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Rhyolite identification and geology

A fine-grained aphanitic felsic volcanic rock with a silica content exceeding 69%, the extrusive equivalent of granite. Rhyolite is typically light-colored white, gray, pink and may have a porphyritic or flow-banded texture. Rhyolitic eruptions are often explosive due to the high viscosity and gas content of the magma, producing pyroclastic flows, ignimbrites, and ash falls rather than fluid lava flows. Field: petrology. Example: The Yellowstone volcanic system has produced three cataclysmic rhyolitic eruptions in the past 2.1 million years, each generating massive ignimbrite sheets that covered thousands of square kilometers.. Related terms: Granite, Felsic, Obsidian, Ignimbrite.

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-03-30T15:19:42.055955+00:00
Review status
Published; not independently peer-reviewed
  • USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
  • Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.

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Common questions

What does Rhyolite mean in geology?
A fine-grained aphanitic felsic volcanic rock with a silica content exceeding 69%, the extrusive equivalent of granite. Rhyolite is typically light-colored white, gray, pink and may have a porphyritic or flow-banded texture. Rhyolitic eruptions are often explosive due to the high viscosity and gas content of the magma, producing pyroclastic flows, ignimbrites, and ash falls rather than fluid lava flows.
What is an example of Rhyolite?
The Yellowstone volcanic system has produced three cataclysmic rhyolitic eruptions in the past 2.1 million years, each generating massive ignimbrite sheets that covered thousands of square kilometers.
Which earth-science field uses the term Rhyolite?
Rhyolite is used in petrology.
Which terms are related to Rhyolite?
Related terms in this reference are Granite, Felsic, Obsidian, Ignimbrite.

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