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Greenschist identification and geology

A metamorphic rock of low to intermediate grade characterized by the presence of green minerals such as chlorite, epidote, and actinolite, formed under conditions of approximately 300–500°C and moderate pressure. Greenschist facies metamorphism is a specific set of pressure-temperature conditions defined by the mineral assemblages that form in mafic rocks. The green color comes predominantly from chlorite and actinolite. Field: petrology. Example: Mafic volcanic rocks in the Abitibi greenstone belt of Ontario have been metamorphosed to greenschist facies, producing a characteristic assemblage of chlorite-actinolite-epidote-albite that gives the belt its green color and name.. Related terms: Metamorphic facies, Chlorite, Actinolite, Amphibolite.

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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 Greenschist mean in geology?
A metamorphic rock of low to intermediate grade characterized by the presence of green minerals such as chlorite, epidote, and actinolite, formed under conditions of approximately 300–500°C and moderate pressure. Greenschist facies metamorphism is a specific set of pressure-temperature conditions defined by the mineral assemblages that form in mafic rocks. The green color comes predominantly from chlorite and actinolite.
What is an example of Greenschist?
Mafic volcanic rocks in the Abitibi greenstone belt of Ontario have been metamorphosed to greenschist facies, producing a characteristic assemblage of chlorite-actinolite-epidote-albite that gives the belt its green color and name.
Which earth-science field uses the term Greenschist?
Greenschist is used in petrology.
Which terms are related to Greenschist?
Related terms in this reference are Metamorphic facies, Chlorite, Actinolite, Amphibolite.

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