sedimentary

Gray flint/chert flake or tool

Microcrystalline quartz (SiO₂), commonly chalcedony

AI-generated identification · may be incorrect

Hardness about 7 Mohs; gray to brown, waxy-to-dull luster, very fine cryptocrystalline structure, no visible cleavage, and conchoidal fracture. The deliberate-looking flake scars and sharp serrated edge suggest a chipped stone artifact rather than a naturally broken fragment.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica replaces or accumulates within sedimentary rocks, often limestone, during diagenesis; its exact geological age cannot be determined from the photograph. This specimen may have been intentionally knapped by humans, potentially prehistoric, but that requires archaeological examination.

Uses & applications

Chert is used historically for cutting tools, fire-starting, and construction aggregate; archaeological flakes can have cultural and collector value. Do not clean, modify, or remove it from a find site without checking local heritage laws.

Geological facts

Its sharp edge, percussion-like flaking, and bulbous/conchoidal fracture are consistent with knapping. Similar material occurs as flint nodules in chalk and limestone formations worldwide.

Field identification & locations

Identify it by testing for glassy conchoidal fracture, lack of cleavage, and hardness sufficient to scratch glass; microscopic edge-wear or platform features can confirm tooling. Common sources include Europe, the Middle East, North America, and Australia.