sedimentary

Yellow chert or jasper pebble

Microcrystalline quartz (SiO₂), likely iron-oxide-stained chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-yellow to ochre, opaque, waxy-to-dull luster, very fine-grained cryptocrystalline structure, and no visible cleavage. It appears water-worn and rounded, with a possible natural fracture or vein.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica precipitates from groundwater or replaces sediment, commonly with iron oxides producing the yellow color; likely Paleozoic–Cenozoic material, though age cannot be determined from the photograph.

Uses & applications

Used as an ornamental stone, lapidary material, cabochons, beads, and decorative aggregate; this small ordinary pebble has little commercial value.

Geological facts

Chert and jasper are varieties of microcrystalline quartz; jasper is typically more opaque and impurity-rich, while chert may be more uniformly gray, brown, or translucent.

Field identification & locations

Identify by its glassy-hard feel, inability to scratch with a steel knife, lack of fizz in dilute hydrochloric acid, and conchoidal fracture; common in stream gravels and silica-rich formations worldwide.