The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1914-05-07

Is indeed suggested by the behavior
of the mine waters, which evidently
circulate with much greater freedom
in the harder and purer quartzite than
in the softer and more sericitic rock.
1t is natural to infer from this that the
ore bearing solutions flowed through
the purer quartzite, which became i'm
pregnated by them because of its rel
atively porous texture. But this con-
cluson does not explain the fact that
a great part of the quartzite penetrGt.
ed by the mine workings. though ap
parently Identical in character with
the matrix of the copper minerals, is
nevertheless quite barren.
The bedding Of the Revett quartzite
in the mine and consequently the ledge
itself dip steeply south southwest.
few hundred feet south of the ledge,
on the surface near the workings, is
reversed fault whose general strike Is
east and west and which has a steep
dip to the north. The relations are
such that in depth the ledge is cut by
the fault, and the segment south of
the fault is relatively depressed
These structural features were
stated and illustrated diagramatically
by Ransome in the report that was
based on the examination made in
1904. Chiefly on the basis of the geo.
logic mapping, which was done by F.
c.. Calkins, the fault was said to be
between Revert and st. Regis beds;
its throw was estimated as not less
than 700 feet. and its dip was shown
as being such that the ore bearing
stratum would probably be cut off
about 100 feet below the level of tun.
mel No. 8.
1t now appears, from facts of which
some were overlooked and others in
accessible to observation in 1904, that
this description of the structure,
and open to some cumulative cor
rection The extensive workings on
the No. tunnel level which had not
been begun in 1904, show that the
structure is more complex than was
supposed and that the movements as
cribed to a single fault should rather
have been ascribed to fault zone, of
which the fault that was recognized
was the northernmost member. The
throw of this particular fault is prob
ably less than 700 feet, for the rock
on the south side of ii in the mine be-
longs chiefly to the upper part Of the
Revert quartzite rather than to the ST.
Regis, and the ledge has been found
on the No. tunnel level in a position
which it could not occupy if the guam
titative elements of the former inter-
probation had been correct
The recent denomination made this
much apparent; but 1t was not COM
plete, inasmuch as the weather pre-
vented review of the surface ex-
posures, and therefore an attempt to
interpret the structure in detail would
still be premature Even the down
ward course and the throw of the nor
, thernmost fault are still somewha,
problematical. The structural facts OF
chief practical Importance, however
are fairly clear from the exposures or
the No. 4 tunnel. Two segments OF
the ledge appear on this level, cut
apart by an east-west fault which
ha h.A h.,
, but if so, the general dip of this fault
which averages about 20 degrees abov,
No, 3 tunnel, must become vertical be.
, low that level. Another considerabl,
t fault, which brings st. Regis bed:
against Revett, is about 500 feet south
of the one just mentioned in the east.
fern part of No. tunnel level. West
ward It converges slightly toward tn,
other. Between these two faults arr
Others that strike more nearly nortl
.. and south, but the ledge is sufficiently
exposed to show that a large part o.
il south of the main Snowstorm faul
is unaffected by important fracture:
and could readily be opened.
The ledge, however, is not all com.
posed OF commercial ore. The portion
rich enough to work at profit-tht
ore shoot--has maximum stopt
length of about 100 feet. II has 8
J pitch Of about 30 degrees near the
surface, but this quickly changes to g
low eastward pitch. AS the strike OF
the bedding plane and main fault con-
verge toward the east, it follows tina,
the ore shoot is cut off at less depth
than the ledge. and practically NJ
commercial ore has been found below
the 900-foot level. The portion of the
ore shoot south Of the main fault. il
the shoot persists across that fracture
is presumably below the level of tun.
mel No t.
The element OF uncertainty implied
IN the last sentence is one that should
be frankly considered Although the
structural relations prove. that the
ledge is older than the faulting. il
. seems possible and has indeed been
suggested that the concentration that
produced commercial ore is later than
the fault, and that the ore forming the
shoot was deposited by downward
moving waters, which were damned
bN the fault gDuyp If this were trrle