sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, yellow, ochre; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, yellow, ochre
Luster: Vitreous to dull

Identified April 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over millions of years, the silica crystallizes alongside impurities like iron oxide, creating the characteristic opacity and color banding.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons, beads), decorative ornaments, stone carvings, and lapidary collecting. Historically used for making tools due to its sharp fracture edges.

Geological facts

Jasper has been a favorite gemstone since ancient times. It is mentioned in the Bible and was frequently used in Babylonian cylinder seals and Minoan jewelry. Its name is derived from the Greek word 'iaspis', meaning 'spotted stone'.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth, waxy feel when water-worn. Common in riverbeds and ancient seafloor deposits worldwide.