sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
Mohs hardness 7, waxy to vitreous luster, conchoidal fracture, sharp edges, dark gray to brownish color with white outer weathering rind
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Physical properties
Mohs hardness 7, waxy to vitreous luster, conchoidal fracture, sharp edges, dark gray to brownish color with white outer weathering rind
Formation & geological history
Forms chemically or biochemically in marine environments through accumulation of siliceous oozes or replacement of carbonate rocks
Uses & applications
Historically used for stone tools and flintknapping; modern uses include construction aggregate and decorative specimens
Geological facts
Flint was one of the earliest materials used by early humans to fashion sharp tools, arrowheads, and spark-producing fire starters
Field identification & locations
Identified by its extreme hardness, shell-like (conchoidal) fracture pattern, and waxy luster. Commonly found in limestone beds and gravel deposits worldwide
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