Shrewsbury Quadrangle, Barosh DESCRIPTION OF MAP UNITS IGNEOUS ROCKS

Gabbro-Quartz Diorite, medium- to dark-gray or dark greenish gray, weathering same or darker with a brownish cast, fine- to medium-grained, equagranular to seriate, massive rock consisting of Hornblende biotite gabbro, hornblende biotite diorite and some hornblende biotite quartz diorite. The biotite flakes of different orientations form clots,,5- 1 cm across, in places. Grew (1970) reports the different rock types form layers 1 to 2 meters in thickness. The gabbro-quartz diorite appears to be the youngest intrusive body in the quadrangle because of the lack of apparent regional metamorphic foliation, mqm Muscovite Quartz Monzonite, light-gray weathering about the same, equagranular, massive to moderately foliated, medium-grained rock approximately muscovite or muscovite biotite quartz monzonite, Its contact with the Nashoba formation is very broadly gradationa