sedimentary

Jasper (Red Jasper)

Silicon Dioxide (SiO₂)

Hardness: 6.5–7 on Mohs scale; Color: Red to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline trigonal; Cleavage: None; Specific Gravity: 2.58–2.91

Hardness: 6
Color: Red to brownish-red
Luster: Dull to vitreous

Identified March 21, 2026More sedimentary →

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: Red to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline trigonal; Cleavage: None; Specific Gravity: 2.58–2.91

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine sediments, often occurring in hydrothermal veins or as nodules in sedimentary rocks. The red color is caused by iron (hematite) inclusions.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and carvings. Also used in industrial applications for its hardness and historically for stone tools.

Geological facts

Red Jasper has been used since antiquity as a gemstone; it was a favorite in the ancient world for seals and talismans. It is an opaque variety of chalcedony.

Field identification & locations

Identify by its opaque nature (it does not let light through even at thin edges) and conchoidal fracture. Common in gravel beds and desert regions worldwide. High-quality specimens should have a deep, uniform color.