mineral
Polished brown jasper pebble
Jasper, microcrystalline quartz (SiO₂) with iron-oxide and clay impurities
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque brown, tan, cream, and reddish mottling with a dull to vitreous polish. Massive, cryptocrystalline structure; no visible cleavage and conchoidal fracture. The rounded shape indicates natural water wear or tumbling.
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Physical properties
Hardness about 6.5–7 Mohs; opaque brown, tan, cream, and reddish mottling with a dull to vitreous polish. Massive, cryptocrystalline structure; no visible cleavage and conchoidal fracture. The rounded shape indicates natural water wear or tumbling.
Formation & geological history
Jasper forms when silica-rich groundwater replaces or cements volcanic ash, sediments, or other rock, with iron oxides producing the brown-red colors. Deposits occur in many geological ages and settings worldwide.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and ornamental objects; occasionally used as a durable decorative aggregate. This appears to be a common lapidary specimen rather than gem-grade material.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, distinguished from agate by its lack of translucent banding. Color patterns commonly reflect iron-rich fluids and incorporated rock fragments.
Field identification & locations
Identify it by its opaque, patterned appearance, high hardness, and inability to scratch with a steel knife; quartz or glass should scratch it. Common sources include Brazil, India, Madagascar, Mexico, Australia, and the western United States.
