sedimentary

Yellow Jasper (Chert) Pebble

Silicon Dioxide (SiO2) with Iron Oxides

Hardness: 6.5-7 on Mohs scale; Color: mustard yellow to brownish-yellow; Luster: waxy to vitreous when wet; Crystal structure: microcrystalline/cryptocrystalline quartz; Cleavage: none, displays conchoidal fracture

Hardness: 6
Color: mustard yellow to brownish-yellow
Luster: waxy to vitreous when wet

Identified July 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and microcrystalline precipitation of silica, colored by hydrated iron oxide (goethite/limonite) impurities, often rounded by natural river or beach erosion over time

Uses & applications

Used for lapidary arts, rock tumbling, decorative gravel, jewelry making, and cabochons

Geological facts

Yellow jasper gets its characteristic warm mustard color from micro-inclusions of iron oxides (such as goethite or limonite) distributed evenly throughout the dense quartz matrix. Smooth river pebbles like this have been naturally polished by water and sand friction over thousands to millions of years.

Field identification & locations

Identified by its smooth, water-worn shape, yellowish hue, opaque density, and waxy surface when wet. Commonly found along riverbeds, gravel bars, lakeshores, and alluvial deposits worldwide.

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