sedimentary

Jasper

Jasper (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Yellow-brown, tan, and dark brown, Luster: Vitreous to dull, Crystal Structure: Trigonal (microcrystalline/cryptocrystalline quartz), Cleavage: None, Specific Gravity: 2.58-2.91

Hardness: 6

Identified June 28, 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 through the deposition of silica in sedimentary environments or by hydrothermal replacement of volcanic ash. It often contains significant impurities (up to 20%) that provide its color. Geological age varies greatly from Precambrian to Cenozoic.

Uses & applications

Used primarily for jewelry (cabochons, beads), decorative objects, and as a popular specimen for rock hounds and mineral collectors because of its polish and patterns.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek 'iaspis', meaning 'spotted stone.' It was a favorite gemstone in the ancient world, mentioned in biblical texts and valued by early civilizations in Mesopotamia and Greece.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), smooth conchoidal fracture, and opacity. Commonly found in riverbeds, desert landscapes, and volcanic deposits. This specific specimen appears to be a river-worn pebble.