sedimentary
Flint
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness 7 on the Mohs scale, typically dark gray or black with a waxy luster, conchoidal fracture, and cryptocrystalline structure.
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Physical properties
Hardness 7 on the Mohs scale, typically dark gray or black with a waxy luster, conchoidal fracture, and cryptocrystalline structure.
Formation & geological history
Forms by the replacement of calcium carbonate by silica-rich solutions in chalk or limestone formations during the Cretaceous period.
Uses & applications
Historically used for making stone tools, arrowheads, and fire-striking implements; modern use includes industrial grinding.
Geological facts
Prehistoric humans heavily prized flint for its sharp conchoidal fracture, which allows it to be shaped into precise cutting edges.
Field identification & locations
Identified easily by its conchoidal fracture and lack of reaction to acid; commonly found as nodules within chalk beds globally.
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