sedimentary
Flint
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, typically dark gray or brown with a waxy luster and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark gray or brown with a waxy luster and conchoidal fracture.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich solutions during the Cretaceous period.
Uses & applications
Historically used for prehistoric stone tools and fire-starting; currently used for decorative landscaping and tumbling.
Geological facts
Flint produces sparks when struck against steel due to its high hardness and brittle fracture, making it essential for early firearms.
Field identification & locations
Identify by its smooth waterworn exterior, conchoidal fracture surfaces, and ability to scratch glass easily.
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