sedimentary

Yellow Chert or Jasper

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Yellow, mustard, or buff; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Hardness: 6
Color: Yellow, mustard, or buff
Luster: Waxy to vitreous

Identified May 8, 2026More sedimentary →

Explore Yellow Chert or Jasper in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 Mohs; Color: Yellow, mustard, or buff; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich marine organisms or from volcanic ash precipitates in sedimentary environments. Can be billions of years old or from recent geological eras.

Uses & applications

Used historically for stone tools and arrowheads; currently used in jewelry (cabochons), as an abrasive, and by crystal collectors.

Geological facts

Chert is one of the oldest materials used by humans to make tools due to its sharp edges and hardness. Yellow varieties are often colored by the presence of iron oxides like goethite.

Field identification & locations

Identify by its waxy texture, inability to be scratched by a steel knife, and smooth, curved (conchoidal) fracture patterns. Frequently found in riverbeds and limestone deposits.