Sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness 6.5-7 on Mohs scale, typically occurs in massive form. Conchoidal fracture. Color can vary widely; this piece shows tan, light brown, and gray hues. Waxy to dull luster.
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Physical properties
Hardness 6.5-7 on Mohs scale, typically occurs in massive form. Conchoidal fracture. Color can vary widely; this piece shows tan, light brown, and gray hues. Waxy to dull luster.
Formation & geological history
Formed as a chemical sedimentary rock, typically from the precipitation of silica from groundwater or oceanic water, often replacing other minerals or organic material.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) due to its conchoidal fracture. Sometimes used as a low-grade road material or collected as a specimen.
Geological facts
Flint is a type of chert that occurs specifically in chalk or marly limestone deposits. The sharp edges produced when fractured made it invaluable to early humans.
Field identification & locations
Identified by its waxy luster, hardness (scratches glass), and conchoidal fracture. Often found as nodules in limestone or as layered deposits. Look for smooth, curved broken surfaces.
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