Eureka daily sentinel. [volume] (Eureka, Nev.) 1871-1887, 1882-10-08

Description. Scientific and Practi
cal, of q Great Mine.

Bertrand mine is simple in its nature, the
main mass of the hill being formed of an
underlying bed of porphyritio granite,
which is capped by transition strata Of
silicious limestone and followed upwards
by heavy beds Of crystalline metamorphic
limestone. This hill, from its evident
connection with the other mountains of
the region, is the eroded fragment OF q
fold or mountain uplift. The strata OF
which it is composed are submarine in
origin. Geological evidence is that these
strata were lifted from their submarine
position at the ~triassic period and folded
into mountains, and permanently raised
above the level OF the sea; in fact, at that
time they reached their present altitude
above the level of the Pacific. This great
uplift caused by this igneous rock pro-
duces two great effects, the metamorphism
of the strata and the assuring of the
strata resulting in metallic mineral veins
or lodes.
A CONTACT LODE.
Tho Geddes & Bertrand mine is a con-
tact lode, the strike of which is N. 80 de.
grees w. aud s. 80 degrees E., and dips at
an angle of As degrees to the southwest.
Upon entering the mine fifty feet below
the surface we find ourselves Immediately
surrounded on all sides by ore, and fol-
lowing the workings downward for mere
than three hundred feet it is a continuous
mass of ore. This great ore body is COM
posed OF three recognizable zones that
next the country rock or silicious lime
works about 500 to the ton; a CEN
trail zone containing much oxide of iron,
the matrix of which is heavy spar or
baretta, is the low grade ore of the mine
and works about $50 to the ton; the I'M
derlying or third zone next the porphyry
is more silicious and consequently the
richest. At two points in the workings
downward through ore perpendicular to
its general inclination We come upon a
surface of ~porphyry which, i'll my opinion,
is the definite foot wall Of the lode, and
that in wo other places in he upper de-
velopments of the mine we come upon
broken surfaces of limestone more or less
in their surface, more or less
impregnated for a little with punches and
.stringers Of ore, which | take to be the
rough hanging wall of the lode. The so
foot chamber contains a mass OF ore from
60 to 70 feet wide and continues downward
from within two or three feet of the surface.
On this level a new body of ore was re-
Gently discovered. At the present writing
it is 90 feet wide and eight feet high. AS
the workings progress it attains larger
dimensions. The strike of this new find
is to the northwest. 1t works S110,
some of it assays as high as $3.50.
Niuety-five feet from the surface another
-~. - ,.. 80, 1trnnyArn1
AN IMMENSE DEPOSIT.
Since the company purchased the prop
erty this bonanza, 50 far as develop. d, is
more than 100 feet wide. This appears at
the present time to be distinct and sepa-
rate from the main ore body, though at
future time it may connect. On this
level a large body Of quartz is encoun-
tered containing gold and silver. As
depth is attained this quartz lode will be
found connecting with the porphyry foot
wall and continue downward as the true
lode of the mine. Very rich ore is found
top Of this quartz lode. On the 49,
foot level we find ore $50 feet wide, and
this only so far as developed, for no walls
are as yet encountered. In ascending
from this level, about thirty feet to the
south, we get into the foot of Chamber
No. 5, where ore is found to be nearly
200 feet wide Of the same quality and
character as in the 150-foot level. This
appears to be the working leve lof the mine.
ore broken out above is sent down by
chutes to the 150-foot level, then run out
to the main shaft and hoisted to the sur
face. The mine is well ventilated and
connections are bsing made from the diff
ferent levels to the several ore bodies.
Work is about to be resumed in the lower
workings Of the mine. There are two
wines sunk in the ore connecting the
workings with the 150-foot level.
is known of the size or dimensions
of the ore bodies in the lower workings,
as no work has been done there since the
purchased this property. A
six and a half by five and a half
feet and about /, 200 feet in length is be-
ing driven from the mill to strike the 100
foot level, the main object of which Is to
through it all ores from the
mine. The working Of the mine ia pros.
with intelligence and ability, and
the property is capable Of vast develop
ment.
A VALUABLE COMMERCIAL PROPERTY.
If the commercial value OF a mining
property depends on the quality and guam
tity of the ore that can be obtained OF a
given tenure Of the precious metals, then
this mine is bound to nave a great COM
mercial value. Hundreds Of thousands OF
tons are now in sight. Here is a contact
lode Of great length and it goes down to
the source of the plutonic rocks, or as far
as the ingenuity of man can contrive to
work it. The extensive explorations dem
the existence of a magnificent ore
supply, carrying a large average tenure in
gold and silver. After long, careful and
costly experiments the reduction of these
ores by the teaching process has proved to
be a success with q good margin OF profit,
and this important fact rests on no labor
atory tests or theoretical opinions. 1t has
been demonstrated by r. D. CLARK IN the
mill at the rate Of from forty to sixty tons
per day for the last three months. The
cost Of running the hosting and pumping
machinery is about the same whether
twenty or one hundred men are working
in the mine. The anne, to a less extent,
is true in running the mill.
JOHN NJ. FOLEY.
Secret Canyon, Eureka County, New,
Oct. 6. 1882.