sedimentary

Chert or flint flake

Cryptocrystalline microcrystalline quartz (SiO₂), likely chert/flint

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown to gray-brown, dull to waxy luster, very fine-grained, with conchoidal fractures and sharp flake edges. No visible cleavage; specific gravity is approximately 2.6.

Identified September 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or precipitates within sediment, commonly limestone or chalk, during diagenesis. The shape and striking scars suggest a human-worked lithic flake, potentially prehistoric, but age cannot be determined from the image.

Uses & applications

Natural chert is used for aggregate and historically for fire-starting and stone tools; worked flakes are primarily archaeological or collectible objects rather than commercial materials.

Geological facts

Chert fractures into exceptionally sharp edges because of its homogeneous quartz-rich structure. Flint is generally a dark variety of chert associated especially with chalk deposits.

Field identification & locations

Identify it by its glassy/waxy surface, hardness, lack of cleavage, and curved conchoidal fractures; it should scratch glass. Common sources include limestone and chalk regions worldwide; archaeological context and professional testing are needed for authenticity and dating.