Sedimentary Rock

Ocean Jasper (Orbicular Jasper)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Highly variable, often green, red, yellow, brown, white, or gray, with characteristic orbicular (spherical) patterns. Luster: Dull to vitreous. Crystal Structure: Trigonal (microcrystalline quartz). Cleavage: None (fractures conchoidally). Specific Gravity: 2.58-2.91.

Hardness: 6
Luster: Dull to vitreous

Identified November 1, 2025More sedimentary rock →

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Physical properties

Formation & geological history

Ocean Jasper is a variety of jasper that forms from the deposition of silica-rich sediments, often in volcanic or hydrothermal environments. Its distinctive orbicular patterns are thought to result from spherulitic growth of chalcedony and quartz around a central nucleus, or from the successive deposition of minerals in concentric layers around a core. The exact mechanism for these orbicular patterns is still debated among geologists. It is exclusively found along the rocky coast of Madagascar and is believed to have formed in ancient lava flows or tuffs.

Uses & applications

Predominantly used in jewelry, cabochons, carved ornaments, and decorative items due to its unique and striking patterns. It is also collected by mineral enthusiasts.

Geological facts

Ocean Jasper was first publicly described in 1999, though it was known locally in Madagascar earlier. Its name comes from the fact that its deposits are found along the coastline, and it can only be mined during low tide, when the veins are exposed. It is also sometimes called 'Atlantis Stone' or 'Sea Jasper'. There are several different mining sites, each producing slightly different color variations and patterns.

Field identification & locations

In the field, Ocean Jasper is identified by its distinctive orbicular patterns, often in a diverse range of colors. Its hardness (able to scratch glass) helps distinguish it from softer minerals. It is exclusively found in Madagascar, specifically along the northwest coast. Collectors look for vibrant colors, well-defined orbs, and interesting patterns. As beads, like those pictured, they are easily recognized by the eye-like formations. Be aware of fakes, as highly patterned chalcedonies can sometimes be misrepresented.

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