Sample 82MW0008, an orthogneiss, is composed of the
minerals K-feldspar (35%), plagioclase (32%), quartz (25%), biotite
(3%), epidote (2%), chlorite (2%), and trace sphene and oxides. This
foliated rock is characterized by porphyroclasts of K-feldspar (up to 8
mm) wrapped by biotite, chlorite, and quartz aggregates. Plagioclase
occurs mainly as recrystallized matrix grains, though some severely
altered porphyroclasts are present. Shearing is evidenced by quartz
subgrains and undulose extinction, as well as by mica texture. Chlorite
partially replaces biotite. |