sedimentary
Chert Pebble
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale), Color: light grey/tan, Luster: dull to waxy, Structure: cryptocrystalline, Cleavage: none (conchoidal fracture)
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Physical properties
Hardness: 7 (Mohs scale), Color: light grey/tan, Luster: dull to waxy, Structure: cryptocrystalline, Cleavage: none (conchoidal fracture)
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine environments; subsequently rounded by water erosion.
Uses & applications
Historically used for making stone tools; currently used in construction aggregate and as decorative river stones.
Geological facts
Chert is so hard it can scratch steel and was used by prehistoric humans to create sharp edges for arrowheads and knives.
Field identification & locations
Identified by its smooth, matte surface and fine-grained texture; commonly found in riverbeds, beaches, and glacial deposits.
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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