sedimentary

Polished orbicular jasper

Siliceous microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and other mineral inclusions

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, opaque, with a waxy to vitreous luster and brown, cream, gray, and rusty-red orbicular patterns. It is cryptocrystalline quartz with no visible cleavage and conchoidal fracture; polishing produces the smooth glossy surface.

Identified September 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement sediment, volcanic material, or organic debris; orbicular patterns develop from concentric mineral growth or replacement. Its exact geological age and locality cannot be determined from the photograph.

Uses & applications

Used for cabochons, carvings, beads, polished display stones, and lapidary items; it has little industrial value compared with ordinary quartz.

Geological facts

The circular “eye” patterns are caused by contrasting chalcedony, quartz, clay, and iron-oxide zones rather than separate crystals. Similar material is sold as orbicular jasper, ocean jasper, or leopard jasper, though trade names are often locality-dependent.

Field identification & locations

Identify it by its opaque, patterned body, very fine grain, glassy polish, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Madagascar, Mexico, Australia, Brazil, and the western United States.