sedimentary

Chert (Jasper)

Cryptocrystalline Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Opaque tan to brown; Luster: Dull to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.8

Hardness: 6
Color: Opaque tan to brown
Luster: Dull to waxy

Identified June 8, 2026More sedimentary →

Explore Chert (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: Opaque tan to brown; Luster: Dull to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.8

Formation & geological history

Formed from the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Often found as nodules or stream-tumbled pebbles.

Uses & applications

Historically used for tools and arrowheads; currently used for decorative lapidary work, jewelry (cabochons), and landscaping.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used since ancient times for cylinder seals and amulets due to its durability and ability to take a high polish.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel nail), smooth waxy texture, and conchoidal (shell-like) fracture edges. Commonly found in riverbeds and gravel deposits.