sedimentary
Chert Pebble
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Brownish-tan with dark mottling, Luster: Dull to waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Brownish-tan with dark mottling, Luster: Dull to waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed by the precipitation of silica in sedimentary environments, typically as nodules in limestone or chalk beds. This specimen has been rounded by fluvial (river) or beach erosion.
Uses & applications
Historically used for stone tools and starting fires; currently used in construction aggregate and as decorative landscaping stones.
Geological facts
Chert is essentially the same material as flint. It is incredibly durable and can withstand significant transport along riverbeds without breaking apart.
Field identification & locations
Identified by its smoothness, conchoidal fracture (if chipped), and ability to scratch glass. Very common in riverbeds and glacial deposits.
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