sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5–7 (Mohs scale), Color: Brownish-red to tan/ochre (due to iron oxides), Luster: Vitreous/Waxy, Crystal Structure: Microcrystalline (Trigonal), Cleavage: None, Fracture: Conchoidal.

Hardness: 6

Identified April 21, 2026More sedimentary →

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Physical properties

Hardness: 6.5–7 (Mohs scale), Color: Brownish-red to tan/ochre (due to iron oxides), Luster: Vitreous/Waxy, Crystal Structure: Microcrystalline (Trigonal), Cleavage: None, Fracture: Conchoidal.

Formation & geological history

Formed through the deposition of silica from water in sedimentary environments, or as a replacement in volcanic ash or organic materials. It is an opaque variety of chalcedony.

Uses & applications

Used primarily in lapidary work, jewelry (beads, cabochons), ornamental decoration, and as a popular specimen for collectors.

Geological facts

Jasper has been used as a gemstone since antiquity; it was mentioned in the Bible and used by ancient Minoans for seals. Its name comes from the Greek word 'iaspis', meaning 'spotted stone'.

Field identification & locations

Identify in the field by its opacity (unlike translucent agate/chalcedony), conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds and coastal regions where silica-rich rocks weather.