sedimentary

Iron-rich chert or weathered jasper pebble

Microcrystalline quartz (SiO₂), likely ferruginous chert/jasper

AI-generated identification · may be incorrect

Opaque brown, ochre, and reddish surface with a dull to subtly waxy luster and rounded, water-worn shape. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, conchoidal fracture expected, and typical specific gravity is approximately 2.6.

Identified September 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica replaced or cemented fine sediment, with iron oxides producing the brown-yellow coloration; later weathering and stream transport rounded it. The precise geological age cannot be determined from the photograph.

Uses & applications

Used as aggregate, road stone, carving material, and occasionally as a low-grade lapidary stone; attractive patterned pieces may be polished for display.

Geological facts

The yellow-brown banding and rusty tones commonly reflect limonite/goethite or hematite staining. A fresh broken surface would help distinguish chert from iron-rich volcanic rock or ordinary sandstone.

Field identification & locations

Common in stream gravels and weathered sedimentary terrains worldwide. Test with a steel file or glass: genuine chert generally scratches glass, while a streak test and close examination of fracture texture are useful; definitive identification requires hardness and thin-section or chemical testing.