96 THE GEANITES OF MAINE. 
The product has been thus far used for culverts and similar struc- 
tures on the Maine Central and Washington County railroads. 
The Black Island quarries are in the northeastern part of Black 
Island, which lies south of Mount Desert, in the town of Long Island. 
Operators, Black Island Granite Company, J. E. Dutton, president, 
42 East Twenty-third street, New York. 
The quarries, opened in 1892, consist of two openings. The upper 
one, about one-fourth mile south of dock at northeastern corner of 
island, measures 500 by 300 feet and from 10 to 40 feet in depth, and 
the lower one, known as the " Redcliff," a little south of the dock 
is about 100 feet square. There is no drainage to contend with. 
The granites taken from these two openings differ. Specimen 31, a 
from the upper quarry, is a biotite granite of pale pinkish-gray colo 
and medium (inclining to coarse) even-grained texture, consisting, 
in descending order of abundance, of potash feldspar (microcliue 
and orthoclase), smoky quartz, soda-lime feldspar (oligoclase), and 
very little black mica (biotite), together with accessory titanite and 
magnetite. Both feldspars are light pink. The potash feldspar is 
sometimes rimmed with oligoclase. The latter is often partially 
altered to kaolin and a white mica. The rock presents but faint con- 
trasts of color and, owing to the small quant ity of its mica, must needs 
take a very fine polish. 
The granite (specimen 39, a) of the Bedcliff quarry is a biotite 
granite of grayish-pink color and medium (inclining to coarse) even- 
grained texture, consisting, in descending order of abundance, of pot- 
ash feldspar (microcliue and orthoclase), smoky quartz, soda-lini( 
feldspar (oligoclase), and very little black mica (biotite), togethei 
with accessory titanite, magnetite, and zircon. Both feldspars an 
pinkish. The oligoclase is largely altered to kaolin and a white mica 
Its small content of mica must make this granite susceptible of higl 
polish. 
Rock structure : At the upper quarry the sheets, from 8 inches t j 
5 feet thick, are horizontal, with minor undulations. Vertical joints 
strike N. 70° W., recurring at intervals of 100, 200, and 250 feev 
The rift is parallel to these, but feeble. Sap, 3 inches thick, is cor- 
fined entirely to the upper sheets. At the Redcliff quarry the sheet 1 
up to 6 feet in thickness, bend over from the horizontal to 25° N. an 1 
NE. Vertical joints, striking N. 77° E., recur at intervals of 50 fee 
Another set, striking N. 35° E., abounds at the sides of the quarr 
but is scarce in center. Joints of this strike are numerous along tl I 
north shore of the island. The rift is vertical, with a N. 77° T 
course. 
The plant consists of 3 derricks, 2 engines, and 3 steam drills 
the upper quarry; 1 derrick at the wharf; 2 derricks and engine ar : ; 
polisher run by the same at the lower quarry. 
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