Barbour County index. [volume] (Medicine Lodge, Kan.) 1880-current, 1905-06-28
MOLYBDENITE NINE.
ORE USED IN MANUFACTURE OF
STEEL FOUND IN MAINE.
Deposits Are of Rare Occurrence and
the Value Of Those Located
Is Partly Conjec-
tural.


One of the principal deposits OF
| molybdenum ore in this country is at
Cooper, Me. 1t was visited in Sep
| TENDER, 1904, by DR.. George Otis
Smith, of the United States geological
survey, who tells in bulletin 26O, the
surveys annual publication on its ex-
| PLOTS in economic geology, how the
American Molybdenum company pre-
| vented him from having more to say
about the molybdenum of this locality.
He was not permitted to visit the mine,
| but the observations he made at the
surface furnished him sufficient data
| for consideration of the character and
| origin of the deposit.
The town of Cooper is in Washing
| ton county, in the extreme southeastern
| part of Maine, and is the fourth town
ship west of Calais. The nearest rail-
road station is Marion, in the second
! township south Prospecting for mo-
| lybdenite has been carried on at sew
eral points in this locality, but the only
| important development thus far is that
| on the property of the American Mo-
| lybdenum company.
The molybdenite occurs both in peg
Matte dykes and in the granite cut by
| these dykes A number of distinct peg
Matte dykes were seen on this property,
| varying in width from a few inches to
| several feet In these the mOlybdenite
occurs in lead-gray hexagonal crystals
Of short prismatic habit. or as less reg
ular foliated masses, often with radlate
| structure The molybdenite is found
also in small flakes or larger nests Of
| flakes disseminated throughout the
granite mass.
Molybdenite occurs at several other
| localities in Maine, as we'll as in the
other New England states 1t is usu-
ally found in small flakes disseminated
| through the granite or gneiss, so that
| the Cooper occurrence is of special
| interest by reason of the light it
throws on the origin of this mineral.
The pegmatite dykes are probably
approximately cOntempOraneOus with
| the granite intrusion, representing
the latest crystallization of the gran
| itic magma and therefore intrudlng
the consolidated granite. In this
pegmatite magma molybdenun disul-
phide appears to have been a promi-
nent constituent and to have crystal
lized early in the consolidation of the
| dykes. The molybdeTite in the gran
| lite may be either the result of impreg-
nation at the time of the pegmatitic
intrusion or it may be an original con-
stituent. The former view is support
| ed by the apparently larger amount in
| the granite near the dykes
The ores of molybdenum have been
in greater demand since molybdenum
| has been used in the manufacture Of
steel to increase it's hardness and
toughness. The comparative rarity and
| high cost of the ores, have, however,
limited its use.
The economic value of such deposit
as the Cooper molybdenite is partly con-
jectural. The conditions for quarrying
and mining both the pegmatite and the
wall rock appear favorable, and con-
siderable work of this kind has been
done. The rock lying on the dump
contained varying proportions of mo-
lybdenite, but it seemed that most of
the crude ore could be readily distin-
guished and separated from the barren
rock by hand picking. The crucial test
of the successful working of such a de-
post is doubtless connected with the
milling process. rather than with the
mining methods. A compact plant for
treating the molybdenite ore has been
erected by this company. but the de-
tails as to cost of crushing the rock and
Of concentrating and cleansing the sep
arated mineral could not be ascertained