sedimentary
Chert (Yellow Jasper)
Cryptocrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal; Cleavage: None
- Hardness
- 6
- Color
- Yellowish-brown to tan
- Luster
- Dull to waxy
Identified More sedimentary →
Explore Chert (Yellow Jasper) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal; Cleavage: None
Formation & geological history
Formed through the accumulation of silica-rich microfossils like diatoms or radiolarians, or via chemical precipitation from silica-saturated fluids in limestone or ocean floor environments.
Uses & applications
Historically used for stone tools and arrowheads; currently used for lapidary work, jewelry (as 'Jasper'), and as a high-durability landscaping or road material.
Geological facts
Chert is so hard it can scratch steel and was used by ancient humans to create sparks for fire and sharp edges for hunting.
Field identification & locations
Identify by its 'flint-like' waxy texture, curved (conchoidal) breaks, and hardness. Often found in riverbeds or as nodules within limestone outcrops.
More like this
Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary