sedimentary

Chert (Green Jasper)

Microcrystalline Quartz (SiO2) with iron silicate inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Olive green to brownish-green. Luster: Dull to waxy. Structure: Microcrystalline/Cryptocrystalline. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Olive green to brownish-green
Luster: Dull to waxy

Identified July 9, 2026More sedimentary →

Explore Chert (Green 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 on Mohs scale. Color: Olive green to brownish-green. Luster: Dull to waxy. Structure: Microcrystalline/Cryptocrystalline. Cleavage: None (conchoidal fracture).

Formation & geological history

Formed from the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation in marine environments. These specimens appear to be stream-tumbled river pebbles.

Uses & applications

Used historically for tool making (lithics); currently used for lapidary work, jewelry, and as decorative gravel.

Geological facts

Green Jasper is often associated with the presence of chlorite or iron silicate minerals. It was one of the first materials used by early humans for scrapers and projectile points due to its sharp conchoidal fracture.

Field identification & locations

Identify in the field by its hardness (will scratch glass), smooth waxy texture when wet, and lack of visible grains. Common in riverbeds and ancient sedimentary basins.