sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Red, brown, and yellow; Luster: Dull to waxy when raw, vitreous when wet/polished; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Red, brown, and yellow
Luster: Dull to waxy when raw, vitreous when wet/polished

Identified April 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic rocks, sedimentary environments, or petrified wood. It is an opaque variety of chalcedony where the color is derived from mineral impurities like iron oxides (hematite for reds, goethite for yellows).

Uses & applications

Widely used in jewelry (cabochons, beads), lapidary arts, ornamental carvings, and historically used for stone tools and seals.

Geological facts

Jasper has been used by humans for millennia; it was a favorite gem in the ancient world, mentioned in biblical texts and used by Minoan civilizations for seals. Its name comes from the Greek word 'iaspis', meaning 'spotted stone'.

Field identification & locations

Identify by its opacity (it does not transmit light even on thin edges), its smooth conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds, deserts, and volcanic regions globally, including Oregon (USA), India, and Brazil.