sedimentary
Chert (Jasper/Flint variation)
Chert (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs), Color: Dark brown or grayish with lighter bands, Luster: Waxy to vitreous (especially when tumbled), Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs), Color: Dark brown or grayish with lighter bands, Luster: Waxy to vitreous (especially when tumbled), Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments. Often found as nodules within limestone or as bedded deposits. Ages vary from Precambrian to Cenozoic.
Uses & applications
Historical use for sharp tools/arrowheads. Modern use as decorative landscaping stones, road gravel, and tumbled stones for rock collectors.
Geological facts
Chert is so hard it can create sparks when struck against steel. It was one of the most important minerals for early human survival for making fire and hunting tools.
Field identification & locations
Identify by its waxy texture, high hardness (will scratch glass), and rounded 'river-stone' appearance if eroded. Commonly found in riverbeds and limestone outcrops.
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