sedimentary

Yellow Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5-7 (Mohs scale); Color: Opaque mustard yellow to brownish-yellow; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None; Specific gravity: 2.58–2.91

Hardness: 6
Color: Opaque mustard yellow to brownish-yellow
Luster: Vitreous to dull

Identified March 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed typically in sedimentary environments when silica-rich fluids permeate through volcanic ash or mud, gradually precipitating quartz over millions of years. The yellow color is due to high iron hydroxide (goethite/limonite) content.

Uses & applications

Commonly used in jewelry (cabochons, pendants), decorative carvings, and as a popular choice for lapidary work due to its ability to take a high polish.

Geological facts

Jasper is a variety of chalcedony. In ancient times, yellow jasper was often associated with protection during travel and was believed to harbor the power of the sun. Unlike most translucent agates, jasper is defined by its opacity.

Field identification & locations

Identify in the field by its smooth, conchoidal fracture, high hardness (cannot be scratched by a steel knife), and opaque appearance. Frequently found in riverbeds and coastal regions of South Africa, Brazil, and the USA.

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