sedimentary

Flint or chert flake

Microcrystalline quartz (SiO₂), likely fossiliferous or cortex-bearing chert

AI-generated identification · may be incorrect

Opaque tan-brown stone with a dull to slightly waxy luster, conchoidal fracture, sharp flake edges, and a darker rough outer cortex. Hardness is about 6.5–7 Mohs; no visible cleavage; specific gravity approximately 2.60.

Identified September 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica replaces or accumulates within marine or freshwater sediment, commonly during the Cretaceous or other Phanerozoic periods; the exact age cannot be determined from the photograph. Its triangular shape and bulbous fracture surface strongly suggest intentional prehistoric knapping, though natural breakage is possible.

Uses & applications

Historically used for cutting tools, spear and arrow points, fire-starting, and scraping; attractive pieces may be collected as archaeological lithics or geological specimens. It has little commercial value as ordinary raw material.

Geological facts

The sharp edge results from conchoidal fracture, a diagnostic property of quartz-rich stone. Dark markings along the base may be cortex, impurities, or weathering rather than a distinct fossil.

Field identification & locations

Identify it by testing hardness against glass, looking for a waxy surface and curved fracture ripples, and checking for uniform microcrystalline texture; avoid destructive testing if archaeological origin is possible. Chert is common in limestone and chalk regions worldwide, including Europe, North America, and the Middle East.