sedimentary

Jasper Chert

Microcrystalline Quartz (SiO2) with iron oxide inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Reddish-brown to tan. Luster: Dull to waxy. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.6-2.9.

Hardness: 6
Color: Reddish-brown to tan
Luster: Dull to waxy

Identified July 6, 2026More sedimentary →

Explore Jasper Chert 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: Reddish-brown to tan. Luster: Dull to waxy. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.6-2.9.

Formation & geological history

Formed from the accumulation of silica-rich micro-organisms or chemical precipitation in marine environments, subsequently enriched with iron oxides. These often occur as nodules within limestone or as river-tumbled pebbles.

Uses & applications

Commonly used for lapidary work (cabs), tumbled stones, and historically for primitive tools like scrapers and arrowheads due to its sharp fracture edge.

Geological facts

Red jasper specifically gets its color from high concentrations of iron. It has been used since antiquity for seals and amulets, and is mentioned frequently in historical and religious texts as a significant stone.

Field identification & locations

Field identification is based on its hardness (it will scratch glass), its smooth, waxy surface when wet, and its characteristic curved (conchoidal) fracture pattern. Found globally in riverbeds and ancient coastal sediments.