metamorphic
Orbicular jasper / brecciated jasper slab
Silicified volcanic rock composed mainly of microcrystalline quartz (SiO₂), with iron-oxide and possible chalcedony/agate bands
AI-generated identification · may be incorrectTypically Mohs 6.5–7, opaque to translucent in thin bands, dull to waxy luster, green-brown matrix with cream, orange, and red orbicular or brecciated patterns; no obvious cleavage and conchoidal fracture. The pale winding structures may be silica-filled fractures or orbicular growth zones.
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Physical properties
Typically Mohs 6.5–7, opaque to translucent in thin bands, dull to waxy luster, green-brown matrix with cream, orange, and red orbicular or brecciated patterns; no obvious cleavage and conchoidal fracture. The pale winding structures may be silica-filled fractures or orbicular growth zones.
Formation & geological history
Forms when silica-rich fluids replace or fill fractures in altered volcanic rock, often producing jasper, chalcedony, and iron-oxide color zones. Ages vary widely, commonly Paleozoic to Precambrian depending on locality.
Uses & applications
Used for polished slabs, cabochons, carvings, and decorative objects; attractive specimens have modest lapidary and collector value.
Geological facts
The specimen appears cut and polished, exposing contrasting silica-rich veins and rounded inclusions rather than a single crystal mineral.
Field identification & locations
Identify by its very hard, fine-grained texture, opaque jasper body, colorful chalcedony-like veins, and inability to scratch with a steel knife; localities cannot be confirmed from the image, though orbicular jasper is famous from Oregon, Mexico, Madagascar, and Australia.
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