138 PEGMATITES AND ASSOCIATED ROCKS OF MAINE.
rial
at present come from South Dakota and Colorado. ' In Maine it forms
irregular masses in the pegmatite and usually grades into white quartz;
it has not been found in distinct crystals. It occurs in a number of
the smaller pegmatite bodies of Oxford County, notably at Tubbs Ledge
in Norway, Frenchs Mountain in Albany, and occasionally at Mount Mica
in Paris, but so far as known very little has been marketed. In a few
places the pale-rose varieties show a milky opalescence and are very
beautiful when well polished.
Rose
quartz from the Red Rose mine in South Dakota, is reported to have sold
in 1908 at from 3 to 25 cents per pound, according to depth of color
and number of flaws or seams. Selected material brought from $8 to $12
per pound.
AMETHYST.
Amethystine
quartz, or amethyst as it is commonly called, is a transparent purple
or violet variety of quartz and is one of the semiprecious stones. It
must not be confused with the oriental amethyst, which is a rare purple
variety of corundum and is much more precious. Deer Hill in the extreme
northwestern part of the town of Stow, Oxford County, has furnished
large numbers of amethyst crystals, but nearly all of them are of a
pale tint and of little value as gems. They occur in pockets in the
coarse pegmatite and also in the soil on the southeast slope of the
hill, where the pegmatite is associated in a most irregular manner with
fine-grained granite. Recently George Howe, of Norway, Maine, has found
some remarkably fine specimens of amethyst on Pleasant Mountain, in
the town of Denmark, Oxford County. By transmitted daylight these
stones are a deep royal purple, but by lamplight they are a rich wine
red.
As
in the case of most other Maine gems, the retail prices obtained within
the State for Maine amethysts are considerably higher than those
prevailing in the New York market. They range up to $10 a carat for
well-cut stones of the paler varieties, and from $10 to $18 a carat for
those showing the deep colors.
MICA.
Types.—Mica
is a group name comprising a number of mineral species, the most
important of which, economically, are biotite (brown mica), muscovite
(white mica), phlogopite- (amber mica), and lepi-dolite (pink or lilac
mica). Though biotite is occasionally ground for commercial purposes,
it is so intimately intergrown with other constituents in the Maine
pegmatites as to be unavailable even for such treatment. Lepidolite
from Mount Mica, usually intergrown with some albite feldspar, has been
cut into slabs and polished for paper weights, and has also been used
to some extent as a source of lithium
