sedimentary

Flint or chert fragment

Microcrystalline quartz (SiO₂), likely flint/chert

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, with waxy to dull luster, gray to brown color, and conchoidal fracture. This piece appears fine-grained and opaque, without visible crystal faces or cleavage; the pale coating may be weathering or cortex.

Identified August 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or fills pores in limestone, chalk, or other sediments, commonly during the Mesozoic–Cenozoic. The sharp edges indicate natural breakage or deliberate flaking, but the image alone cannot establish an artifact.

Uses & applications

Used historically for cutting tools and fire-starting, and currently as a lapidary, teaching, and decorative material; rarely used as aggregate. Common specimens generally have modest collector value.

Geological facts

Flint is a dense variety of chert, often associated with chalk and fossil-bearing marine sediments. Freshly fractured surfaces are usually sharper, smoother, and more glassy than weathered exteriors.

Field identification & locations

Test for a glassy conchoidal fracture and inability to scratch it with a steel knife; quartz-rich material should scratch ordinary glass. Common locations include chalk and limestone regions worldwide, especially England, France, the Great Lakes, and parts of the western United States.