sedimentary

Orbicular jasper

Orbicular jasper (microcrystalline quartz/chalcedony with iron-oxide and volcanic inclusions)

AI-generated identification · may be incorrect

Typically opaque, cream to gray, red, brown, or black, with concentric orbicules and a waxy to glassy polish; Mohs hardness 6.5–7, no cleavage, and specific gravity about 2.5–2.7. The pieces shown are polished or tumbled, revealing circular spherulitic patterns.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement volcanic material, producing concentric aggregates around nuclei; many varieties are Cenozoic or younger, though exact age depends on locality. These specimens may also be sold as ocean or leopard jasper, trade names that can overlap with rhyolitic orbicular material.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and decorative objects; generally a lapidary and collector material rather than a construction stone.

Geological facts

The orbicules are commonly composed of chalcedony, quartz, feldspar, and iron oxides. Pattern, color, and locality determine commercial names and desirability.

Field identification & locations

Identify by its very hard, opaque silica-rich body, circular “eye” patterns, and resistance to scratching by steel; common sources include Madagascar, Mexico, Oregon, Indonesia, and Australia. Exact identification requires locality or mineralogical testing.