274 Buell—Geology of the Waterloo Quartzite Area. 
grains are larger, less elongated, and have a smaller amount of 
finely comminuted quartz as interstitial material, indicating 
that it has been subjected to less disturbance than the last. 
x25. 
Fig. 5. Section of Mud Lake quartzite. The large quartz 
grains are elongated and have wavy extinction, interlocking 
with one another without interstitial material, the axial direc¬ 
tion of the interlocking areas being essentially parallel. Seri- 
cite occurs in small scattered areas. x25. 
Fig. 6. Section of Mud Lake quartzite. Sericite and liquid 
inclusions in a single quartz individual. The sericite fre¬ 
quently shows hexagonal outlines and is arranged along the 
fracture lines like the liquid inclusions. The latter divide the 
surface into irregular areas. x25. 
PLATE IX. 
Fig. 1. Section of Portland quartzite. The quartz is in 
clusters of angular interlocking grains. The interstitial ma¬ 
terial is chiefly sericite. Crossed nicols. x40. 
Fig. 2. Sections of red quartzite. The quartz grains are 
more evenly distributed than in the last, are of smaller dimen¬ 
sions, and are accompanied by a larger proportion of sericitic 
interstitial material. Crossed nicols. x40. 
