sedimentary
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: tan, white, and ochre yellow, Luster: dull to waxy, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: tan, white, and ochre yellow, Luster: dull to waxy, Crystal Structure: Microcrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like diatoms or radiolaria) or chemical precipitation in marine environments. This specimen appears water-worn, likely from a riverbed or coastal area.
Uses & applications
Historically used for stone tools (knapping) due to its sharp edges. Currently used in road construction, as decorative landscaping stone, and occasionally in jewelry as common jasper.
Geological facts
Chert is so durable it often survives the weathering process that destroys the surrounding limestone or chalk host rock. Ancient humans favored this material for making arrowheads and scrapers.
Field identification & locations
Identify by its hardness (scratches glass), smooth texture, and curved, shell-like fracture lines. Found globally in sedimentary basins and gravel deposits.
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