The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1906-10-07

dred secondary products at greater depth,
whereas the deposits of Ely resulted from
the percolation of descending atmospheric
waters, containing in solution copper de-
rived from the decomposition of pre-exist-
ing Sulphide ore bodies which occupied
assures in the limestone stratum that
was uplifted by the intrusion of mon
zonite. Undisturbed portions of the most
important assures which contributed to
the enrichment of the monZOniteS are to
be seen i'm the Chairman group Of the
Nevada Consolidated company and in the
MaceO. Dauntless and Robust claims,
formerly the property of the Ely Mining
Milling company. now controlled by
Senator Thomas Kearns and David
Keith.
All that now remains, however TO mark
the western extension of these assures
are huge masses of brown irOn-stained
slhcious dry bone. strewn i'm heaps and
roughly parallel ridges upon the surface
of the monZonites. This substance once
constituted the insolubIe gangue of the
original ore veins. the limestone, the walls
of which have long since crumbled under
the erosion ard solvent power of meteoric
waters and their substance has been car
ried to the valleys and the ocean. leaving
behind the copper and precious metal
contents to build a new type of lode in the
intruded mOnZonite.
Value Easy of Recovery.
The solvent power of such waters upon
iron-copper sulphides is ample, but the
by, and hence we find the secondary de-
post of copper mineral in the Ely mon
zonites confined almost exclusively to
the joints and fracture planes of the rock,
fact, however, which renders the min
eral exceptionally amenable to recovery
by simple methods of concentration for
the reason that the mineral particles on
slight pressure readily separate from the
rock, without being subjected to the abra-
sive effect of excessive crushing.
This leads us to suggest that Mr.. Requa
greatly overestimates the presumed OBJ
StacleS that have heretofore prevented the
successful treatment of those ores.
wherefore. he invites investigation in the
field of Improvement, in order that a
more complete recovery of values NAV be
accomplished. On the other hand I think
he greatly underestimate or under-classi-
fies the grade and value of such ores i'm
the economy Of copper production of the
world For instance, the copper contents
claimed to exist in the Ely mOnzOnites
exceeds that of the average of all the
ores of the Lake Superior region mined
during the last forty years by nearly 100
per cent, and fully equals that of the
Calumet & Hecla mine which, during that
period. has paid in dividends nearly $780,
O00O 00.
The average yield of fine conner nor
ton of ore mined and treated from those
mines which have been profitably worked
during this period, at least during the
past ten years. cannot exceed twenty
pounds, and in one instance (the Atlantic
uliilct tHt dHuudi average mas fallen be-
low twelve pounds per ton, whilst the
average depths from which those ores
were hoisted probably exceeds $500 feet
Besides, the ore is extremely hard tough
and difficult TO mine and crush, and. al
| though the copper occurs in metallic
form, the recovery does not exceed 81
per cent of the metallic contents. and this
in a condition only about 6S per cent pure
and ii is therefore subjected to a snelt-
ing or melting cost of about s. per ton.
Cost Of Producing Copper.
The Ely are said to contain from
forty-five to sixty-five pounds of copper
per ton. The average recovery should.
therefore. not fall below thirty-five to
forty-five pounds per ton, and the result
ing concentrates should be smelted and
reduced TO electrolytic copper at cost
lot exceeding Sc or 81 per ton. The cost
of mining should be in ratio of at least
five tons of Ely to one of lake whilst the
cost of crushing and preparation for con-
centration should be even in greater ra-
ito in favor of Ely. and, finally the con-
centration of Ely ores, owing to the COM
parative low specific gravity of the gauge
chn he ar,1 &c IL H.