sedimentary

Chert (Yellow/Tan Jasper)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Tan, yellow, and brown banding/mottling; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Tan, yellow, and brown banding/mottling
Luster: Waxy to vitreous

Identified June 28, 2026More sedimentary →

Explore Chert (Yellow/Tan Jasper) 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 organisms or precipitation from silica-rich fluids in sedimentary environments. Often found as nodules in limestone or as stream-tumbled pebbles.

Uses & applications

Used historically for stone tools and weapons due to its sharp edges; currently used in jewelry (as jasper), rock tumbling for collectors, and as decorative aggregate.

Geological facts

Chert and Jasper were among the most important materials for prehistoric humans to create arrowheads and scrapers. The yellow color is usually caused by the presence of goethite or other iron oxides.

Field identification & locations

Identify in the field by its smooth, waxy texture and distinctive conchoidal (shell-like) fracture patterns. Frequently found in riverbeds, gravel pits, and coastal areas.

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

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary