sedimentary
Ocean Jasper
Spherulitic Chalcedony (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Polychromatic circles or 'eyes' in shades of green, brown, pink, and white; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.60-2.65.
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Polychromatic circles or 'eyes' in shades of green, brown, pink, and white; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.60-2.65.
Formation & geological history
Formed by the precipitation of silica in rhythmic bands or spherules within volcanic rock cavities. Specifically found in rhythmically deposited sedimentary-like layers within the shorelines of Madagascar.
Uses & applications
Predominantly used for lapidary arts, jewelry, meditation stones, and decorative sculptures such as the 'flame' carving shown in the image.
Geological facts
Ocean Jasper is only found in one location worldwide: the coast of Madagascar. It can only be mined during low tide, earning it its aquatic name. It is technically a variety of chalcedony rather than a true jasper.
Field identification & locations
Identify by its distinctive orbicular (circular) patterns and 'flower' like inclusions. In the field, look for opaque volcanic rocks with multicolored circles. Collectors should look for high color contrast and well-defined 'eyes'.
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