Ocean jasper is a trade name for a multicolored, patterned variety of chalcedony (microcrystalline quartz, SiO₂) found only along the coast of Madagascar. These polished spheres display orbicular (circular) patterns, banding, and color zones in shades of green, white, yellow, pink, or brown, created by rhythmic silica deposition and mineral impurities during formation.
Features:
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Composition: Composed primarily of silicon dioxide, ocean jasper is a type of chalcedony with inclusions and impurities that form complex, orb-like and banded patterns.
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Appearance: Known for its distinctive orbicular formations, concentric banding, and wide range of natural colors, often in striking combinations.
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Formation: Forms in silica-rich volcanic rock through repeated mineral deposition in gas cavities or fractures. The spherical patterns result from rhythmic crystallization over time.
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Geologic Source: Found exclusively in coastal areas of northwestern Madagascar, where deposits are often visible only at low tide.
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Educational Value: Useful for illustrating microcrystalline quartz structure, mineral zoning, and the role of volcanic activity in mineral formation.
These spheres highlight the intersection of natural chemistry and geologic time, making them ideal for collectors, educators, or display.
