sedimentary
Ocean Jasper
Orbicular Jasper (Silicon Dioxide with impurities, SiO2)
Hardness: 6.5-7 (Mohs); Color: Red, orange, green, white, and gray with orbicular (circular) patterns; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None.
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Red, orange, green, white, and gray with orbicular (circular) patterns; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None.
Formation & geological history
Formed by the precipitation of silica around a nucleus, creating spherulitic structures. This specific variety is found in Cretaceous-age volcanic rocks (rhyolitic) along the coast of Madagascar.
Uses & applications
Primarily used for lapidary work, jewelry, ornamental carvings, and as a popular collector's mineral. It is also highly valued in metaphysical communities.
Geological facts
True Ocean Jasper is only found at a single location in northwestern Madagascar (near Marovato). It can only be mined during low tide, giving it its name. The original vein is largely exhausted, making high-quality specimens increasingly rare.
Field identification & locations
Identify by prominent 'orbicular' patterns and swirling colors within a chalcedony matrix. It lacks the banding of agate. Look for smooth, polishable surfaces and high density. Found exclusively in the Ambolobozo Peninsula, Madagascar.
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