sedimentary
Chert (Jasper/Agate)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs), Color: Mottled brown, black, and tan, Luster: Waxy to vitreous, Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.7
- Hardness
- 6
Identified More sedimentary →
Explore Chert (Jasper/Agate) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs), Color: Mottled brown, black, and tan, Luster: Waxy to vitreous, Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the precipitation of silica from aqueous fluids or the accumulation of silica-rich organic debris (like radiolarians) on the ocean floor, subsequently undergoing lithification.
Uses & applications
Historically used for stone tools (flintknapping); currently used in jewelry as cabochons, for decorative lapidary work, and as landscaping gravel.
Geological facts
This specimen appears to be a stream-tumbled pebble. Chert is extremely durable and chemically stable, often surviving intense weathering that destroys other rock types.
Field identification & locations
Identify by its high hardness (it will scratch glass), smooth waxy texture, and shell-like (conchoidal) fracture pattern. Commonly found in riverbeds, gravel pits, and coastal areas as rounded pebbles.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary