sedimentary

Yellow-brown chert (possible jasper)

Microcrystalline quartz, SiO₂; iron-oxide-stained chert

AI-generated identification · may be incorrect

Opaque, ochre-yellow to brown, with a dull to waxy luster and no visible crystals; quartz hardness is about 7 Mohs, with conchoidal fracture and no cleavage. The image alone cannot confirm whether this is jasper, a colored variety of chert.

Identified October 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica precipitates or accumulates in sediment and later becomes microcrystalline quartz; iron oxides can create yellow-brown coloration. It occurs in rocks of many ages.

Uses & applications

Chert is used for tools and sometimes as decorative stone; jasper-quality material is cut or polished for jewelry and collecting.

Geological facts

Chert and jasper are closely related silica-rich materials; jasper is typically opaque and colored by impurities.

Field identification & locations

The rounded, opaque, silica-rich appearance is consistent with chert, but identification would benefit from a hardness or streak test. Chert occurs worldwide in sedimentary formations; avoid destructive tests on a valuable specimen.