epidote

n. [ Gr. &unr_; to give besides; &unr_; over + &unr_; to give: cf. F. épidote. So named from the enlargement of the base of the primary, in some of the secondary forms. ] (Min.) 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. [ 1913 Webster ]

☞ The Epidote group includes ordinary epidote, zoisite or lime epidote, piedmontite or manganese epidote, allanite or cerium epidote. [ 1913 Webster ]