sedimentary

Tumbled yellow chert or jasper pebble

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

AI-generated identification · may be incorrect

Opaque mustard-yellow, smoothly rounded and matte-to-waxy; quartz hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity around 2.6. The adjacent gray pebble may be a separate quartz-rich rock.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica replaces or cements sediment, with iron oxides producing the yellow color; commonly Paleozoic–Cenozoic but exact age cannot be determined visually. The rounded shape indicates stream or beach abrasion, possibly later tumbled by humans.

Uses & applications

Used as an ornamental stone, lapidary material, tumbled stone, and occasionally aggregate; typically unsuitable for fine jewelry unless it has attractive patterning or translucency.

Geological facts

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

Field identification & locations

Identify by its glassy/waxy feel, high hardness, opaque fine-grained texture, and inability to scratch with a steel knife easily; yellow color commonly reflects limonite or goethite. Common in gravel beds and silica-rich sedimentary formations worldwide.