sedimentary

Yellow Jasper

Silicon Dioxide (SiO2) with iron hydroxides

Hardness: 6.5-7 (Mohs); Color: Mustard yellow, ochre, or earthy brown; Luster: Dull or waxy when unpolished; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Mustard yellow, ochre, or earthy brown
Luster: Dull or waxy when unpolished

Identified July 19, 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, where mineral impurities like goethite or limonite provide the yellow hue. Most jasper dates to various periods from the Precambrian to more recent sedimentary accumulations.

Uses & applications

Commonly used as a decorative gemstone, in lapidary work for cabochons and beads, and as an ornamental stone in antiquity.

Geological facts

Jasper is an opaque variety of chalcedony. In ancient times, yellow jasper was often associated with sun deities and was used as a protective talisman for travelers.

Field identification & locations

Identify in the field by its opacity (even on thin edges), smooth water-worn texture, and resistance to scratches from steel. Commonly found in river beds, beaches, and desert areas where silica-rich rocks have weathered.

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