sedimentary
Chert / Flint
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, colors range from brown, gray, to white with a waxy to vitreous luster, cryptocrystalline structure, exhibits conchoidal fracture with no true cleavage, specific gravity of around 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from brown, gray, to white with a waxy to vitreous luster, cryptocrystalline structure, exhibits conchoidal fracture with no true cleavage, specific gravity of around 2.60 to 2.65.
Formation & geological history
Formed via the chemical precipitation of silica from aqueous solutions, often replacing carbonate rocks (like limestone) in marine environments during the Cretaceous or other periods.
Uses & applications
Historically used for making stone tools, arrowheads, and spark-striking fire starters; occasionally used as decorative landscaping stones or tumbling material.
Geological facts
Chert and flint are chemically identical forms of microcrystalline quartz. Flint is typically darker and associated with chalk deposits, while chert is found in limestone.
Field identification & locations
Easily identified by its conchoidal fracture and extreme hardness (can easily scratch glass). Found globally within sedimentary limestone and chalk formations.
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