sedimentary

Flint or chert flake

Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities

AI-generated identification · may be incorrect

Typically 6.5–7 Mohs hardness, waxy to dull luster, conchoidal fracture, no cleavage, and gray, brown, or translucent coloration. The specimen appears to be a worked or naturally fractured flake with a sharp edge; exact identification is limited by the image.

Identified August 9, 2026More sedimentary →

Explore Flint or chert flake in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Chert forms when silica-rich groundwater replaces or fills pores in limestone and other sediments, generally during diagenesis. It occurs in sedimentary rocks of many geological ages; this piece may have been intentionally knapped, but the image alone cannot confirm human manufacture.

Uses & applications

Used historically for cutting tools, fire-starting, and arrowheads; today it is mainly collected, studied archaeologically, or displayed. Common specimens usually have little commercial value.

Geological facts

Its conchoidal fracture produces sharp edges and curved ripple marks, a diagnostic feature of quartz-rich chert. Flint is often considered a dark, high-quality variety of chert, especially in archaeological contexts.

Field identification & locations

Common in limestone formations, river gravels, and glacial deposits worldwide, especially England, France, the Great Lakes region, and the central United States. Check for conchoidal ripples, a glassy wax-like fracture, and absence of visible grains; a sharp regular edge may indicate knapping.