sedimentary

Flint or chert fragment

Microcrystalline quartz (SiO₂), likely flint/chert

AI-generated identification · may be incorrect

Hardness about 7 Mohs; tan to honey-brown, dull to waxy luster, very fine-grained and noncrystalline-looking. It commonly shows conchoidal fracture and lacks visible cleavage; apparent translucence may occur along thin edges.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica replaces or cementes sediments, commonly from biogenic silica in marine limestone or chalk. Most specimens are Paleozoic to Cenozoic, though age cannot be determined from the photograph.

Uses & applications

Used historically for sharp tools, fire-starting, and arrowheads; decorative chert is occasionally collected, but this small fragment has little commercial value.

Geological facts

Flint is technically a dark, dense variety of chert, while tan material is often called chert. Its sharp conchoidal edges made it important in prehistoric technology.

Field identification & locations

Common in limestone, chalk, gravel, and glacial deposits worldwide; inspect for waxy texture, curved fracture surfaces, and inability to scratch it with a steel knife. The image is consistent with chert but cannot exclude quartz-rich jasper or a weathered quartz fragment.