92 PEGMATITES AND ASSOCIATED ROCKS OF MAINE.
length,
is a beautiful sapphire blue, changing at the top into a delicate
green. It is about 4 inches long and one-half inch in diameter. It is
illustrated in color in "The history of Mount Mica," Plate XXVI.
A
remarkable curved crystal of gray to green tourmaline, transparent to
translucent in places, was found in 1891, and is now in the Carter
collection in the public library at Paris. It is about 5 inches long
and three-fourths to 1 inch in diameter, and is curved through an angle
of about 20°.
The
largest flawless gem ever cut from tourmaline from Mount Mica weighs
69-1/4 carats and is now in the Tiffany collection. It was part of a
crystal found in November, 1893, and was sold by Merrill & Stone
for $1,000. The crystal from which it came is described and figured in
"The history of Mount Mica," page 71 and Plate XLIII. It yielded a
number of other fine gems, one of which, a pink one, weighed 18 carats.
What
is probably the largest flawless piece of transparent tourmaline known
is in the possession of L. B. Merrill, its finder, the present operator
of the Mount Mica mine. In its uncut condition it weighs 411 carats. It
formed the tip of a crystal 8 inches long and 1 inch in diameter, much
of which was greatly disintegrated.
Beryl
occurs principally in the solid pegmatite, though occasionally found in
the pockets. The varieties found in the solid pegmatite are mainly pale
blue-green and opaque or translucent. Certain small portions of the
crystals may be transparent, and from these some small aquamarines of
good quality have been cut. One beryl 6 inches across, observed by the
writer, inclosed both muscovite and black tourmaline. The beryl found
in the pockets is mostly colorless to pale pink caesium beryl; it cuts
into gems which in artificial light have almost the beauty of diamonds.
It is apt to occur in short, button-shaped prisms, many with both
terminations complete. Two fine specimens of caesium beryl are in the
Hamlin collection at the Paris public library. One is about 6 inches in
diameter and 1 inch high and has three sides of the hexagonal prism
perfect. The other is about 6 inches high, shows a good basal plane,
four prism faces quite perfect for most of their length, and two
pyramid faces. These crystals are only in small part transparent and
are much flawed and iron stained along fractures.
Production and method of mining.—It
is impossible accurately to estimate the amount and value of material
for gems and museum specimens which Mount Mica has yielded, but Hamlin
in his history of Mount Mica estimated" that up to 1895 the locality
had yielded more than 100 tourmaline crystals which would be considered
unusually fine specimens of the mineral, besides many thousand smaller
crystals. The total value of the gems and cabinet specimens which have
been taken from the locality up to the present day probably exceeds
$50,000.
