The Salt Lake tribune. [volume] (Salt Lake City, Utah) 1890-current, 1906-08-13
WORK ON MIDWAY
MINE AT TONOPAH
Discoyerer Decided to Pene-
trate Andesite Gaping to
Get at Resources.
MUCH ORE SHOWN
AS RESULT OF WORK
Description Given of TonOpah
PrOperty's Ore Bodies and
Vein Matter.

Several Of the men who had been in
the Tonopah district almost from the
| discovery-in fact, the discoverer, Jim
Butler, among them-decided to sink
| through the later andesitic capping In
the Midway mine, which outcrops at
the surface and prospect the underlying
earlier andesite for combinations Of
| the veins which outcrop to the south,
| where the ore originally was discovered,
says the Engineering and Mining Jour
nal. Work was begun October 23, 1902,
676 feet deep. Ore was found at A
dept hof 500 feet in an east and west
vein which dips about 40 deg. to tho
south. Since then ore has been found
in two other veins.
The south vein is from four to eight
feet in width, and averages about $35
per ton, the ore running from $50 to
ore is oxidized ,and is of milling char
acter, rather than n shipping ore, In
the footwall Of this vein, and about
seventy-five feet from it, another east
and west vein WAS subsequently, discov-
cred. This vein is nearly vertical, but
leans slightly to the north The ore is
sulphide 1t is upon this vein that
the present value OF the mine depends
The vein varies from four to twelve
feet in width, and is very rich. In
some places it has averaged over $1,000
per ton across the breast twelve feet
wide. For sixty feet, on the west side
Of the 435-foot level it was from SIX to
twelve feet wide and the ore averaged
over $500 ton as IT was shot down IN
the stope.
Much Assaying Needed.
About $50 feet south of the sulphide
vein on the 435-foot level another par
oil al Il ,tn 1xr 10 fla n,,yh
has been opened. The ore is about two
feet wide, and averages S75 per ton.
The crosscut on the 435-foot level has
been extended still farther, and is In
another vein, which dips to the south.
All these veins have a silicious gangue,
and occur as 11ssure veins in the earlier
andesite. Only the first vein struck is
oxidized; in this the oxidation extends
as far down as the vein has been traced,
i. G., to. the 535-foot level. Very little
can be told of the value Of the oxidized
ore except by assaying it; but when
the ores are sulphides, the richer can
be told by the amount OF visible sui
phidcs. However, ore which goes $40
to $50 ton often does not show any
indication of its value. Consequently,
constant assaying Is necessary to keep
track Of the ore in this mine.
The shaft, as said before, is 5x9 feet,
outside the timbers, and is timbered
with 6x6-inch Oregon pine sets placed
at five-foot centers. The shaft is di-
vided into hosting compartment 21@x
feet, and ladder and pipe compart-
mcnt 4x31a feet, Two-inch planks,
placed vertically, are used to lag the
SO the sets are only put in to hold tho
tagging. This shaft cost $l3 to Sl4 per
foot, most Of the work being done when
supplies were very high. It cost $3.50 |
per foot for timber, which then cost |
$50 per 1000 feet, instead Of $37, as at |
present.
sulphide Vein Opened
The sulphide vein has been opened |
for about 400 feet on the 365-foot level, |
and averages about three and a half |
feet in width. A series of raises has |
been put up on the vein to the Gaping
about six feet above, which cuts the |
vein off. The sulphide vein is 800 feet
long on the 435-foot level, and averages
about nine feet in width. The sulphide
ore body occurs in a series Of step |
faults, of which there is one between |
the 800 and 435 and two between the
435 and 535, These step faults are al
ways toward the north. Whether there
are also step faults in the other veins
has not been determined as yet, they |
being very little developed.
hand, single jack work being used.
A man can drill about eight feet per
shift in the porphyry and four to five
feet in the quartz. 4 method Of mining
somewhat similar to that used at the
Campbird mine, Ouray, Colo, will he
used. A line of strong stulls will be
placed over the tracks on the main and
levels to roof them over
The ore will be broken down upon
floor Of two-lnch planks, laid on canvas
so as TO catch the fines. The Slopes will
be filed with waste run down from
above, for owing TO the richness Of the
ore it could not be used to fill the slopes
while mining out the ore. Stull chutes
and manways will be carried up through
the waste filing. The mine has been
connected with the Montana -Tonopah, so
that it is well ventilated
The company employs about forty
men on the two shifts. and ships about
LOO tons of ore per week, which goes
from 500 to 5000 per ton, about two
thirds of the value being silver and one.
third gold. Many shipments have aver.
aged over 5000 per ton, and one ship
ment averaged $500 per ton. The com
pany has shipped approximately $500
tons of ore so far.