658 MINERAL RESOURCES, 1913----PART II.
smaller
gems weighing altogether over 300 carats. The other crystal was
smaller, one half having a transparent faint green and the other a
translucent green color.
Beryl
has been prospected at several places in the town of Buck-field, Me.
Besides the more common aquamarine varieties, golden beryl and
colorless to bluish caesium beryl are found. Some of the localities
which have yielded chiefly caesium beryl along with a few other
minerals of interest were visited.
The
Lewis mine, worked by Perien Dudley, is about 2 miles southwest of
Buckfield. It is in the eastern side, near the summit of a low but
steep-faced hill. The work consists of two connecting open extending up
and down the hillside for a distance of about 120 feet. The lower cut
has a direction of N. 20° W. and the upper one X. 80° W. up the hill.
They range from 5 to 15 feet in depth and 10 to 20 in width. The
country rock is quartz-biotite gneiss with layers of typical biotite
schist. The gem-bearing rock is pegmatite lying approximately
conformable with the gneiss which strikes about N. 30 E. and dips 30°
SE. Biotite schist overlies the pegmatite on south side of the cut, but
north of this the pegmatite appeal's to outcrop as a blanket ledge. It
had not been cut through in the open cuts and the thickness is
therefore not exposed. The pegmatite i-rather coarse, but uneven
grained. Orthoclase or microcline in rough crystals several inches
across and in graphic intergrowth with quartz. Translucent green and
bluish-green tourmaline with occasional pink crystals have been found
frozen in the pegmatite along with muscovite, biotite, and
clevelandite. Pockets ranging from small size to 2 feet in diameter are
reported to occur scattered irregularly through the pegmatite.
Colorless caesium beryl was found frozen in the pegmatite and also in
pockets. Arsenopyrite, or the related mineral lollingite, is present in
the pegmatite associated with various minerals.
Very
fine caesium beryls have been obtained from the mine of J. H. Fletcher,
a little over 2 miles southwest of Buckfield, Me., and about one-fourth
mile west of the Lewis mine. The Fletcher mine was also worked by
Perien Dudley and was opened by a cut extending north into the
hillside. The beryls occur in pegmatite inclosed in quartz-biotite
gneiss. The feldspar of the pegmatite is gravish othoclase or
microcline which occurs in crystals up to 2 feet thick. Dark
greenish-black tourmaline and clear light yellowish-green muscovite are
abundant. Many small fragments of brilliant transparent colorless and
pale greenish beryl were observed in the workings. Similar beryl in
larger pieces would yield gems of exceptional brilliance. The largest
beryl crystal found is reported to have been nearly 4 inches in
diameter with one end composed of clear gem material.
Beryl with other interesting minerals has been found in several prospects on the north slope of a hill 2-1/2 miles
southwest of Buckfield, Me., and about half a mile south of the
Fletcher caesium beryl mine. These different prospects have been opened
by Perien Dudley and W. S. Robinson. Much of the beryl found in these
prospects it nearly colorless or pale greenish, and contains caesium.
At two oi more of the prospects, pollucite, a hydrous silicate of
caesium and magnesium, is found along with beryl. In one opening masses
of pollucite 8 to 10 inches across were found. A few crystals of opaque
or translucent colored tourmaline have also been found in the pegma-
