White Pine news. [volume] (East Ely, Nev.) 1920-1923, 1923-04-22

vertical fractures meet.
A small vein OF iron pyrite was
found, "a inches wide, dipping 80
degrees southwest, protected both
above and below by a thin seam OF
hard hematite. This pyrite vein
yields 6.5 per cent copper. 1t shows
no sign of ~chalcopyrite and only once
has the latter mineral been found in
this zone. Following is a partial
analysis of ore taken from different
orebodies above and below the tun-
mel: Gu, 6 per cent; Fe., 80; insol-
uble, IS; Mn, Is; Gao, 4; Au. and
Ag., 40.
There is no regularity In the diff
ferent occurrences of ore found in
this limonite mass, but further work
may connect all or several of them
In the present zone.
Raises in ore from the tunnel
demonstrate that the ore is within
ninety-five feet of the surface. Fur
Their work may find that the orebody
continues upward.
This particular iimonite zone oc-
ours in the hard blue limestone of
Nevada so familiar in this district.
By referring TO the geological map,
the work of Professor G. W. Young
of the University of Nevada, two dis
tinct porphyry masses may be noted.
This porphyry bears no resemblance
to the ~orebearing porphyry found In
the center and the west part of the
camp. 1t is Just as hard on the sur
face as in the mine and nowhere
does 1t show any sign OF disintegra-
ton. II is described by Spencer as
follows: '.These masses have not
suffered the same thorough meta
m%orphism that has affected all the
p%orphyry bodies farther west along
the principal ION of intrusion, but
the rock exhibits incipient stages OF
alteration and contains more or Jess
pyrite."
This rock Is quite distinct from
anything found in the district, hav-
ing large crystals OF pink orthoclasse
and a liberal quantity of hornblend.
The mica group is absent.
In no place has copper been found
in the porphyritic mass excepting at
one place on the surface, where cop
per is found adjacent 10 an iron vein
leading directly to the limonite zone.
1t is therefore doubtful If the por-
phyry has been responsible for the
copper contents of the limonite ex-
cepting that it tilted or crushed the
Ifvv1 aCtnnA oII1 rufae- Al, sa1w-ls-..
agent to deposit it's contents direct.
This argument is aided by tire fact
that the usual lime contents Of the
limonite is never over four per cent,
with small quantities of aluminium
and manganese, as found In the fore
going analysis.
l will take the liberty of quoting
Professor Young In the matter of
limestone deposits contiguous to in.
trusiyes: Lawson does not spe-
officially mention any work upon the
deposits in the limestone contiguous
to the intrusiyes. From this 1t could
oo reasonably argued that the pres
,ence Of the 'orebearing porphyry' is
a necessity for the occurrence Of cop
per ore in any given area In the
area examined this ~'orebearing por-
phyry is absent, or il present is only
so in small quantities, and this would
cause the area to be looked upon IA
vorably. However, the writer is OF
the opinion that the occurrence OF
ore is not limited to the 'porphyry'
and gives as his reason the examples
afforded by the Clifton-Morencf and
Bisbee districts, both OF which pre-
sent analogies to the Robinson iis-
trict. Az both of the above Localities
valuable copper deposits have beer
discovered in the limestone and met
amorphic rocks close to igneous in.
trusions."
The limestone zone above referred
to is found at shaft No. l and in a
northeast direction from this point a
number of small pits are located al
most in a direct lire. All of these
pits yield limonite and copper and
probably indicate a assure which nav
lead not only to additional zones OF
the same character but in all prob
ability Is the connecting link between
all of them.
For the purpose of further explo~
ration a shaft mo. p was started
40 feet north of the present zone.
From the surface IL has yielded COM
mercial ore to a depth of 1914 feet.
Here a crosscut was driven east
under the above mentioned line OF
Groupings and c~rystallized limestone
vas found for a distance of eight
feet. Since we had proven limonite
in the footwall of the shaft we had
n right 20 expect that Il crosscut nm
der the line OF fracturing TO the east
would open up the zone for which
we are exploring.
A westerly crosscut was driven.
having limonite and yielding copper
for a distance OF Nsevonteen feet. This
serves to illustrate the erratic nature
of a limestone deposit and shows that
this rome flattens on. toward the