- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
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.