sedimentary

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs scale; Color: Dull yellow to brownish with iron oxide streaks; Luster: Waxy to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture)

Hardness: 7 Mohs scale
Color: Dull yellow to brownish with iron oxide streaks
Luster: Waxy to dull

Identified June 21, 2026More sedimentary →

Explore Chert (Yellow 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: 7 Mohs scale; Color: Dull yellow to brownish with iron oxide streaks; Luster: Waxy to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture)

Formation & geological history

Formed via the accumulation of silica-rich microfossils or chemical precipitation in marine or groundwater environments. It is a dense, hard sedimentary rock often found in nodules or bedded layers.

Uses & applications

Used historically for stone tools due to its sharp edges when fractured. Currently used for lapidary work, jewelry (tumbled stones), and as an abrasive or decorative landscaping material.

Geological facts

Yellow jasper is specifically chert colored by goethite or other iron oxides. It has been used by humans for hundreds of thousands of years to create projectile points and scrapers.

Field identification & locations

Identify in the field by its hardness (will scratch glass), waxy feel, and characteristic conchoidal (shell-like) fracture patterns. Frequently found in riverbeds or coastal areas.