sedimentary

Polished ocean jasper (orbicular jasper)

Microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; creamy orange-yellow body with dark brown orbicular or dendritic inclusions, waxy to vitreous luster, and no visible cleavage. It is a polished, rounded specimen, likely with cryptocrystalline quartz structure.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic ash, sediment, or breccia; orbicular patterns develop from concentric mineral growth and alteration. Ocean jasper is principally associated with Oligocene–Miocene volcanic rocks of Madagascar, though visually similar jasper occurs worldwide.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and decorative objects; it has little industrial value because of its attractive patterns rather than rarity.

Geological facts

The pictured stone is consistent with ocean jasper or a similar orbicular jasper, but exact identification requires locality or testing. Its opaque appearance distinguishes it from translucent agate.

Field identification & locations

Identify by its opacity, fine-grained texture, rounded color patterns, and quartz-like hardness; a steel file generally does not scratch it, while quartz can scratch glass. Common sources include Madagascar, Mexico, Brazil, and the western United States.