

Brown chert (possible flint)

Microcrystalline quartz, SiO₂; chert

AI-generated identification · may be incorrect

Opaque brown, fine-grained, dull to waxy surface with irregular, sharp edges; quartz hardness about 7 and no cleavage. The image suggests a small chipped piece, but exact identification is uncertain from appearance alone.

Identified October 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and recrystallizes in sedimentary settings, often replacing carbonate sediments; its age depends on the host formation.

Uses & applications

Historically used for cutting tools and fire-starting; today collected or used in crafts and knapping.

Geological facts

Chert breaks with a curved, shell-like (conchoidal) fracture, producing sharp edges.

Field identification & locations

Look for a very fine texture, hardness sufficient to scratch glass, and conchoidal fracture; occurs in sedimentary rocks worldwide. Similar brown stones can be other materials, so a field test or closer view may be needed.