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Dacite identification and geology

An intermediate to felsic volcanic rock with a silica content of approximately 63–69% by weight, typically light gray with a porphyritic texture containing plagioclase, quartz, and biotite or hornblende phenocrysts. Dacite is the extrusive equivalent of granodiorite and is commonly associated with explosive eruptions at continental volcanic arcs. It occupies the compositional range between andesite and rhyolite. Field: petrology. Example: The 1980 eruption of Mount St. Helens produced a dacite dome in the crater, and dacitic pyroclastic flows devastated over 600 km² of surrounding forest.. Related terms: Granodiorite, Andesite, Rhyolite, Porphyritic.

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
2026-03-30T15:19:41.999576+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 Dacite mean in geology?
An intermediate to felsic volcanic rock with a silica content of approximately 63–69% by weight, typically light gray with a porphyritic texture containing plagioclase, quartz, and biotite or hornblende phenocrysts. Dacite is the extrusive equivalent of granodiorite and is commonly associated with explosive eruptions at continental volcanic arcs. It occupies the compositional range between andesite and rhyolite.
What is an example of Dacite?
The 1980 eruption of Mount St. Helens produced a dacite dome in the crater, and dacitic pyroclastic flows devastated over 600 km² of surrounding forest.
Which earth-science field uses the term Dacite?
Dacite is used in petrology.
Which terms are related to Dacite?
Related terms in this reference are Granodiorite, Andesite, Rhyolite, Porphyritic.

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