Rock Identifier
Ocean Jasper (Spherulitic Chalcedony (SiO2 with impurities)) — mineral
mineral

Ocean Jasper

Spherulitic Chalcedony (SiO2 with impurities)

Hardness: 6.5-7 (Mohs); Color: Multi-colored with orbicular patterns; Luster: Vitreous to waxy; Structure: Microcrystalline (trigonal); Cleavage: None; Specific Gravity: 2.6-2.65

Hardness
6
Color
Multi-colored with orbicular patterns
Luster
Vitreous to waxy
Identified More mineral
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Physical properties

Hardness: 6.5-7 (Mohs); Color: Multi-colored with orbicular patterns; Luster: Vitreous to waxy; Structure: Microcrystalline (trigonal); Cleavage: None; Specific Gravity: 2.6-2.65

Formation & geological history

A rare variety of jasper/chalcedony formed through the volcanic silicification of rhyolite flows. It typically features orbicular (eye-like) patterns formed by radial crystallization of quartz and feldspar. The most famous deposits are found at the edge of the Indian Ocean in Madagascar.

Uses & applications

Primarily used for ornamental purposes, lapidary art, jewelry, and as a popular collector's specimen due to its unique aesthetic patterns.

Geological facts

Ocean Jasper is exclusively found on the coast of Madagascar. Some original veins were only accessible by boat at low tide, leading to its name and reputation for rarity once specific deposits were depleted.

Field identification & locations

Identify by its characteristic 'orbs' or circles of color and high polish. In the field, look for volcanic coastal outcrops in northwestern Madagascar. Collectors value specimens with high contrast, vibrant colors, and complete orbs.