sedimentary
Flint
SiO2 (Microcrystalline Quartz)
Hardness of 7 on the Mohs scale, typically brown to dark grey or black in color, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture with no true cleavage, specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically brown to dark grey or black in color, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture with no true cleavage, specific gravity of 2.60 to 2.65.
Formation & geological history
Formed by the replacement of calcium carbonate with silica-rich solutions in chalk or limestone formations during the Cretaceous period.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in abrasives, landscaping, and decorative aggregates.
Geological facts
Flint is famous for its ability to produce sharp flakes when struck, making it one of the most important materials in human technological development during the Stone Age.
Field identification & locations
Easily identified in the field by its conchoidal fracture, sharp edges, and occurrence as nodules within chalk or limestone cliffs and beaches. Common worldwide.
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