sedimentary

Flint

SiO2 (Microcrystalline Quartz / Chert)

Hardness of 7 on the Mohs scale, colors range from dark grey, black, brown to white, waxy to vitreous luster, conchoidal fracture with sharp edges, no cleavage, specific gravity of 2.60 to 2.65.

Identified August 3, 2026More sedimentary →

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Physical properties

Hardness of 7 on the Mohs scale, colors range from dark grey, black, brown to white, waxy to vitreous luster, conchoidal fracture with sharp edges, no cleavage, specific gravity of 2.60 to 2.65.

Formation & geological history

Formed chemically or biochemically in marine environments, typically as nodules or concretions within chalk or limestone formations during the Cretaceous period.

Uses & applications

Historically used for making stone tools, arrowheads, and striking fire. Modern uses include decorative gravel, ball mills for grinding, and specialized construction.

Geological facts

Flint was one of the earliest materials manipulated by early humans to create cutting tools and weapons due to its ability to fracture conchoidally into extremely sharp edges.

Field identification & locations

Easily identified by its dark, often glossy appearance when wet, conchoidal fracture patterns, and high hardness capable of scratching glass and producing sparks with steel. Found globally in chalk and limestone deposits.