Webster's Revised Unabridged Dictionary · 1913

Epidote

Epidote , noun

[Greek {not transcribed} to give besides; {not transcribed} over + {not transcribed} to give: compare French épidote. So named from the enlargement of the base of the primary, in some of the secondary forms.]

(Mineralogy) 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.