Light-colored, fine-grained volcanic rock with the same composition as granite. Often shows flow banding. Texture: Aphanitic to porphyritic, often flow-banded. Rock type: Igneous Extrusive. Grain size: Fine or glassy. Minerals present: Quartz, Sanidine, Plagioclase, Biotite. Formation: Erupts from caldera-forming eruptions and rhyolitic domes. Extremely viscous, high-silica magma 69% SiO₂ . Common geological settings: Yellowstone, New Zealand, Iceland, Lipari Islands; associated with caldera systems. Common look-alikes and related entries: Dacite, Granite, Tuff.
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GeoMiner
Last updated
2026-03-30T14:38:11.327197+00:00
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Published; not independently peer-reviewed
Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
Light-colored, fine-grained volcanic rock with the same composition as granite. Often shows flow banding.
How can you identify Rhyolite?
Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Extrusive; texture: Aphanitic to porphyritic, often flow-banded; grain size: Fine or glassy; common minerals: Quartz, Sanidine, Plagioclase, Biotite. Confirm an important identification with additional field tests or qualified laboratory work.
How does Rhyolite form?
Erupts from caldera-forming eruptions and rhyolitic domes. Extremely viscous, high-silica magma 69% SiO₂ .
Where is Rhyolite commonly found?
Yellowstone, New Zealand, Iceland, Lipari Islands; associated with caldera systems.
What is Rhyolite commonly confused with?
Rhyolite may be confused with Dacite, Granite, Tuff. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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