igneous
Ocellar Rhyolite
Rhyolite (featuring orbicular/ocellar quartz and feldspar textures)
Hardness: 6-7 on Mohs scale; Color: brownish-green matrix with white to blue-ish circular inclusions (ocelli); Luster: dull to waxy; Texture: aphanitic to porphyritic; Crystal structure: Trigonal/Monoclinic constituents.
- Hardness
- 6-7 on Mohs scale
- Luster
- dull to waxy
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Physical properties
Hardness: 6-7 on Mohs scale; Color: brownish-green matrix with white to blue-ish circular inclusions (ocelli); Luster: dull to waxy; Texture: aphanitic to porphyritic; Crystal structure: Trigonal/Monoclinic constituents.
Formation & geological history
Formed from silica-rich volcanic lava that cooled rapidly. The 'spots' or ocelli often represent areas of liquid immiscibility or secondary mineral growth (like quartz or chalcedony) filling vesicles in the volcanic matrix. Likely dated to various volcanic eras from the Precambrian to Cenozoic.
Uses & applications
Used primarily as decorative stones, lapidary material for cabochons, and as collectibles for geological interest. Sometimes used in construction as crushed stone.
Geological facts
Similar textures are sometimes called 'Bird\'s Eye Rhyolite' or 'Rainforest Jasper' when including green hues. These patterns are created by the complex interaction of cooling magma and escaping gases.
Field identification & locations
Identify by looking for distinct circular or 'eye-like' mineral clusters embedded in a fine-grained volcanic matrix. Commonly found in volcanic regions like the American Southwest, Oregon, or Australia. Collectors should look for high contrast between the spots and the host rock.
