mineral
Polished banded jasper
Microcrystalline quartz (SiO₂), commonly with iron-oxide and clay-mineral bands
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque brown, gold, black, and cream swirls; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The specimen appears tumbled or polished.
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Physical properties
Hardness about 6.5–7 Mohs; opaque brown, gold, black, and cream swirls; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The specimen appears tumbled or polished.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or brecciated rock, with iron oxides producing the contrasting colors. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Used for cabochons, carvings, lapidary ornaments, paperweights, and decorative stone; attractive patterned pieces have modest collector value.
Geological facts
The flowing bands may resemble wood grain or landscape imagery, a common reason jasper varieties are collected. Jasper is an aggregate rather than a single well-formed crystal.
Field identification & locations
Identify it by its opaque appearance, strong swirling bands, glassy/waxy polish, and resistance to scratching by ordinary steel. Common sources include Oregon, Idaho, Utah, Arizona, Madagascar, Australia, and South Africa.
