sedimentary

Flint or chert flake

Microcrystalline quartz (SiO₂), commonly chert/flint

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; gray-white to brown, with a dull to waxy luster and conchoidal fracture. The sharp edges and shell-like break are characteristic of fractured silica-rich rock.

Identified August 8, 2026More sedimentary →

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Physical properties

Hardness about 6.5–7 Mohs; gray-white to brown, with a dull to waxy luster and conchoidal fracture. The sharp edges and shell-like break are characteristic of fractured silica-rich rock.

Formation & geological history

Chert forms when microcrystalline quartz replaces or accumulates from silica-rich marine sediments, commonly in limestone; ages range from Paleozoic to Cenozoic. This appears to be a broken or knapped flake rather than a complete bedrock fragment.

Uses & applications

Historically used for stone tools, fire-starting, and arrowheads; today it is mainly a teaching or archaeological/collector specimen. Ordinary fragments have little commercial value.

Geological facts

Chert and flint are mineralogically similar varieties of microcrystalline quartz; flint often refers to dark, high-quality chert. Fresh conchoidal edges can be razor sharp.

Field identification & locations

Identify it by its very hard, glass-like fracture, inability to scratch with a steel knife, and lack of visible large crystals; common sources include limestone regions worldwide. It may be archaeological if deliberate flaking or retouch is present.