ANORTHOSITE-GABBRO IN NORTHERN NEW YORK 31 
clusters or as scattering grains. There is some very local granu- 
lation, especially of the feldspars. 
No. 39 of the table represents a thin section of a light greenish- 
gray, medium-grained, moderately ophitic gabbro from locality 8. 
The andesine is much altered, mostly to scapolite. The pyroxene 
(probably diallage) is pale green to colorless. Tiny black inclusions 
init are common. Most of the hornblende forms distinct granular 
rims around the pyroxenes, but a good deal of it is elsewhere 
interlocked with the pyroxenes. There is some granulation of the 
feldspars in local zones only. 
No. 51 of the table is from a specimen of the very common 
dark-gray, non-foliated, medium-grained to fine-grained gabbro 
with ophitic texture from locality 7. 
At locality 6 the main body of the rock is a medium-grained to 
moderately coarse-grained gabbro with a crude ophitic texture. 
The feldspar laths range up to three-fourths of an inch in length. 
No. 47 of the table shows the minerals contained in a thin section. 
Common green hornblende occurs mostly as narrow rims around 
both pyroxene and magnetite. Small inclusions of hornblende 
occur in the plagioclase. Granulation is lacking. Lying within 
the rock just described there is a zone of distinctly porphyritic, 
non-foliated gabbro about a rod wide, without sharp contacts. 
A hand specimen shows scattering, irregularly arranged, broad, dark 
laths of plagioclase up to one-half of an inch in length imbedded 
in a fine-grained dark-gray groundmass. No. 46 of the table 
shows the minerals observed in a thin section. Much of the 
feldspar has been altered, chiefly to scapolite. There is apparently 
no granulation, but considerable masses of fine granular horn- 
blende, pyroxene, biotite, and plagioclase fill large spaces between, 
and cracks in, the feldspar phenocrysts. A good many grains of 
biotite, hornblende, and pyroxene are also irregularly scattered 
through the feldspars. 
In a ledge at locality 1 most of the rock is a coarse-grained 
hornblende-rich facies of the gabbro. This rock is light gray, due 
to whiteness of the feldspars, which range in length from the merest 
fraction of an inch to several inches. Most of the feldspars are 
distinctly euhedral. A coarse ophitic texture is usually well 
