igneous
Polished orbicular jasper
Jasper, a microcrystalline variety of quartz (SiO₂), colored by iron oxides and other accessory minerals
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque orange-red, yellow, green, and black coloration with glossy polish and swirling/orbicular patterns. It has cryptocrystalline quartz structure, no visible cleavage, conchoidal fracture, and specific gravity around 2.6.
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Physical properties
Hardness about 6.5–7 Mohs; opaque orange-red, yellow, green, and black coloration with glossy polish and swirling/orbicular patterns. It has cryptocrystalline quartz structure, no visible cleavage, conchoidal fracture, and specific gravity around 2.6.
Formation & geological history
Forms when silica-rich fluids replace or cement volcanic ash, breccia, or other sediment, with iron and manganese producing vivid colors; some orbicular varieties develop from rhythmic mineral growth. Specimens may range from Paleozoic to Cenozoic, depending on locality.
Uses & applications
Used for cabochons, carvings, beads, display stones, and lapidary art; occasionally as decorative facing material. Its main value is aesthetic and collectible rather than industrial.
Geological facts
The intense orange-red color commonly reflects hematite or goethite inclusions. “Orbicular jasper” is a lapidary trade term covering several patterned jasper types, not one single mineral species.
Field identification & locations
Identify by its opaque waxy-to-glassy surface, colorful iron-rich patterns, lack of cleavage, and ability to scratch glass. Common sources include Madagascar, Indonesia, Mexico, Oregon, and Australia; this appears polished and may be resin-coated.
