mineral

Polished brown jasper or chert

Microcrystalline quartz (SiO₂), likely jasper/chalcedony

AI-generated identification · may be incorrect

Opaque brown to gray-brown, highly polished, with subtle mottling and possible iron-oxide staining; vitreous to waxy luster. Mohs hardness 6.5–7, no cleavage, conchoidal fracture, and specific gravity about 2.6.

Identified September 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediment, commonly incorporating iron oxides that produce brown coloration. Such silica materials formed in many environments and ages, so age cannot be determined from the photograph.

Uses & applications

Used for cabochons, beads, carvings, polished specimens, and lapidary décor; generally not a major construction stone in this small polished form.

Geological facts

The specimen appears tumbled or otherwise polished, making its natural fracture and texture difficult to assess. A translucent edge or conchoidal chips would support chalcedony/chert identification.

Field identification & locations

Commonly found in volcanic terrains, sedimentary beds, and gravel deposits worldwide, including Brazil, Madagascar, the western United States, and Australia. A steel file should barely scratch it; quartz will scratch glass, though testing may damage the specimen.