mineral

Polished ocean jasper tower

Orbicular chalcedony (microcrystalline quartz, SiO₂), commonly sold as ocean jasper

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; gray, white, and pale green with orbicular and banded patterns; vitreous to waxy luster, trigonal quartz structure, no visible cleavage. The pictured piece is cut and polished.

Identified September 27, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; gray, white, and pale green with orbicular and banded patterns; vitreous to waxy luster, trigonal quartz structure, no visible cleavage. The pictured piece is cut and polished.

Formation & geological history

Silica-rich fluids deposited chalcedony in volcanic cavities and fractures, later producing orbicular patterns. Ocean jasper is associated with Oligocene–Miocene volcanic rocks of Madagascar.

Uses & applications

Used for carvings, display pieces, beads, and jewelry; not generally used as a building stone.

Geological facts

“Ocean jasper” is a trade name rather than a formal mineral species; deposits near Marovato, Madagascar, are famous for its rounded patterns.

Field identification & locations

Identify by its polished, rounded orbicular markings within chalcedony; compare with other patterned jaspers, as appearance alone cannot confirm locality. Madagascar is the classic source.