epidote

plural epidotes

1. countableuncountablechemistryAny of a class of mixed calcium iron aluminium sorosilicates found in metamorphic rocks.

   A little higher is an outcrop of epidote schist with quartz, carbonate, and magnetite.

   1915, George Curtis Martin, Bertrand Leroy Johnson, Ulysses Sherman Grant, “Bulletin 587: Geology and Mineral Resources of Kenai Peninsula, Alaska”, in United States Geological Survey, page 23

   2 more examples

   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of America, page 36, Available compositional data for magmatic epidotes (Naney, 1983; Zen and Hammarstrom, 1984; Barth, unpublished data) suggest no significant solid solution beyond the epidote-clinozoisite binary.

   Epidote is found in greenstone belts and many metamorphic rocks such as gneiss and schist, and is hence fairly widespread.

   2004, Bruce Cairncross, Field Guide to Rocks and Minerals of Southern Africa, page 96