Webster 1913 Edition



[Gr. [GREEK] to give besides; [GREEK] over + [GREEK] to give: cf. F.
. So named from the
of the base of the primary, in some of the secondary forms.]
A mineral, commonly of a yellowish green (pistachio) color, occurring granular, massive, columnar, and in monoclinic crystals. It is a silicate of alumina, lime, and oxide of iron, or manganese.
☞ The
Epidote group
includes ordinary epidote, zoisite or
lime epidote
, piedmontite or
manganese epidote
, allanite or
cerium epidote

Webster 1828 Edition



[From Gr.; so named from the apparent enlargement of the base of the prism in one direction. It is called by Werner, pistazit, and by Hausmann, thallit.]
A mineral occurring in lamellar, granular or compact masses, in loose grains, or in prismatic crystals of six or eight sides, and sometimes ten or twelve. Its color is commonly some shade of green, yellowish, bluish or blackish green. It has two varieties, zoisite and aranaceous or granular epidote.
Epidote is granular or manganesian.

Definition 2022



See also: épidote




epidote (plural epidotes)

  1. (mineralogy) Any of a class of mixed calcium iron aluminium sorosilicates found in metamorphic rocks.
    • 1915, George Curtis Martin, Bertrand Leroy Johnson, Ulysses Sherman Grant, Bulletin 587: Geology and Mineral Resources of Kenai Peninsula, Alaska, United States Geological Survey, page 23,
      A little higher is an outcrop of epidote schist with quartz, carbonate, and magnetite.
    • 1990, Andrew P. Barth, Chapter 3: Mid-crustal emplacement of Mesozoic plutons, San Gabriel Mountains, California, and implications for the geologic history of the San Gabriel terrane, J. Lawford Anderson (editor), The Nature and Origin of Cordilleran Magmatism, Memoir 174: The Nature and Origin of Cordilleran Magmatism, The Geological Society of America, page 36,
      Available compositional data for magmatic epidotes (Naney, 1983; Zen and Hammarstrom, 1984; Barth, unpublished data) suggest no significant solid solution beyond the epidote-clinozoisite binary.
    • 2004, Bruce Cairncross, Field Guide to Rocks and Minerals of Southern Africa, page 96,
      Epidote is found in greenstone belts and many metamorphic rocks such as gneiss and schist, and is hence fairly widespread.