The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1896-04-19

at the head OF his profession, but also
as a practical miner, recognized for
his ability wherever his name is known
Mr.. Robinson describes the mineral
bearing zone of the district as follows:
The rock may be characterized as
limestone, stratified and more or less
impure, interstratified with clay states,
sometimes called killos. These rocks
are recognized the world over as being
the most important gold-producers
when they occur contiguous to or IN
contact with the igneouS or primitive
rocks. This condition prevails at Mer-
cur, as the Oquirrh mountains are only
range Of high hills in the midst OF a
great desert country, formerly known
as the Great American desert They
might be characterized as Islands OF
sedimentary rock in the midst OF the
great pcrphyry area, which is about
100 miles in width from east to west
any many hundreds of miles in length
from north to south. Along the tanks
OF these sedimentary islands, parallel
ing the contact with porphyritic areas
are found some Of the most prominent
mines in the world that have been
worked continuously during the last
twenty-five years, and which have add
ed many millions 10 the worlds output
of precious metals.
THE Oquirrh range was formerly
sea-bottom; subsequent upheayaiS
caused the rock to form a great curve
or arch, with its major access north
and south, and the subsequent read
Justment Of rock masses has caused
many faults and folds in the strata.
IN the vicinity of the Mercur mine the
rock strata now lie nearly fiat, with
d general strike north As degrees west,
magnetic, dipping toward the north
east and having an inclination of IL
10 80 degrees under the horizon. The
great longitudinal faults of the coun-
try are formed in lines approximately
north and south, which is evidenced by
the escarpment exposure and precipi-
tous slopes on the west faces Of the
hills, with long, easy slopes leading
to the east.
PROBLEM FOR THE MINER.
such a fault appears to the east of
Aercur and the Golden Gate properties,
and is marked upon the surface by gen
eral depression. The collaborating. strata
viii in all probability terminate abruptly
on their dip in this fault, and If found
farther east will be at some different ele-
walton, probably at a higher altitude. The
strata the selves before reaching the
fault viii ne found upon constantly
increasing dip until it will terminate in
a vertical assure or faultng plane.
The problem that now confronts the
miner is as to whether the payable ore
bodies will continue to the east of the
11ulL, OF whether lleN VIII dSSuillS DIT
this point vertical position. Subsequent
10 the caving in of the arch, erosion has
secured out the raVines, exposing the ore
bearing strata along Its apex. This apex
is near the summit of the north and
south anticlinal, which is in evidence by
reason of the strata dipping both east
and west from its summit The ore
strata are exposed in many places upon
its flank and numerous faults and folds
have been developed.
THE mineralized zone or vein, as the
miners call il, is nothing more than
stratum of altered limestone, ranging
from six TO eighty-five feet in thickness,
measured at right angles to the stratum:
This is pretty thoroughly impregnated
with arsenic in the form of realgar ana
mercury or quicksilver in the form OF
cinnabar, carrying gold in varying guam
titles, ranging from trace to several
hundreds of dollars a ton. The apex, or
Neln is generally rather fiinty limestone,
which IS sometimes decomposed clayey
material of yellow-ocher color, winch US
ually assays from q. trace to IS a ton.
In some places in the ore-bearlnS
zone silica has been deposited as a re
placement-in other words, is pseudo-mor-
phic. ,o,o
the color being due TO the carbon con-
tanned This shale usually carries the
coal fossils and sometimes carries a. finely
disseminated iron pyrites, whlch Is not,
however. arsenical. The shale is very ifs
sile in character and contains enough
lime SO that when exposed to the atmos-
phere il quickly slakes away to clay
COLOR OF THE ORES.
.,'rhe foot wall OF the one is usually
hard crystalline limestone, but 1t is not at
all uniform. Great holes ana chal ilasls
are formed where mineral solutions nave
replaced the lime, and in these channels
The ore is generally of better quality than
is the general average of the whole mass.
., ORR Ia a
developed a thickness of twenty-1our TO
thirty feet and the average thickness
of the ore bodies may be placed at nlleeh
TO eighteen feet: The dlrecton OF me
foot wall channels may be stated as APP
proximately parallel with the local dip
OF the strata. The appearance OF the ore
IS yellow, brown. red brown, sometimes
gray or black, and the limestone itself,
when ii is colored, usually carries good
working values The payable portion of
the ore of the vein on the foot wall SIDE
can only be determined by assay, while
the hanging wall side is distinctly
From the above description it will be
seen that the vein in the Mercnr district
is not vein at all as the term is usu-
ally understood; a better name would De
an inter-calate vein-if il is a vein at
ali. 1t seems to me that better name
would be mineraliZed zone of country
rock The Germans, recognizing this
character of deposit, have given it the
name of 2 falkland meaning a rotten
stratum 1t is undoubtedly true that the
silica occurs as a chemical replacement,
and the onlv difference between the Mer
cur district and other localities farther
south is that in the Mercur district the
chemical interchange is as yet incom-
plete.
TAREE SEPARATE, DISTINCT ZONES.
TT is also true that in the Mercur dis
frict the payable values do not always
follow one stratum. There is evidence
that there are at least three separate
and distinct nnineralized zones. It is also
probably true that The whole area of
the country will not b underlaid with
gold bearing rock in payable values, but
that the shoots will assume definite
boundaries with a trend lying between
the walls in a definite and direct course.
As 10 what this direction is at the pres
ent time has not been determined.
There has been some discussion among
mining men as to the probability of the
ore-bearing zone at Mercur carrying with
II extra lateral rights. From the general
construction of the zone, and the fact
that there is hardly an instance in the
Mercur district where the letter of the
mining law has been strictly complied
with it appears to me that it will be
very difficult to enforce mining rights on
the dip of the vein outside of the vertical
boundaries projected. 1t does not appear
10 me that in the northern part of the
district there is a single instance where
the apex of the vein can be proved TO
have passed through the end lines of
the claims as located and staked.
,'As to the future of the district il is
probably true that it will develop in mag
tons Of its most enthusiastic supporters
The treatment Of many thousands of
those chronic weaknesses and Distress
ing ailments peculiar to females, at the