sedimentary
Chert (Jasper variety)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs), Color: Reddish-brown to tan, Luster: Dull to waxy, Crystal Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Reddish-brown to tan, Luster: Dull to waxy, Crystal Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed from the recrystallization of silica-rich fluids within sedimentary rock layers, often associated with ancient seafloors and hydrothermal activity.
Uses & applications
Historically used for making stone tools; currently used in jewelry (as a gemstone), landscaping, and as a decorative specimen for collectors.
Geological facts
Chert is so durable that it can survive long periods of weathering and transport by water, which is why it is frequently found as rounded pebbles in gravel pits and stream beds.
Field identification & locations
Identify in the field by its hardness (it can scratch glass), its smooth conchoidal fracture, and its lack of visible grains. Common in limestone regions and river beds.
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
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Sandstone or Siltstone
Arenite (if sandstone)
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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