sedimentary
Chert or Jasper
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: dull green to brown, Luster: waxy to vitreous, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal
Identified More sedimentary →
Explore Chert or Jasper in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: dull green to brown, Luster: waxy to vitreous, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed by the precipitation of silica from seawater or the accumulation of silica-rich microfossils. Often found in nodules within limestone or as bedded deposits.
Uses & applications
Used historically for stone tools and arrowheads; currently used in jewelry (lapidary), as a gemstone, and in construction aggregate.
Geological facts
The smooth, waxy surface and sharp edges once broken made this a primary material for prehistoric humans to create cutting tools.
Field identification & locations
Field identification involves checking for a waxy luster and conchoidal (shell-like) fracture. It will easily scratch glass and cannot be scratched by a steel knife.
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