metamorphic
Polished brecciated jasper (likely ocean jasper or orbicular jasper)
Microcrystalline quartz/chalcedony (SiO₂) with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, irregularly mottled gray, lavender, pink, and brown; typically vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The polished surface and rounded shape indicate a tumbled or cut specimen.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, irregularly mottled gray, lavender, pink, and brown; typically vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The polished surface and rounded shape indicate a tumbled or cut specimen.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic and sedimentary material, with brecciation and iron/mineral staining producing the patches. Specific geological age depends on locality; ocean jasper is chiefly associated with Cenozoic volcanic rocks of Madagascar.
Uses & applications
Used for cabochons, beads, carvings, ornamental objects, and lapidary collections; it has little industrial value compared with common quartz aggregate.
Geological facts
The distinctive patterns result from contrasting chalcedony, quartz, iron oxides, and altered rock fragments rather than separate large crystals.
Field identification & locations
Identify it by its opaque patterned body, quartz-like hardness, lack of cleavage, and ability to scratch glass; jasper commonly occurs in volcanic terrains and silica-rich veins. Exact variety and locality require closer examination or testing.
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