GRANTTE GENISS [N CONNECTICUT 647 
granite-gneiss, only somewhat more basic than the general rock. 
The absence of any evidence of crushing in the sections shows 
that their present lenticular and banded form was attained while 
the rock was still unsolidified. 
3. Lhe ‘‘augen’’-gneiss— Frequently the granite-gneiss be- 
comes a decided ‘‘augen’”’-gneiss. Its distribution is indicated 
as nearly as possible on the map. It attains its best develop- 
ment along the northeastern border of the granite-gneiss and 
in the narrow tongue that runs north into the schist. The 
‘“‘augen’’-gneiss often passes gradually into the ordinary granite- 
gneiss, with which it is identical in mineralogical composition 
and in structure, with the single exception of the occurrence of 
sub-porphyritic feldspar crystals and aggregates. A surface 
broken at right angles to the foliation shows a light gray gneiss, 
dotted with more or less distinct ‘‘augen” of white or pink feld- 
spar, averaging three fourths of an inch in length, and with a 
parallel arrangement, around and between which run the lines of 
biotite flakes. The feldspar of the ‘‘augen” often reflects light 
as a single crystal, either simple or a Carlsbad twin, and rarely 
this crystal is roughly rectangular, yet it never possesses crystal 
boundaries. Quite commonly the cleavage surface of these 
broken crystals shows dull rounded areas of feldspar which are 
differently oriented grains included within the larger crystal. 
Where a single crystal occurs it forms the irregularly margined 
core of the “‘auge”’ and is surrounded by a dull white rim com- 
posed of an aggregate of fine feldspar grains. As the core is 
pink and the rim white, there is a further contrast between 
the two. Much more often than not, however, the reddish core 
does not reflect as a unit, but consists of an aggregate of grains, 
still flesh-colored and coarser than the rim. In other cases the 
‘‘augen”’ consist of aggregates of white feldspars without any 
reddish cores. 
It looks very much in the hand specimen as if those reddish 
cores of the ‘“‘augen,” which are composed of an aggregate of 
grains, were derived from the fracturing of single grains, which 
in some cases seem to remain partly intact at the center. But 
