sedimentary

Jasper with Iron Staining

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) impurities

Hardness: 6.5-7 Mohs; Color: Brown, red, and ochre with grey patches; Luster: Dull to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Brown, red, and ochre with grey patches
Luster: Dull to waxy

Identified March 23, 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. The coloration is primarily due to the oxidation of iron minerals during the petrification process, occurring across various geological ages from the Precambrian to Cenozoic.

Uses & applications

Used primarily for lapidary work, decorative cabochons, garden landscaping, and as a collector's specimen. In industry, high-purity silica stones were historically used for making primitive tools.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'jasper' means 'spotted or speckled stone,' derived from the Old French word 'jaspre'. It is often found in massive form rather than distinct crystals.

Field identification & locations

Identify in the field by its hardness (will scratch glass), opaque nature, and smooth, curved (conchoidal) surface where it has broken. Commonly found in desert regions, riverbeds, and areas of high volcanic activity.

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