mineral

Tumbled brown jasper (likely iron-rich chalcedony)

Jasper, opaque microcrystalline quartz (SiO₂), commonly colored by iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown to reddish-brown, opaque, with a waxy-to-glassy polish and no visible cleavage. Microcrystalline quartz has a cryptocrystalline trigonal structure; specific gravity is about 2.6.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or replaces volcanic and sedimentary material, with iron oxides producing the brown color. Deposits occur from many geological ages; this piece has been shaped and polished by tumbling.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and decorative objects; lower-grade jasper is also used as aggregate and ornamental stone.

Geological facts

Jasper is a variety of chert distinguished by its opacity and abundant impurities. Brown coloration may overlap with brecciated jasper, iron-rich chalcedony, or polished ironstone.

Field identification & locations

Identify by its opaque, uniformly fine texture, lack of cleavage, glassy polish, and resistance to scratching with a steel knife; quartz should not scratch readily. Common sources include Brazil, India, Madagascar, Australia, and the western United States.