sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Opaque reddish-brown due to iron impurities. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None, conchoidal fracture. Specific gravity: 2.58-2.91.

Hardness: 6
Color: Opaque reddish-brown due to iron impurities
Luster: Dull to vitreous

Identified June 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica into fine-grained sediments or volcanic ash. It often occurs as nodules or in veins within iron-rich or volcanic environments through chemical precipitation.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons), interior decoration, and as a collectible gemstone. Historically used for making tools and seals.

Geological facts

Jasper is an impure variety of silica. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It was one of the stones used in the Breastplate of Aaron in biblical times.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth, waxy surface when polished. Found in riverbeds, deserts, and volcanic regions globally.