sedimentary

Flint (chert) fragment

Microcrystalline quartz (SiO₂), commonly called chert; possibly a worked flake

AI-generated identification · may be incorrect

Typically hardness 7 Mohs, waxy to dull luster, and conchoidal fracture; this small dark-brown fragment has sharp edges and a pale patch that may be cortex or another mineral. Individual crystals are too fine to see.

Identified October 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and recrystallizes in sedimentary rocks, often as nodules in limestone or chalk. Its age depends on its source deposit; the apparent flake shape may result from deliberate knapping, but the image alone cannot establish that.

Uses & applications

Used historically for cutting tools and fire-starting; today it is collected, studied archaeologically, and occasionally used decoratively.

Geological facts

Flint is a variety of chert prized for producing sharp edges when fractured. The pale area may be natural, but its identity is unclear from the photo.

Field identification & locations

Look for a very hard, fine-grained surface and curved, shell-like fracture scars; flint occurs widely in sedimentary formations. The specimen is too small and visually ambiguous to confirm workmanship or provenance.