sedimentary

Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, yellow, or earthy tones; Luster: Dull to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, yellow, or earthy tones
Luster: Dull to greasy

Identified June 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via the deposition of silica from water or as a replacement of organic material and limestone. Often associated with volcanic activity or ancient seabed deposits where iron oxides provide the red and brown coloration.

Uses & applications

Primarily used in jewelry making (cabochons), lapidary art, and ornamentation. Historically used for making tools and seals.

Geological facts

Jasper was one of the stones used in the Breastplate of Aaron. The name is derived from the Greek 'iaspis', meaning spotted stone. It is a dense, opaque variety of chalcedony.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), opaque nature, and smooth, waxy feel when wet. Commonly found in riverbeds, deserts, and gravel pits everywhere but notably in the Western USA, Brazil, and India.