mineral
Polished brown jasper pebble
Jasper, an opaque microcrystalline variety of chalcedony (SiO₂), colored by iron oxides
AI-generated identification · may be incorrectHardness 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 More mineral →
Explore Polished brown jasper pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
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.
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.
