sedimentary

Yellow Chert Pebble

Microcrystalline Quartz (SiO2)

Hardness: 7 Mohs scale; Color: Dull yellow to mustard; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7. Often smooth and water-worn in pebble form.

Hardness: 7 Mohs scale
Color: Dull yellow to mustard
Luster: Waxy to dull

Identified July 8, 2026More sedimentary →

Explore Yellow Chert Pebble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed via the accumulation of siliceous remains of microscopic organisms (like radiolaria) or chemical precipitation from silica-rich fluids in sedimentary basins. This specimen is a river-rounded or beach-worn pebble.

Uses & applications

Historically used for stone tools (flintknapping); current uses involve landscaping, decorative gravel, and occasionally as a lapidary material for tumbling.

Geological facts

Yellow chert gets its color from iron oxide inclusions like goethite or limonite. It is extremely durable and can survive long-distance transport in rivers and glacial till.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife) and waxy, smooth texture. Look for conchoidal (shell-like) fractures on broken edges. Common in riverbeds and gravel deposits worldwide.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary