mineral

Tumbled ocean jasper / orbicular jasper (probable)

Microcrystalline quartz (SiO₂), commonly with chalcedony and iron-rich inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; blue-gray, cream, and rusty-brown coloration with a fine-grained, waxy to vitreous luster. It has cryptocrystalline quartz structure, no visible cleavage, and typically conchoidal fracture; the surface is polished and rounded by tumbling.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids fill cavities or replace volcanic rock, with iron oxides producing brown-red patches; many ocean jasper varieties formed in Miocene volcanic environments of Madagascar. Exact identification and age require testing or provenance.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and decorative objects; common tumbled pieces have modest commercial value.

Geological facts

The specimen appears to show brecciated or orbicular patterning, but the visible texture is insufficient to distinguish ocean jasper from other jasper or chalcedony varieties confidently.

Field identification & locations

Identify by its opaque-to-translucent microcrystalline texture, hardness, lack of cleavage, and resistance to scratching by steel; a quartz scratch test, magnification, and locality information would help. Common sources include Madagascar, Mexico, Brazil, and the western United States.