sedimentary
Banded Chert
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Dark grey, tan, and brown banding, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline (microscopic quartz), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Identified More sedimentary →
Explore Banded Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: Dark grey, tan, and brown banding, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline (microscopic quartz), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of siliceous remains of microscopic organisms (like diatoms or radiolarians) or by chemical precipitation. The banding indicates cyclical depositional environments in marine or lake settings.
Uses & applications
Historically used for stone tools (arrowheads/scrapers) due to sharp edges; currently used for lapidary work, jewelry, and as a component in construction aggregate.
Geological facts
Chert is one of the most durable sedimentary rocks. It was the primary material for prehistoric toolmaking globally. Banded varieties are often related to iron formations or rhythmic sediment changes.
Field identification & locations
Identify in the field by its distinct conchoidal (shell-like) fracture patterns, extreme hardness (will scratch glass), and waxy texture. Commonly found in limestone or dolomite beds.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary