sedimentary
Flint
Silicon dioxide (SiO2) - Microcrystalline Quartz
Hardness of 7 on the Mohs scale; dark gray to black color with a waxy to vitreous luster; cryptocrystalline structure; conchoidal fracture with very sharp edges; specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 7 on the Mohs scale; dark gray to black color with a waxy to vitreous luster; cryptocrystalline structure; conchoidal fracture with very sharp edges; specific gravity of 2.60 to 2.65.
Formation & geological history
Formed through the chemical replacement of calcium carbonate in limestone or chalk by silica-rich groundwaters over millions of years during the Cretaceous and other sedimentary periods.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in abrasives, ceramics, and occasionally for decorative landscaping or historical reenactments.
Geological facts
Flint has been used by early humans for over two million years to create sharp cutting tools and weapons due to its unique conchoidal fracture pattern.
Field identification & locations
Found predominantly as nodules within chalk or limestone formations worldwide. Easily identified by its dark color, waxy luster, conchoidal fracture, and ability to produce sparks when struck against steel.
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