ADIRONDACK BASIC INTRUSIVES 167 
hornblende norites; No. 5 is a hornblende gabbro; No. 8 is a 
gabbro-diorite; Nos. 10, 13, and 14 are hornblende syenites; No. 11 
is a monzonite; and No. 12 is a diorite. The large number of 
minerals—16 in all—is also notable. Also it is important to note 
that, in the above table, Nos. 3 and 4, 7 and 8, 9 and 10, and 11 
and 12, respectively, come from single stocks. 
The predominating mineral is feldspar, which ranges from 
labradorite alone in some rocks through all stages, to those rocks 
which are rich in the more acid plagioclases or orthoclase. 
Hornblende, generally in considerable amount, occurs in all 
but one (No. 1) of the rocks. Sometimes it makes up a fourth 
or more of the whole rock. Much of the hornblende in the more 
basic rocks, at least, is of secondary origin and forms corrosion 
rims (below described) around other minerals. Its color varies 
from green to brown. In one slide many examples of the transi- 
tion from pyroxene to hornblende are perfectly shown. 
Hypersthene, with a single exception (No. 5), is an important 
constituent of all the more basic types. It is almost always highly 
granulated and with pleochroism from greenish-gray to pale 
reddish-brown. 
Augite and diallage of greenish-gray color, and with good 
cleavage, are only occasionally present and rarely as important 
constituents. 
Ilmenite is invariably present in amounts up to 5 per cent, and 
often shows transition to leucoxene. 
Pyrite in small amount seldom fails. 
Biotite and garnet of the usual sort, though mostly in tiny 
flakes or grains, are present in moderate quantity in all but certain 
of the more acidic facies. The unusually high percentage of garnet 
in No. 4 is a fine grained border phase of a stock. 
Quartz, in small irregular shaped grains, is wholly confined 
to the acidic types. 
Zoisite, in small stout prisms, sometimes makes up about 
1 per cent of the rock. 
Zircon and apatite, in very small quantities, are wholly con- 
fined to the acidic facies. The absence of the apatite from the 
typical gabbros is especially noteworthy. 
