ملف:Quartz monzonite 36mw1037.jpg

English: Bedrock sample from a UGSG drill core at Western Cape Cod, Massachusetts. Sample 36MW1037, a quartz monzonite, contains plagioclase (45%), K-feldspar (35%), quartz (15%), biotite (3%), and trace amounts of garnet, chlorite, oxides, epidote, and sphene. Seritized plagioclase is intergrown with K-feldspar and in some places shows unaltered zones that may suggest regrowth. Perthitic K-feldspar porphyries show tartan and some carlsbad twinning. Quartz occurs in domains up to 3 mm thick, and commonly exhibits subgrain development and undulose extinction. Biotite is chloritized near its edges. Garnet occurs as small (0.2 mm) rounded isotropic inclusions within altered plagioclase.