igneous
Puddingstone / orbicular jasper-like rock
Likely orbicular rhyolite or altered volcanic breccia, composed mainly of quartz, feldspar, and iron-bearing alteration minerals
AI-generated identification · may be incorrectHardness approximately 6–7 Mohs; mottled pink, gray, cream, and dark green-gray colors with a dull to slightly waxy luster. Rounded, fine-grained volcanic matrix surrounds pinkish orbicular or breccia-like patches; cleavage is not evident.
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Physical properties
Hardness approximately 6–7 Mohs; mottled pink, gray, cream, and dark green-gray colors with a dull to slightly waxy luster. Rounded, fine-grained volcanic matrix surrounds pinkish orbicular or breccia-like patches; cleavage is not evident.
Formation & geological history
Probably formed from silica-rich volcanic lava or volcanic fragments later altered by hydrothermal fluids, producing the rounded pink domains. Exact age cannot be determined from the photograph; such rocks commonly range from Precambrian to younger volcanic sequences.
Uses & applications
Used as a lapidary rough, tumbled stone, cabochon material, and collectible; attractive pieces may be polished for decorative objects. It has little structural or industrial value.
Geological facts
The contrasting rounded patches can resemble jasper or orbicular rhyolite, but definitive identification requires a fresh surface, thin section, or chemical testing.
Field identification & locations
Commonly found in volcanic terrains, especially in parts of the western United States, Mexico, Australia, and Madagascar. Test with a steel file or quartz, inspect a polished face, and check for silica-rich hardness and orbicular textures.
