Epidote is one of those greenish minerals that can be hard to tell apart in the metamorphic rocks of my area--it and chlorite and serpentine. I got this definitive specimen in a rock shop, where epidote coexists with pink feldspar and dark quartz. With some practice I should be more confident in the field. (Of course, it's supposed to rain for the next two weeks here. I will have to huddle indoors and study this specimen instead.) Learn more about epidote in the Mineral Picture Gallery.
Epidote in "unakite" Geology Guide photo