library at Paris and is a clear, perfect piece of roughly hexagonal outline, measuring about 8 by 2-1/2 inches.
Good specimens of plumose mica, produced by close-spaced ruling, are
also to be found in the collections at Paris. Where not too intimately
mixed with other minerals, the mica is saved in the quarrying process
and has brought $25 per ton as taken from the quarry. At another time \2\ cents
per pound was offered for the thumb-trimmed product. The largest
perfect plates of cut mica obtained from this material would probably
not exceed 3 by 4 inches in size. Much is defective owing to wedge
structure and ruling and is valuable only as scrap mica.
Biotite
is not abundant, but it occurs in a few places in its usual form of
long, narrow, and very thin crystals, the largest seen being 10 inches
long and one-half inch wide.
Lepidolite
or lithium mica is of common occurrence in the pocket-bearing portions
of the pegmatite. The largest mass found, though impure, is reported as
weighing 10 tons, and it is not difficult to obtain fairly pure masses
8 or 10 inches across. The mineral occurs mostly in the granular forms,
though some curved and globular crystals have been found. The color
varies from lavender to peach-blossom pink. The granular varieties
commonly show some admixture of quartz, muscovite, and clevelandite
and not uncommonly contain interbedded crystals of opaque pink and more
rarely green tourmaline; some specimens which have been sawed into
small blocks and polished make handsome paperweights. Lepidolite from
this locality has been described by Clarke, who also gives analyses."
Black
tourmaline or schorl, which is the most abundant iron-bearing mineral
present at the quarry, occurs in prismatic crystals, mostly compound,
many of which are a foot in length and 4 to 5 inches in diameter. A few
having a length of 2-1/2 feet were seen by the writer, and one 4 feet
in length is described by Hamlin. A few large compound prisms of black
tourmaline separate at their ends into a brushlike aggregate of small
prisms, the interspaces being filled with quartz and an aggregate of
minute muscovite scales. The black tourmalines occur in the solid
pegmatite, penetrating it in all directions; except for a few small
crystals, they have never been found in pockets. Some colored
tourmalines occur in the solid pegmatite near the pockets, associated
usually with clevelandite, muscovite, lepidolite, and quartz; a few of
these are curved through considerable angles. Most of these colored
crystals are opaque, though a few small, delicate, transparent ones are
interleaved with muscovite. Fine specimens of these latter are found in
the Carter collection in the public library at Paris; other specimens
are much larger, some containing interleaved tourmalines 3 or 4 inches
in length and one-fourth inch or so in thickness. In a few instances
tourmalines
a Clarke, F. W., Lepidolite of Maine: Bull. U. S. Geol. Survey No. 42,1887, p. 13.
