A granite, sample 82MW0002 contains K-feldspar
(30%), plagioclase (30%), quartz (30%), chlorite (5%), sericite (2%),
oxides (2%), and trace sphene and epidote. Perthitic, tartan and
Carlsbad twinned K-feldspar porphyries show undulose extinction and
irregular grain boundaries. Pinkish-tan plagioclase is heavily altered
to epidote and sericite, and shows little twinning. Quartz grains
exhibit serrated boundaries, subgrain development and undulose
extinction. Large domains of chlorite/epidote/sphene are common as a
"hash" of mafics/alteration products. Chlorite occurs in large (4-mm)
aggregates, yet does not define a foliation. Fractures in this rock are
filled with calcite and oxides. |