mineral

Yellow jasper (likely iron-stained chert)

Microcrystalline quartz, SiO₂, colored mainly by iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque yellow to ochre with brown-red patches, waxy to dull luster, and conchoidal fracture. It has no visible cleavage and is composed of cryptocrystalline quartz.

Identified September 5, 2026More mineral →

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Physical properties

Hardness about 6.5–7 Mohs; opaque yellow to ochre with brown-red patches, waxy to dull luster, and conchoidal fracture. It has no visible cleavage and is composed of cryptocrystalline quartz.

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, often incorporating limonite or goethite that produces the yellow color; commonly Paleozoic to younger, with age varying by deposit. The pictured piece appears naturally broken and weathered.

Uses & applications

Used as lapidary material for cabochons, beads, carvings, and decorative stone; too small or irregular here for significant construction use.

Geological facts

Jasper is a variety of chert distinguished by abundant impurities and strong coloration. Yellow varieties are commonly marketed as yellow jasper, but similar material may be called iron-rich chert.

Field identification & locations

Identify it by testing for quartz-like hardness: it should scratch ordinary glass and resist a steel knife, with a smooth waxy fracture. Common sources include Brazil, India, Madagascar, Australia, and the western United States.