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Epidote identification and geology

A calcium-aluminum-iron silicate mineral Ca₂ Al,Fe³⁺ ₃ SiO₄ ₃ OH with a distinctive pistachio-green to yellowish-green color, monoclinic crystal system, and a Mohs hardness of 6–7. Epidote is a common metamorphic mineral found in greenschist facies rocks and is also produced by hydrothermal alteration of plagioclase and other calcium-bearing minerals. It is an important indicator mineral for certain metamorphic conditions. Field: mineralogy. Example: Epidote imparts a characteristic pistachio-green color to hydrothermally altered volcanic rocks in the propylitic alteration zone surrounding many porphyry copper deposits.. Related terms: Greenschist, Chlorite, Actinolite, Metamorphism.

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
2026-03-30T15:19:42.127987+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 Epidote mean in geology?
A calcium-aluminum-iron silicate mineral Ca₂ Al,Fe³⁺ ₃ SiO₄ ₃ OH with a distinctive pistachio-green to yellowish-green color, monoclinic crystal system, and a Mohs hardness of 6–7. Epidote is a common metamorphic mineral found in greenschist facies rocks and is also produced by hydrothermal alteration of plagioclase and other calcium-bearing minerals. It is an important indicator mineral for certain metamorphic conditions.
What is an example of Epidote?
Epidote imparts a characteristic pistachio-green color to hydrothermally altered volcanic rocks in the propylitic alteration zone surrounding many porphyry copper deposits.
Which earth-science field uses the term Epidote?
Epidote is used in mineralogy.
Which terms are related to Epidote?
Related terms in this reference are Greenschist, Chlorite, Actinolite, Metamorphism.

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