sedimentary
Yellow Chert (River Pebble)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to yellow-brown; Luster: Waxy to dull; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan to yellow-brown
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Yellow Chert (River Pebble) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Tan to yellow-brown; Luster: Waxy to dull; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed as chemical precipitates or as biochemical deposits on the ocean floor, often replacing carbonate materials. This specific specimen has been subsequentely weathered and rounded through fluvial (river) transport.
Uses & applications
Historically used for stone tools (arrowheads). Today used in landscaping, road construction, and as decorative river stones.
Geological facts
Chert is so hard it can create sparks when struck against steel. It is nearly identical in composition to flint, though usually lighter in color. The yellow hue is often due to trace iron oxide (limonite) inclusions.
Field identification & locations
Look for a smooth, waxy texture and conchoidal (shell-like) fractures where broken. It will easily scratch glass. Commonly found in riverbeds, gravel pits, and sedimentary outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary