sedimentary

Yellow Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow to brownish-yellow; Luster: Dull to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Mustard yellow to brownish-yellow
Luster: Dull to vitreous

Identified July 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from water into volcanic ash or sedimentary beds. The yellow color is primarily due to the presence of goethite or other iron hydroxide inclusions. It can form in various geological ages from Precambrian to recent times.

Uses & applications

Commonly used for lapidary work, jewelry (cabs/beads), decorative carvings, and as a collector's specimen. Historically used for making tools and seals.

Geological facts

Jasper is an opaque variety of chalcedony. Unlike agate, which is translucent, jasper contains enough mineral impurities to make it completely opaque. It was historically revered as a protective stone for travelers.

Field identification & locations

Identify by its hardness (cannot be scratched by a knife), opaque nature, and smooth conchoidal fracture. Often found along riverbeds or in desert environments where silica-rich fluids were once active.