An epidiorite sill is intruded in quartzites at Tallabrista, County Donegal, northwest Ireland. At its northern end the sill is homogeneous, but southward it contains quartzite and amphibole xenoliths with large plates of plagioclase and hornblende in the matrix. The sill is considered to be a pre-metamorphic magmatic intrusion, and the amphibole xenoliths were originally impure limestone.

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