mineral

Polished ocean jasper (orbicular jasper)

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown-tan, opaque, waxy to vitreous luster, with reddish-brown orbicular inclusions. No visible cleavage; cryptocrystalline quartz structure; specific gravity about 2.55–2.70.

Identified August 22, 2026More mineral →

Explore Polished ocean jasper (orbicular jasper) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or replaces volcanic rock, while iron and other minerals create the orbicular patterns. Most orbicular jasper is Cenozoic volcanic material, though exact age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, and polished decorative stones; generally an inexpensive lapidary material.

Geological facts

The rounded spot patterns are mineral aggregates rather than true fossils or crystal-filled vesicles. “Ocean jasper” is a trade name, especially associated with Madagascar material.

Field identification & locations

Identify it by its polished surface, opaque brown chalcedony body, and contrasting circular iron-rich markings; jasper does not fizz in dilute acid and is too hard to scratch with steel easily. Common sources include Madagascar, Mexico, Australia, and India.