quartz
5 to 12 inches thick. In other parts of the pegmatite were coarse
crystals of quartz and feldspar. No topaz was observr at the Amarine
prospects, but Mr. Amarine reports that some was found.
TOURMALINE.
CALIFORNIA.
Mr.
J. W. Ware, of San Diego, Cal., reports the discovery of a deposit of
beautiful "Nile green tourmaline at his "Mountain Lily" mine on Aguanga
Mountain, in San Diego County. Many of these tourmaline crystals are of
fine gem quality and have yielded beautiful cut stones. The tourmaline
has not been found in large deposits and the associated minerals,
quartz, lepidolite, orthoclase, and albite are similar to those in
other tourmaline mines of San Diego County.
MAINE.
There
was but little activity in the mining of tourmaline in Maine during
1913. A few discoveries of crystals were made in the course of feldspar
mining on Mount Apatite near Auburn, but none of these were of great
value. Brief visits were made to some of the Maine tourmaline deposits
in June, 1913, and the information gained has been used along with
abstracts from a report by E. S. Bastin.1
Developments
have been limited at the Mount Mica tourmaline mine, 1J miles east of
Paris, Maine, during the last two years, and the results of these
operations have not been very promising. A good description of this
mine has been given by Bastin, and the earlier history by A. C. Hamlin.2
A
large area on the summit of the hill has been worked over by an open
quarry, which has progressed from the northwest to the southeast, with
an irregular working face over 200 feet long. The early work was close
to the surface but the dip of the formation has carried the work to the
southeast deeper, until it is now 20 to 30 feet deep along the face of
the cut. No work was in progress at the time of examination in June,
1913, and the deeper parts of the cut were filled with water. Waste
rock was rolled from the quarry floor to the hillside at the southwest
end of the cut. Near the middle it was hoisted by derrick and piled
back to the northwest on worked out ground or run on car and track
conveniently located for such purpose.
The
country rock is mica gneiss composed of layers or bands of schist, with
varying texture and composition, injected by numerous layers and sheets
of pegmatite. The schists are composed of numerous minerals, among
which are quartz, muscovite, biotite, feldspar, garnet, and a finely
columnar or fibrous mineral, probably fibrolite. The strikes measured
on the schist were quite variable from nearly east and west to west of
north, with dips of 10° to 25° to the soutn and east. The vein rock is
pegmatite, the gems occurring in the upper part of a large mass of this
rock, the thickness of which is not exposed. The gem-bearing layer of
pegmatite is about 7 feet thick in places. It contains numerous
cavities or pockets ranging from less than a pint in capacity to
several feet across. This gem-bearing layer
i
Geology of the pegmatites and associated rocks of Maine: TJ. S. Geol.
Surrey Bui. 445,1911. > The history of Mount Mica, Bangor, Maine,
1895.
