The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1920-01-01

.ensIty vi The forces by WHOM the de-
posts We're formed and in smaller
part 10 the influence OF the wall rocks
y" the deposition OF the ores. The
deposits IN the Prichard rocks were
IoiHed unaer greater heat and press
u4e ,han those tne Wardner district
0a shown by the abundance Of spinal
critic in the Interstate Callahan Veins
oAd of sphalerlte and pyrrhotite in the
ems OF the Pine creek district and
~ the scarcity of siderite in the veins
vi the Nine Mile creek and Pine creek
"leaS. The occurrence of the lead ore
Shoots in the upper parts of the In
lerstate- Callahan veins also suggests
tAe conclusion that the galena was
generally deposited at higher horizons
IMAM sphalerite.
| That the character of the wall rocks
may Influence mineral deposition is
shown by several VEINS Of the, Pine
creek district that cut both the slate
and quartzite. Where quartzite forms
I
ant in the vein than where it is in
closed by slate.
Anthony Veins.
The antimony veins of the Pine
creek district, though few in number
are widely distributed in the area of
Prichard states. They are not con-
fined to one system of fractures, for all
have widely divergent strikes and
dips. These veins occupy fault tis-
sures in which lenses andS irregular
bodies of quartz commonly occur. They
differ markedly from the other veins
Of the district in mineral composition.
The principal metallic sulphide Is stib-
mite, which has been formed by re-
placement of either the slate wall
rocks or the quartz gangue. Pyrite is
a common constituent of these veins,
and here and there they contain
sphalerite.
Siderite Veins.
Manganiferous siderite veins occur
basin. These veins are simple assure
filings that are found in a west
ncrthwesterly zone between the Colusa
and Palisade prospects. The country
Revett and st. Regis formations. No
important ore bodies have yet been
developed in any of them, though
chalcopyrite occurs sparsely in some.
Depth of Oxidation.
The present ground water level is
nowhere far below the surface and in
most of the metalliferous veins of the
PINE creek district the oxidized zone
is shallow Commonly the sulphides
are found at or within a few feet of
the surface. The Hypotheek vein is
an exception and indeed this deposit is
unique in the Occur dAlene region in
that the oxidized ores in places ex-
tend HOO feet below the collar of the
shaft, or approximately 700 feet be-
lew the level of the Occur d'Alene
river. To account for this great depth
of oxidation three factors must be
considered-the permeability of the
Vein, probable change of the ground
water level, and possible downfault-
ing after oxidation. 1t is notable
that the greatest depth of oxidation
is in that part of the vein west Of a
northwesterly fault along which the
commercial bodies of lead ore occur.
Outside this lead ore shoot on the 700,
800 and 11OO-foot levels the ore is en-
the sulphides continued nearly to the
surface, but this could not be verified
because the 700foot level is the first
opening below the collar of the shaft.
The part Of tho vein that contains
the lead ore shoot has been extensive
ly fractured subsequent to the depo-
sition of the galena. This fracturing
permitted the easy circulation of me-
teoric water, but the persistence of
the oxidized ores far below the ground
water level can not be attributed to
mere permeability Of the vein, but
must be the result of some physio-
graphic evidence outside the area dis
cussed in this report shows that the
Occur dAlene river was in pre-Mio-
Gene time several hundred feet below
its present level and the ground water
level of the area adjacent to it was
lower. During Mo
Gene time great lava flows damned
the stream and later during Pliocene
time, large accumulations Of glacial
debris filled the channel; since then
neither the stream nor the ground
water level has ever regained its for
mer position. With regard to fault
ing there is no supporting evidence
that the shoot of oxidized ore on the
hanging wall of the fault had been
displaced 1000 feet or more and thus
preserved from erosion. The vein it
self is displaced only so feet, and the
massive quartzite beds on either side
Of the fault plane show little evidence
Of great disturbance.
The large siderite veins in the
southern part Of the Pine creek basin
are oxidized at the surface, but on
account of their meager development