sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown due to iron inclusions; Luster: Vitreous to waxy; Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown due to iron inclusions
Luster: Vitreous to waxy

Identified February 16, 2026More sedimentary →

Explore Jasper 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 from the deposition of silica-rich fluids in volcanic ash or sedimentary deposits, often during the Proterozoic to Cenozoic eras. The red coloring is typically caused by iron (III) oxidation.

Uses & applications

Commonly used in lapidary work, jewelry (cabochons), interior decoration (slabs), and historically used for making stone tools due to its conchoidal fracture.

Geological facts

The name 'Jasper' originates from the Greek word 'iaspis', meaning 'spotted stone.' It has been used for millennia by ancient civilizations, including the Minoans and Egyptians, for seals and amulets.

Field identification & locations

Identify in the field by its opaque nature (unlike translucent chalcedony), smooth conchoidal fracture patterns, and inability to be scratched by a steel knife. Frequently found in riverbeds and gravel deposits worldwide.