sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectMohs hardness 7, waxy to dull luster, conchoidal fracture with sharp edges, microcrystalline structure, light tan to greyish-blue color with yellowish iron staining.
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Physical properties
Mohs hardness 7, waxy to dull luster, conchoidal fracture with sharp edges, microcrystalline structure, light tan to greyish-blue color with yellowish iron staining.
Formation & geological history
Formed in marine or sedimentary environments via precipitation of silica-rich solutions or replaced organic material like radiolarians and sponges.
Uses & applications
Historically used for knapping arrowheads and starting fires. Modern uses include abrasive materials, ballast, and lapidary art.
Geological facts
Because of its cryptocrystalline nature, chert breaks with sharp conchoidal edges, making it the most important material for Stone Age tools worldwide.
Field identification & locations
Identified by high hardness (scratches glass), prominent conchoidal fracture, smooth waxy texture, and lack of cleavage. Commonly found in limestone and chalk formations worldwide.
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