sedimentary
Flint
SiO2 (Microcrystalline Quartz / Chert)
Hardness of 7 on the Mohs scale, colors range from grey, brown, to black, vitreous to waxy luster, amorphous or microcrystalline cryptocrystalline structure, conchoidal fracture with sharp edges, specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from grey, brown, to black, vitreous to waxy luster, amorphous or microcrystalline cryptocrystalline structure, conchoidal fracture with sharp edges, specific gravity of 2.60 to 2.65.
Formation & geological history
Formed through chemical replacement in chalk or limestone formations during the Cretaceous period, where silica-rich fluids precipitated microcrystalline quartz.
Uses & applications
Historically used for stone tools, arrowheads, and striking fire. Currently used in specialized construction, grinding mills, and as a collector's specimen.
Geological facts
Flint was one of the earliest materials mastered by early humans for toolmaking due to its predictable conchoidal fracture which creates razor-sharp edges.
Field identification & locations
Easily identified by its smooth, conchoidal fracture surfaces, waxy luster, and high hardness that easily scratches glass. Found worldwide in chalk deposits.
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