PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 169 
the so-called Scotch granite so extensively used for monuments and 
ornamental work. 
The red granite of Jonesborough in general appearance agrees closely 
with the Red Beach rock, and under the microscope is found to differ 
only in its increased amount of plagioclase. The evenness of the grain 
and the occurrence of the mica only in small amount and in minute 
flakes are matters of practical importance, since they allow the pro- 
duction of a more perfect surface and lasting polish than would other- 
wise be possible. These granites are both used extensively for monu- 
mental purposes, and have but few blemishes, chief among which are 
the black patches to be noticed later. 
At West Sullivan a compact gray granite of medium texture is ex- 
tensively quarried, which is used largely for building and paving pur- 
poses. It is an excellent stone, and corresponds in general appearance 
very closely with that produced at the quarries of the Blaisdell Bros., 
in the town of Franklin. 
The Somesville, Mount Desert, granite is of coarse texture and of a 
slight pinkish tinge, due to the orthoclase which is often present in 
crystals of sufficient size to give the rock a slight porphyritic struct- 
ure. The feldspars as seen under the microscope are quite turbid and 
opaque, and the mica is often greenish, occurring only in small, ragged 
shreds. Very many magnetite granules were noticed in this rock, as well 
as a few zircons and irregular grains of sphene, which are often partially 
inclosed in the mica folia. A red granite is also found at Somesville 
which is hornblendic, and will be noticed further under the head of horn- 
blende granites. 
From the vicinity of East Blue Hill have been received some of the 
most beautiful of the gray granites quarried in the State. Asa general 
thing these granites are of rather coarse texture and uniform gray color, 
though many of them are rendered porphyritie through the prevalence 
of large snow-white twin crystals of orthoclase scattered throughout 
the finer gray groundmass composing the rock. For monumental pur- 
poses this porphyritic variety is one of the most beautiful of our gray 
granites. A portion of the granite from this region is of a pinkish color, 
similar to that of Mount Desert. As seen under the microscope, the 
biotite in the East Blue Hill rock is often altered into a faint bluish- 
green product scarcely at all acted upon by polarized light, and bearing 
very numerous inclosures of black opaque grains and needle-Jike bodies, 
which are doubtless magnetite. All stages of alteration are found, from 
the strongly dichroic smoky-brown biotite, with scarcely a trace of mag. 
netite, tothe greenish, almost isotropic substance penetrated in every 
direction by the magnetite needles. A little muscovite is often present, 
as well as a few zircons. 
The Deer Isle granite is quite coarse and of a gray color. Large 
pinkish orthoclase crystals make up the bulk of the rock, and but little 
mica is present. The rock bears a strong resemblance to that of the 
