mineral

Polished brown stone, likely jasper or chert

Microcrystalline quartz (SiO₂), probable jasper/chert; identification is limited by the image

AI-generated identification · may be incorrect

Opaque dark brown, smooth and highly polished with a dull-to-waxy luster; likely hardness 6.5–7 Mohs, no visible cleavage, and conchoidal-fracture behavior. The shape appears tumbled or carved rather than naturally crystal-faced.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

Jasper and chert form when silica-rich groundwater replaces or cements sediment, commonly in marine or volcanic environments; ages range from Precambrian to recent. Polishing and shaping are human processing.

Uses & applications

Used as ornamental stone, cabochons, carvings, worry stones, and small collectibles; rarely used architecturally. It has modest decorative value unless pattern, provenance, or unusual color is exceptional.

Geological facts

A steel file generally does not scratch quartz-rich jasper, while glass can be scratched by it. Brown coloration commonly comes from iron oxides or hydroxides.

Field identification & locations

Look for opaque color, waxy luster, very fine texture, and conchoidal edges; a streak test is usually white to pale brown. Common sources include the western United States, Brazil, India, Madagascar, and Australia.