sedimentary
Flint
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, dark grey to black color, waxy to vitreous luster, and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, dark grey to black color, waxy to vitreous luster, and conchoidal fracture.
Formation & geological history
Formed through the chemical replacement of calcium carbonate in limestone by silica-rich solutions during the Cretaceous period.
Uses & applications
Historically used for making stone tools and fire-starting; currently utilized in decorative construction and abrasive grinding.
Geological facts
Flint produces sparks when struck against steel due to its high hardness and brittle fracture properties. It was extensively used by early humans for weaponry.
Field identification & locations
Identify by its distinctive conchoidal fracture, sharp edges when broken, and waxy luster. Commonly found in chalk and limestone formations worldwide.
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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