sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Variegated blue-grey with yellow/brown orbicular patterns; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: Fractures conchoidally.

Hardness: 6
Color: Variegated blue-grey with yellow/brown orbicular patterns
Luster: Vitreous to waxy

Identified April 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich fluids in cavities or volcanic ash layers, often involving the replacement of organic materials or the inclusion of mineral impurities that create the patterned appearance.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and ornamental carvings. It is popular in the metaphysical and gemstone collecting communities.

Geological facts

Jasper is an opaque variety of chalcedony. The orbicular or 'eye' patterns seen in some specimens like this one are often caused by radial growth of minerals like quartz or feldspar within the silica matrix.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), its smooth conchoidal fracture, and its opacity. It is commonly found in riverbeds, or as nodules in volcanic rock and sedimentary deposits worldwide.