O. A. Vanhise—Enlargements of Feldspar. - 401 
feldspars penetrated by a saturating quartz. Next in order of 
abundance are complex fragments of some altered basic rocks. 
Finally a few grains of quartz and a little secondary calcite are 
oted 
ned twinning bands. e grains are all ro , their 
boundaries being marked by broad lines of ferrite. However 
2. 3. 
Fig. 2. In polarized light; x 100. Plagioclase from Eagle Harbor sandstone, _ 
showing crystallographic continuity of original grain and secondary enlarge- 
ment. 
Fig. 3. In polarized light; x 100. Fragment of a grain of a granitic porphyry 
from Eagle Harbor sandstone. ee 
This newly added material appears to be feldspar which has 
coordinated crystallographically with the grains about which 
it has deposited. It possesses, no optical properties which 
would exclude that mineral, but cleavage and decomposition 
being absent, no comparison with the feldspars can be made 
as to those characteristic features. The belief that the new | 
rita is feldspar is, however, supported by the following 
acts. ! 
When the enlarged feldspar is orthoclase, the deposited eube 
Stance polarizes uniformly with the nucleus about which itis 
