The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1896-02-15
BY PROFESSOR WEED
His Writ:-Up of the Neihart Mining
District.
IN CHAMBERS AND POCKETS
The Ore as a Rule is Low Grade,
but There Have Been Some
Rich Specimens Found
Types of Deposits.
IN CHAMBERS AND POCKETS

Great Falls. Feb. 14.-Prof. w. II.
Weed who. as chief of the United
states geological survey, spent some
months in the Belt mountains last sum-
mer. contributes a paper in the current
number of Mining. a publication de-
voted to the mining interests of the
Northwest on the wide variety of ore
deposits found in the Neihart mining
district. MIR Weed says:
The Neihart district embraces the
mines in the vicinity of Barker. belong
To the types of silver and lead deposits
formed in limestones and occurring in
chambers and pockets and not in MS
sure veins, and also the similar MIN
ing regions of Dry Wolf and Running
Wolf creeks; the Yogo district, where
the ore-boaring solutions have followed
lines of contact between igneous rocks
and the sedimentary strata IN Whlch
they have been injected as well as the
mining district directly tributary 10
Neihart where the ores occur entirely
within the area of crystalline schists
and gniessps. The wide variety of ore
deposits included within these four
Sub-districtS makes 1t Impossible 10
give more than the salient features OF
each type of deposit within the brief
limits of the present article. As the
Neihart district itself is now the only
one which is productive, ii Will be con-
sidered in more detail than the others.
The mines include the silver-bearing
fissure veins in the vicinity of Neihart
itself, and the gold quartz veins of the
new camp known as johannesburg.
The silver ores are mainly galena, but
include also brittle silver, ruby silver
and more sparingly other silver sui
phides. Associated with these ores
there is consid arable heavy spar and
zincblende. These ores occur in narrow
grnaiGgRs and
associated rocks Of the Archean area.
THE Archean rocks include wide
variety of gneisses and schists which
show we'll differentiated horizons, the
beds dipping at steep angles and cut by
a great body of igneous rock. This ig
neOus rock occurs in stringers, bikes
and irregular intrusive masses extend
ing outward from the main body OF the
rock in every direction. and penetrat-
ing the gneisses in a most bewildering
way. There also occurs a quartz-por-
phyry, forming minor intrusions on the
summit of the mountains east of Nei-
hart and about the headwaters of
Snow creek. The gneissic series in
cludes alterations of white feldspar
gneiss, pink feldspar gncis, and black
mica schists. 1t is a significant fact
that the ore leads which cross these
rocks nearly at right angles to the
plains of apparent bedding are barren
or worthless wherever they occur in
the black mica-schist. These ore bodies
are intimately connected with the in
trusion of the coarsely granular.
spotted rock which is a syenite. The
ore bodies frequently expand in width
in the vicinity of the syenite, and Oft
entimes occur along the contact of this
rock and the feldspar gneisses. The
ore bodies do not pass upward into
the great series of quantities. which
rest upon the Archean rock. These
-Frrtt1 ,F1tI, h old -oIf
mentary rocks known in the Rocky
mountain region, are in no place cut
by the ore bearing leads which are
consequently older than the Algonklan
beds. In this respect the silver leads
of Neihart differ from the comparative
ly recent ore bodies of Barker. The
mines about Neihart embrace many
workable veins, but at present only a
few are being actively exploited. The
Broadwater mine was opened in 1898
and is now being actively worked de-
spite the low price Of silver.
The Florence mine is another prop
erty which is paying small dividends
under similarly discouraging condi-
tons. In both these mines the main
mass of the ore is silver bearing ga
lena, although the richer silver ores
also occur. In the mines of the Benton
group a narrow streak of rich ore oc-
ours in wider lead, the ore streak
varying from a few inches 10 a foot OF
more in width. is filed with a very rict
silver ore consisting of native silver
and the associated sulphdes. The ore
also carries a considerable amount Of
gold and We're II worked by itself would
be a very valuable property. At pres.
ent, however. the exploratory WORK
being conducted in the adjacent lead'
uses up returns from this extremely
productive lode.
Numerous other properties on tn,
slopes of Neihart mountains and tn,
country drained by Carpenter CrCel
and Snow creek have been opened. but
development ceased abruptly upon tn,
great decline in the price OF silver and
underground geology could only b.
conducted without great risk and Httl,
profit after the closing down Of tn,
mines. The study Of the surface Eeol
ogy shows. however. that under favor
able conditions the ore bodies in TIL
vicinity of Neihart would make IL ont
Of the most active mining towns in tn
state
Recent discoveries of rich gol,
quartz in the crystalline schists an,
CuCisses forming the nucleus OF tn
range a few miles north Of Neihar
have brought the region into recen
prominence. The gold occurs In fisSur
veins traversinC crystalline rocks. T
IS essentially a low grade ore. alth1u-l
very rich specimens have been obtain
81 from several IF tho leads II r.
mains 70 be seen whether the genera
rule which obtains for SO many Of m
gold quartz mines IN Montana. ina
t." free milling gold ore viii give on
at couple az hundred feet in depth
viii terminate the activity Of this re
gion-'
Hr Davis Carl.
Great Falls. Feb. I'm an open let