Epidote is a common mineral in greenschist facies metabasic rocks and some granitic rocks, where it is typically the dominant Ca-bearing mineral, and coexists with albite-rich plagioclase.  Epidote has high positive relief relative to quartz and feldspars (A, B, C).  It also has distinct pleochroism in shades of pale yellow/yellow green, seen in A and B (which are rotated 90 degrees relative to one another).  The epidote grains in C are not strongly coloured.  Characteristic bright interference colours (maximum of second and third order) are evident in D.  A and B are from the Tibbit Hill greenschist facies metabasalt, Sutton, Quebec and C and D are from an uknown location.  Images A and B are 2.2 mm across, C and D are 5.5 mm across.  A, B, C ppl, D x-nicols.