sedimentary
Ocean Jasper (Sea Jasper)
Spherulitic Chalcedony (SiO2)
Hardness: 6.5–7 on Mohs scale; Color: Multi-colored with green, cream, white, pink, and brown swirls or 'orbicular' patterns; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.7.
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Multi-colored with green, cream, white, pink, and brown swirls or 'orbicular' patterns; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.7.
Formation & geological history
Formed as a rhyolitic or volcanic tuff where silica-rich fluids cooled and crystallized in orbicular patterns over millions of years. This specific variety is found only in the coast of Madagascar, typically in intertidal zones where it must be mined at low tide.
Uses & applications
Primarily used for lapidary arts, jewelry (cabochons), interior decoration, and metaphysical/collection purposes. Its unique patterns make it highly desirable for polished specimens.
Geological facts
This rare form of jasper was rediscovered in 1999 after decades of search since it was first mentioned in 1922. Because the original veins are located along the shoreline and can only be accessed by boat at low tide, it is considered one of the more difficult semi-precious stones to extract.
Field identification & locations
Identify in the field by its distinct orbicular (eye-like) patterns and wave-like banding. It is exclusively found in the Ambolobozo peninsula of Madagascar. To test, use a hardness pick; it should scratch glass but not be scratched by a steel nail.
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