sedimentary
Ocean Jasper
Silicon dioxide with impurities (SiO2 + impurities)
Hardness: 6.5–7 on Mohs scale; Color: Dark green with white/light green inclusions (orbicular pattern); Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (Trigonal); 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: Dark green with white/light green inclusions (orbicular pattern); Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None; Specific Gravity: 2.6–2.7
Formation & geological history
Formed from the precipitation of silica in volcanic environments where mineral-rich water flows through rock cavities. This variety is specific to the coast of Madagascar, formed during the Cretaceous period.
Uses & applications
Primarily used in jewelry as cabochons, for specimen collecting, and in ornamental carvings or metaphysical practices.
Geological facts
Ocean Jasper is only found in the Marovato area of Madagascar. It is named because the original deposits could only be accessed by boat during low tide. The distinctive 'eyes' or circles are known as orbicules.
Field identification & locations
Identify by its unique orbicular (circular) patterns and variety of colors in a single stone. In the field, look for chalcedony with spherical inclusions found near the coastline of Madagascar.
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