50 PEGMATITES AND ASSOCIATED ROCKS OF MAINE.
After
the expiration of the leases of the persons mentioned, no mining of
importance was done at Mount Apatite until 1902, when the Maine
Feldspar Company, now the largest operator at this locality, commenced
mining feldspar for use in pottery manufacture. Previously small
amounts of quartz had been mined and shipped for use in the manufacture
of sandpaper, and it is interesting to note that at this time the
feldspar was considered to be of no value and was thrown on the dump
piles. Although a few gems and cabinet specimens have been found in the
course of the feldspar mining and by collectors paying short visits to
Mount Apatite, regular mining for gems was not resumed until 1907, when
J. S. Towne commenced operations at a new locality (p. 55).
QUARRIES.
Maine Feldspar Company quarry and mill.—The
largest workings at Mount Apatite are those of the Maine Feldspar
Company, of Auburn, which commenced operations in 1902 and has operated
continuously to the present time (1909). The property was visited by
the writer in August, 1906, and again in October, 1907.
The
workings consist of a number of small pits 75 to 150 feet long, 50 feet
in average width, and 10 to 20 feet in depth. These are either close
together or partly connected and are located in a single mass of
pegmatite which constitutes the summit of the hill. Much of the hilltop
is bare, but in a few places as much as 6 feet of clayey till must be
stripped in working.
The
minerals present are those usually found in the granite pegmatites of
the Atlantic States which are worked for feldspar but include many
others that are characteristic only of the gem-bearing pegmatites.
Quartz
varies from white to dark gray in color and from opaque to beautifully
transparent. Its commonest occurrence is in graphic intergrowth with
feldspar, but it is found also in large pure masses and in clusters of
beautiful cr\Tstals projecting inward from the walls of
pockets or fallen into the mass of kaolin, cookeite, etc., at their
bottoms. Many of these groups of crystals are colorless and
transparent, but others, notably some found by Thomas F. Lamb in one
of the early workings near the Hatch farmhouse, though transparent, are
smoky. Some of these latter are 20 centimeters in length and many are
coated, especially at the tips of the pyramids, with thin white opaque
quartz, which is plainly of more recent development than the main mass
of the crystal. A few of the quartz crystals of the pockets are
penetrated by small colored tourmaline crystals. The quartz obtained in
the course of the present mining for feldspar is white and very pure
and is of excellent quality for any of the many purposes for which crystalline quartz is now used. It is saved in
