sedimentary

Orbicular Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5-7 (Mohs scale); Color: green, red, brown, tan; Luster: Vitreous to waxy (when polished); Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: green, red, brown, tan
Luster: Vitreous to waxy (when polished)

Identified July 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic rock cavities or sedimentary layers. The circular 'orb' patterns result from radial growth of needle-like crystals around a central nucleus during the cooling or precipitation process.

Uses & applications

Primarily used for lapidary work, jewelry (cabochons), interior decoration, and as a collector's specimen.

Geological facts

Also known as 'Ocean Jasper' in certain Madagascar varieties or 'Poppy Jasper' when the colors are predominantly red. The circular patterns are scientifically known as spherulites.

Field identification & locations

Identify in the field by its distinct circular bands of color and extreme hardness (will scratch glass). Common in areas with ancient volcanic activity such as Madagascar, South Africa, or the Western US.

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Cone-in-cone structure (Secondary Sedimentary Structure)

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Chert Breccia

Brecciated Chert (Microcrystalline Silica)

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Sandstone

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