mineral

Polished brown jasper pebble

Jasper, an opaque microcrystalline variety of chalcedony (SiO₂), colored by iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, tan, and reddish coloration with earthy iron staining, waxy to dull luster, and no visible crystal cleavage. It appears water-worn and polished, with small natural cavities or inclusions.

Identified September 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills or replaces sediments and volcanic cavities, incorporating iron oxides; most specimens formed during the Cenozoic or older, depending on locality. This piece was subsequently rounded by erosion and polished by humans.

Uses & applications

Used for tumbled stones, cabochons, carvings, beads, and decorative objects; durable jasper is also used for ornamental stone and lapidary work.

Geological facts

Jasper is an opaque form of chalcedony rather than a single chemically pure mineral. Brown varieties are commonly called picture jasper, coffee jasper, or simply brown jasper, though exact trade names require locality information.

Field identification & locations

Identify it by its opaque appearance, fine grain, glass-scratching hardness, and lack of cleavage; it commonly occurs in volcanic terrains, sedimentary silica deposits, and gravel beds worldwide. Exact identification is difficult from a photograph alone.