sedimentary

Chert (specifically Yellow Jasper variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Yellow to brownish-yellow; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Yellow to brownish-yellow
Luster: Waxy to vitreous

Identified May 24, 2026More sedimentary →

Explore Chert (specifically Yellow Jasper variety) 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 through the accumulation of silica-rich microfossils (like radiolaria or diatoms) or by chemical precipitation in marine environments. Often found as nodules in limestone or chalk beds.

Uses & applications

Used historically for stone tools (knapping) due to its sharp conchoidal fracture. Today used in lapidary work, jewelry, and as a collector's specimen.

Geological facts

Jasper is an opaque variety of silica that gets its distinctive yellow color from traces of iron hydroxide (Goethite). It has been used by ancient civilizations for seals and ornamentation for thousands of years.

Field identification & locations

Identify in the field by its smooth, shell-like (conchoidal) fracture surfaces, its ability to scratch glass, and its waxy feel. Commonly found in riverbeds or eroded sedimentary outcrops.