Much
of the turquoise appears to have been deposited from solutions in
crevices and cavities both in quartz and in other matrix, and some
seems to be a replacement of another mineral, probably the feldspar or
the kaolin formed from the feldspar. The rock is considerably stained
with copper, and in places the kaolin takes on the color of turquoise.
The
monthly output from the Aztec Company mines is stated to be between 1
and 2 cubic feet. This is shipped to New York, and the bulk of it is
sold in the rough, though the company also elaborates some of its own
material and works it up into jewelry. The sizes obtained vary from
particles too small for use to pieces 2 or 3 inches through. The best
color is considered to be the pigeon blue. The dark blue, though very
fine, appears greenish under electric light. The greater part of the
product is partly off color, and it is very difficult to btain
turquoise of the correct shade.
The
home production of turquoise reported to the Survey came from New
Mexico and Arizona. The large decrease in value was due to the closing
down of many mines by some of the hitherto large producers. In New
Mexico the Porterfield Turquoise Mines Company operated its deposits in
the Burro Mountains, Grant County, about 12 miles southwest of Silver
City, opening new ground during the year.
PERSIA.
According to Maj. R. L. Kennion,athe
turquoise mines near Nishapur (concessions for which are sold annually
by the Shah's Government) are the most important mines of the
Khorassan. The mines are worked in an unscientific and reckless way,
each concessionaire trying to get a maximum production from his mine
for the year. If leases of greater duration could be obtained,
systematic working would doubtless be undertaken. The present profits
are large, but can not be estimated.
UTZAHLITE.
The
production of utahlite was again entirely from Utah and from the
localities already described by Doctor Kunz in these reports.6 According
to Mr. Don Maguire, of Ogden, the value of the output from Clay Canyon,
Utah County, and from the Mercur locality, Tooele County, was about the
same.
GEM MINERALS OF MAINE.
The
following notes on the occurrence of the gem minerals of Maine have
been abstracted from a manuscript report by Mr. Edson S. Bastin on the
feldspar, quartz, mica, and gem deposits of that State, to be published
as a bulletin by this Survey:
The
gem minerals described are tourmaline, topaz, quartz, and beryl. They
occur as accessory minerals in pegmatite. The latter is composed of
feldspar, quartz, and mica in coarse-grained aggregates, and occurs as
intrusive masses in closely folded slates and schists. These intrusive
masses follow, in general, the bedding planes and schis-
a Mining Jour. (London), Novembers, 1906.
6 Mineral Resources U. S. for 1904 and 1905, U. S. Geol. Survey, 1905 and 1906.
