mineral

Tumbled brown jasper

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides

AI-generated identification · may be incorrect

Opaque to slightly translucent, chocolate-brown with rusty mottling and a glassy polish; typically Mohs hardness 6.5–7, no cleavage, cryptocrystalline structure, and specific gravity about 2.55–2.70.

Identified September 9, 2026More mineral →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or other rocks, with iron producing the brown-red coloration. Its exact geological age cannot be determined from the photograph; deposits range from Precambrian to recent.

Uses & applications

Commonly sold as inexpensive tumbled stone, cabochons, beads, carvings, and decorative objects; occasionally used as a minor ornamental stone.

Geological facts

Jasper is an opaque variety of chalcedony and is technically quartz-rich rather than a single mineral species. Brown varieties may overlap visually with iron-rich chert or brecciated jasper.

Field identification & locations

Identify by its waxy-to-glassy luster, opaque earthy patterning, lack of visible cleavage, and ability to scratch ordinary glass; it should not fizz in dilute acid. Common sources include Brazil, Madagascar, India, Mexico, and the western United States.