mineral
Orbicular jasper (likely ocean jasper)
Silica-rich microcrystalline quartz/chalcedony with orbicular mineral inclusions; mainly SiO₂
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; cream to tan matrix with rounded brown-gray orbs, opaque, waxy to dull luster, and no visible cleavage. The specimen is a small polished or naturally smoothed pebble.
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Physical properties
Hardness about 6.5–7 Mohs; cream to tan matrix with rounded brown-gray orbs, opaque, waxy to dull luster, and no visible cleavage. The specimen is a small polished or naturally smoothed pebble.
Formation & geological history
Forms when silica-rich volcanic or hydrothermal fluids replace host rock and concentrate contrasting minerals into spherical patterns, commonly in Miocene volcanic settings. The exact age and locality cannot be confirmed from the image.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, and decorative objects; it has little industrial value compared with ordinary quartz.
Geological facts
Orbicular patterns are diagnostic but can occur in several jaspers, so “ocean jasper” should be treated as a locality-based trade name unless provenance is known.
Field identification & locations
Look for concentric or radiating orbs in a hard, opaque chalcedonic stone; a steel file should barely scratch it, while glass may be scratched. Ocean jasper is famously associated with Madagascar, whereas orbicular jasper also occurs in Mexico, Australia, and elsewhere.
