mineral

Polished orbicular jasper (likely ocean jasper)

Silicified microcrystalline quartz (SiO₂), commonly called orbicular jasper or ocean jasper

AI-generated identification · may be incorrect

Opaque, rounded polished stone with orange-tan, cream, gray, and black orbicular/patchy patterns; dull to waxy luster, no visible cleavage, Mohs hardness about 6.5–7, and specific gravity roughly 2.5–2.7. The orange areas may reflect iron oxides, while dark zones are likely manganese or other inclusions.

Identified September 21, 2026More mineral →

Explore Polished orbicular jasper (likely ocean 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 volcanic or hydrothermal fluids replace and cement volcanic material, producing jasper and orbicules; ocean jasper is chiefly associated with Oligocene–Miocene volcanic rocks of Madagascar. Exact identification is uncertain from one photograph.

Uses & applications

Used for cabochons, tumbled stones, carvings, beads, and decorative objects; valued primarily as an ornamental gemstone rather than for industrial construction.

Geological facts

Jasper is a variety of chalcedony/microcrystalline quartz, though orbicular varieties may contain mixed silica phases and altered volcanic minerals.

Field identification & locations

Field clues include hardness sufficient to scratch glass, opaque fine-grained texture, and resistance to acid; it should not show obvious individual quartz crystals. Comparable orbicular jasper occurs in Madagascar, Mexico, Australia, and the western United States.