sedimentary
Chert Nodule
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and typically gray, brown, or white colors.
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Physical properties
Hardness of 7 on the Mohs scale, waxy luster, conchoidal fracture, and typically gray, brown, or white colors.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich solutions during the Cenozoic or older geological eras.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp edges when fractured.
Geological facts
Chert was essential for early human survival and toolmaking, and varieties include flint, jasper, and agate.
Field identification & locations
Identify in the field by its distinctive conchoidal fracture and hardness that scratches glass; commonly found in limestone formations worldwide.
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