sedimentary

Yellow jasper or chert

Microcrystalline quartz (SiO₂), likely iron-oxide stained chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-yellow to honey-brown, waxy to vitreous luster, opaque to slightly translucent, and lacking visible cleavage. The smooth conchoidal fracture and fine texture are typical of chert/jasper.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediment, commonly during diagenesis; iron oxides produce the yellow-brown color. Its precise geological age cannot be determined from the image and depends on its source formation.

Uses & applications

Used for carvings, cabochons, beads, tumbling, lapidary ornaments, and occasionally decorative stone; generally unsuitable for major construction because pieces are small.

Geological facts

Jasper is an opaque variety of chert, while more translucent material may be called yellow chalcedony. Color commonly comes from limonite or other hydrated iron oxides.

Field identification & locations

Identify by testing for quartz-level hardness— it should scratch window glass—and observing a conchoidal fracture, dense texture, and no fizz in dilute acid. Common worldwide, including sedimentary and volcanic terrains; exact locality requires provenance.