sedimentary

Flint

Chert (Silicon dioxide, SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: typically dark grey, black, or deep brown; Luster: waxy to glassy; Structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture.

Hardness: 7 on Mohs scale
Color: typically dark grey, black, or deep brown
Luster: waxy to glassy

Identified May 16, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: typically dark grey, black, or deep brown; Luster: waxy to glassy; Structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture.

Formation & geological history

Forms as nodules in sedimentary rocks like chalk or limestone through the replacement of calcium carbonate with silica from organic sources like sponges or diatoms.

Uses & applications

Historically used for stone tools and weapons (arrowheads); currently used in abrasives, ceramics, and as a lighter striker in survival gear.

Geological facts

Flint was the primary material for the Neolithic revolution, allowing humans to create sharp tools and start fires. It occurs globally, often found inside Cretaceous period chalk deposits.

Field identification & locations

Identify by its characteristic conchoidal fracture (smooth, curved breaks like glass) and its ability to create sparks when struck against steel. Commonly found in chalk shorelines and riverbeds.