mineral

Polished brown chalcedony or jasper

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

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, honey, orange, and cream coloration with a resinous to waxy luster. The specimen appears tumbled/polished, opaque to slightly translucent, and lacks visible cleavage; its exact texture is obscured by the finish.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures, with iron oxides producing the brown-orange colors. Chalcedony and jasper commonly formed in volcanic rocks during the Cenozoic and older geologic periods.

Uses & applications

Used as ornamental stone, cabochons, beads, carvings, and inexpensive collector specimens. Typical value is modest unless it has unusually attractive patterning or provenance.

Geological facts

The image does not show diagnostic banding or crystal faces, so a precise identification is not possible; brown agate, jasper, iron-stained quartz, and even petrified wood are alternatives.

Field identification & locations

Likely regional possibilities near 38.7°N, 121.3°W include river-worn jasper, chalcedony, and quartz-bearing material from Sierra Nevada-derived gravels. Check for glassy conchoidal fracture, translucency at edges, and hardness sufficient to scratch ordinary glass; a streak, specific gravity, and close inspection of patterning would help distinguish jasper from agate or petrified wood.