sedimentary

Yellow Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Hardness: 6.5-7 Mohs scale. Color: Mustard yellow, golden brown, reddish accents. Luster: Dull to earthy in raw form, waxy to sub-vitreous when lapidary processed. Crystal Structure: Microcrystalline trigonal (cryptocrystalline quartz). Fracture: Conchoidal.

Hardness: 6
Color: Mustard yellow, golden brown, reddish accents

Identified July 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich fluids precipitate in sedimentary environments, volcanic ash layers, or hydrothermal veins, incorporating hydrous iron oxides (limonite or goethite) that impart the yellow coloration.

Uses & applications

Popular for lapidary work, cabochon cutting, tumbling, ornamental carvings, and gemstone collecting. Historically used for tool making due to its conchoidal fracture.

Geological facts

Jasper has been used since ancient times for seals, amulets, and decorative items. The yellow variety gains its distinct golden color from trace amounts of goethite or limonite within the dense quartz matrix.

Field identification & locations

Look for a opaque, fine-grained, smooth-textured stone that cannot be scratched by a steel pocketknife (hardness ~6.5). Frequently found in riverbeds, glacial deposits, and sedimentary rock formations worldwide, particularly in the western United States, Madagascar, and Brazil.

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