sedimentary
Chert (Arrowhead Artifact)
Chert (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Brown/Grey, Luster: Waxy to dull, Crystal Structure: Microcrystalline quartz, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Identified More sedimentary →
Explore Chert (Arrowhead Artifact) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: Brown/Grey, Luster: Waxy to dull, Crystal Structure: Microcrystalline quartz, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed as nodules in limestone or chalk through the accumulation of silica-rich organic remains (like radiolarians). This specimen was later culturally modified by flintknapping.
Uses & applications
Historically used for stone tools and weapons (projectile points); currently valued as an archaeological artifact and for hobbyist flintknapping.
Geological facts
Chert was one of the most important raw materials for early humans because its conchoidal fracture allows it to be shaped into razor-sharp edges.
Field identification & locations
Identify by the waxy texture, extreme hardness (scratches glass), and the presence of flake scars from intentional sharpening. Commonly found in riverbeds or eroded limestone deposits.
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