sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
Hardness 7 on Mohs scale; light brown to tan color with iron oxide staining; dull to waxy luster; conchoidal fracture with sharp edges; dense and microcrystalline structure.
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Physical properties
Hardness 7 on Mohs scale; light brown to tan color with iron oxide staining; dull to waxy luster; conchoidal fracture with sharp edges; dense and microcrystalline structure.
Formation & geological history
Formed through the accumulation of silica-rich microfossils or precipitation of silica in marine or lacustrine sedimentary environments.
Uses & applications
Historically used for making stone tools, arrowheads, and spark-striking flints. Modernly used in road aggregate, landscaping, and lapidary practice.
Geological facts
Chert breaks with a distinct conchoidal fracture, producing extremely sharp edges that were essential for ancient stone toolmakers.
Field identification & locations
Identified in the field by its hardness (scratches glass), smooth conchoidal fracture surfaces, and fine-grained waxy appearance. Commonly found in limestone and chalk formations worldwide.
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