sedimentary

Polished brown jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored by iron oxides and other impurities

AI-generated identification · may be incorrect

Typically hardness 6.5–7 Mohs, opaque brown to reddish-brown, with a glassy-to-waxy luster after polishing; microcrystalline quartz has no visible cleavage and conchoidal fracture. The rounded shape indicates tumbling or polishing.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms mainly by silicification of volcanic ash, sediment, or hydrothermal material, commonly during the Precambrian through younger geologic periods. Iron-bearing fluids produce the brown coloration.

Uses & applications

Used as ornamental stone, cabochons, beads, carvings, and tumbled specimens; occasionally used for small decorative objects. Common pieces generally have modest commercial value.

Geological facts

Jasper is a variety of chert distinguished by its opacity and abundant impurities. Brown material may be sold under locality or trade names such as picture jasper, mookaite, or chocolate jasper, though appearance alone cannot confirm a specific variety.

Field identification & locations

Commonly found in volcanic and sedimentary terrains worldwide, including India, Madagascar, Brazil, Australia, and the western United States. A glassy polish, opacity, conchoidal fracture, and hardness that can scratch window glass support identification; exact locality requires testing or provenance.