mineral

Polished red jasper or mahogany obsidian (likely jasper)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

AI-generated identification · may be incorrect

Opaque, polished, reddish-brown to black with irregular dark patches and a vitreous-to-waxy luster; quartz hardness 6.5–7, no visible cleavage, cryptocrystalline structure, specific gravity about 2.6. The rounded shape indicates a tumbled or polished specimen.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic or sedimentary material, with iron oxides producing red-brown coloration; formation ages vary widely. A definitive distinction from mahogany obsidian requires close inspection or testing.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, and decorative objects; generally ornamental rather than industrial.

Geological facts

Jasper is a variety of chalcedony/quartz containing abundant impurities, so patterns and colors are highly variable. If translucent at thin edges and showing conchoidal fracture, it may instead be mahogany obsidian, a volcanic glass.

Field identification & locations

Commonly found in volcanic and hydrothermal regions, including Oregon, Utah, California, Mexico, Madagascar, and Australia. Jasper feels grainier and is harder than glass; obsidian shows glassy luster and scratches similarly to glass.