mineral
Polished brecciated jasper (likely ocean jasper or orbicular jasper)
Silica-rich chalcedony/microcrystalline quartz (SiO₂), with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, waxy to dull luster, gray-green, cream, yellow, and orange zones with rounded dark orbicular patterns. Microcrystalline quartz has no visible cleavage and conchoidal fracture; density is roughly 2.5–2.7.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, waxy to dull luster, gray-green, cream, yellow, and orange zones with rounded dark orbicular patterns. Microcrystalline quartz has no visible cleavage and conchoidal fracture; density is roughly 2.5–2.7.
Formation & geological history
Forms when silica-rich fluids replace or cement volcanic rock, producing brecciation, orbicules, and iron-oxide staining; commonly associated with Cenozoic volcanic environments. The exact variety cannot be confirmed from the image alone.
Uses & applications
Used for cabochons, carvings, slabs, and collector specimens; occasionally decorative stone, but generally unsuitable for major construction aggregate.
Geological facts
Orbicular patterns are caused by concentric mineral growth or altered volcanic fragments, not true fossil structures. Orange coloration typically reflects hematite or limonite.
Field identification & locations
Identify by its hardness, opaque waxy appearance, multicolored silica matrix, and resistance to scratching by steel; quartz or a glass tile can test it more reliably. Common sources include Madagascar, Oregon, Mexico, and Australia.
