sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, typically gray or brown with a waxy to vitreous luster and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, typically gray or brown with a waxy to vitreous luster and conchoidal fracture.
Formation & geological history
Formed through the chemical precipitation of silica from seawater or the accumulation of siliceous microfossils in deep marine environments.
Uses & applications
Historically used by early humans for making stone tools and weapons due to its sharp conchoidal fracture.
Geological facts
Chert that is dark-colored or black is commonly referred to as flint and was heavily used for fire-starting.
Field identification & locations
Identify in the field by its hardness (scratches glass), waxy luster, and smooth curved conchoidal breakage patterns.
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