metamorphic
Polished orbicular jasper
Jasper, a microcrystalline variety of quartz (SiO₂), with iron-oxide and volcanic/mineral inclusions
AI-generated identification · may be incorrectOpaque orange, cream, brown, and dark green stone with a waxy to dull luster and orbicular patterning; hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity around 2.5–2.7.
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Physical properties
Opaque orange, cream, brown, and dark green stone with a waxy to dull luster and orbicular patterning; hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity around 2.5–2.7.
Formation & geological history
Forms when silica-rich fluids replace or cement volcanic ash, often preserving rounded spherulites and iron-rich inclusions; deposits are generally Precambrian to younger, depending on locality.
Uses & applications
Used for cabochons, beads, carvings, polished specimens, and decorative stone; not generally used as structural construction material.
Geological facts
The orange coloration commonly comes from hematite or goethite, while green areas may reflect chlorite or other altered volcanic minerals. Orbicular jasper is sometimes marketed under locality names such as ocean jasper, but appearance alone cannot confirm a specific variety.
Field identification & locations
Identify it by its opaque fine-grained texture, high polish, colorful iron-rich patterns, and lack of glassy translucence; common sources include Madagascar, Australia, Mexico, and the western United States. A locality label or testing is needed for precise identification.
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