mineral
Polished jasper pebble
Microcrystalline quartz (chalcedony), chiefly SiO₂, with iron-oxide impurities
AI-generated identification · may be incorrectTypically Mohs 6.5–7; opaque tan, brown, reddish, and cream patterns; waxy to dull luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The smooth shape indicates natural water wear or tumbling/polishing.
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Physical properties
Typically Mohs 6.5–7; opaque tan, brown, reddish, and cream patterns; waxy to dull luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The smooth shape indicates natural water wear or tumbling/polishing.
Formation & geological history
Forms when silica-rich groundwater fills cavities, fractures, or sedimentary pore spaces and incorporates iron oxides and other impurities; commonly Cenozoic to older, depending on its host formation.
Uses & applications
Used for cabochons, beads, carvings, and ornamental stones; durable jasper is also used for decorative objects and small lapidary goods.
Geological facts
Jasper is an opaque variety of chalcedony, unlike translucent agate. The irregular reddish-brown patches are typical of iron staining or brecciation, but the exact jasper variety cannot be confirmed from the image alone.
Field identification & locations
Common in volcanic and sedimentary terrains worldwide, including Oregon, California, Arizona, Madagascar, Brazil, India, and Australia. Identify by opacity, hardness, waxy appearance, and resistance to scratching by steel; acid produces no reaction.
