malines and beryl and are found in pegmatites. The latter are
p
artially banded,
consisting of a layer of graphic granite next to the hanging wall, a
streak of very coarse pegmatite, the "mineral sheet" carrying the gems,
a band of nearly pure potash feldspar, a garnet streak, and another
band of graphic granite next to the foot wall. The tourmaline occurs in
pockets, and the beryls are generally embedded in the "mineral sheet."
The
mine of the Maine Tourmaline Company, at Auburn, is on the gentle
slopes on the southeast side of Mount Apatite. The pegmatite outcrop
forms a ledge from 5 to 10 feet high and strikes northwest with a low
northeast dip. The country rock is mica schist which, with the
pegmatites, is cut by two small trap dikes. The structure of the
pegmatite is as follows: Upper graphic granite 4 to 6 feet thick,
"mineral sheet" 2 to 5 feet thick, feldspar zone below about 2 feet
thick, thin garnetiferous streak, lower graphic granite about 8 feet
thick. Mining is carried only to the garnet streak between the lower
graphic granite and the feldspar streak. The mine is opened by three
cuts, the largest of which is 30 by 50 feet across and 14 feet deep.
The rock is removed by blasting and the mineral sheet by small blasts
and pick where gem pockets are thought to be near. Near the pockets
transparent clevelandite and graphic tourmaline quartz are encountered.
Closer to the pockets lepidolite occurs and is often associated with
muscovite crystals, sometimes intergrown with it in the pockets. The
upper part of the pockets is generally lined with beautifully
crystallized quartz, mica, and clevelandite; the lower part contains
porous decomposed potash feldspar; occasionally pink and green
tourmaline crystals are grown into the upper crystallized surface of
the pocket, though generally the gems are in the clay at the bottom.
Many of the tourmaline crystals are broken or badly flawed, though a
few perfect ones are found. A number of the pockets are barren or "dead
pockets," and contain large quantities of lepidolite and apatite. The
quartz crystals in the gem pockets are coated with a thin crust of
minute crystals; those in the "dead pockets" do not have this coating.
This mine yields principally green and pink tourmalines, the latter in
smaller quantity. In 1904 a series of pockets were opened which
contained fine dark-blue tourmaline of nearly oriental sapphire shade.
The
cost of mining a ton of rock at the Maine Tourmaline Company's mine
during 1904 and 1905, exclusive of superintendence and office expenses,
was as follows: Labor, 28.3 cents; fuel, 2.3 cents; explosives, 5.9
cents; repairs, renewals, oil, etc., 0.4 cent; total, 36.9 cents.
The
Pulsifer mine is near the Maine Tourmaline Company's mine at Mount
Apatite. The deposit was opened in 1901 or 1902 by a small open cut.
One of the products of this mine consisted of nearly 3,000 transparent
purple apatite crystals all found in one pocket. The largest crystals
were about 2 inches long. The tourmaline crystals occur very much as
described above, and are of fine pink and green color. The small cut
has yielded many beautiful crystals.
The
Towne lease was taken up by the Maine Feldspar Company and operated by
a steam drill and derrick. The company worked for feldspar and left the
gems to Mr. Towne as a royalty. About $1,500 worth of green tourmaline
was obtained during 1907.
