sedimentary

Flint (chert)

Microcrystalline quartz (SiO₂), variety of chert

AI-generated identification · may be incorrect

Dark gray to black with a waxy luster and pale weathered patches; typically Mohs hardness 7, with no cleavage and a conchoidal fracture. The small, sharp-edged fragment is consistent with flint, though the photo does not show enough detail for certainty.

Identified October 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms as silica-rich nodules or layers in sedimentary rocks, often from seafloor silica; deposits occur across many geological ages. Flint is especially common in Cretaceous chalk and limestone.

Uses & applications

Historically used for tools and sparks in fire-starting; today collected and occasionally used for knapping or decorative objects.

Geological facts

Flint’s hard, brittle texture and conchoidal fracture produce sharp edges when struck.

Field identification & locations

Look for a dense, fine-grained surface, curved fracture scars, and a waxy sheen; common in chalk and limestone regions. The specimen is too small and context-limited for a precise identification.