sedimentary
Flint / Chert
Silicon dioxide (Microcrystalline quartz, SiO2)
Hardness of 7 on the Mohs scale, colors range from gray, brown, to dark green/black, vitreous to waxy luster, cryptocrystalline structure, no cleavage (exhibits characteristic conchoidal fracture)
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Physical properties
Hardness of 7 on the Mohs scale, colors range from gray, brown, to dark green/black, vitreous to waxy luster, cryptocrystalline structure, no cleavage (exhibits characteristic conchoidal fracture)
Formation & geological history
Formed through the replacement of calcium carbonate by silica-rich solutions in sedimentary environments such as chalk or limestone formations, typically over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in abrasives, landscaping, and decorative knapping.
Geological facts
Flint was one of the earliest materials manipulated by early humans for weaponry and fire-making due to its predictable conchoidal fracture.
Field identification & locations
Easily identified in the field by its smooth, weathered outer cortex, sharp conchoidal edges when broken, and ability to scratch glass.
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