Douglas daily dispatch., 1928-01-29

known mining man, who has Just re-
turned from Mexico in an article pre-
pared for The Dispatch.
Mr.. Whiteside has been connected
in various capacities with the develop
ment or operation of practically all of
the big copper camps in the south
west At cne time he was underground
foreman at the New Cornelia in Ajo,
during that mines development Later
he was scouting engineer for the late
General Greenway Mr. Wl1iteSide
first went to Cananea "a years ago
and has a wide knowledge of that
section.
His article follows:
That the new Cananea ore body is
the most stupendous single body CT
hign-grade ever found on the North
American continent, is the opinion
among men in Cananea, who should
know
It isNkaown as the Colorado" mine.
The ore is primary chalcopyrite,
h0rnite and covellite, carrying good
gold and silver values.
In the upper levels it occurs around
a plug of quartz-porphyr intruded in
to the Diorite porphyry. eThere is a
tendency to call the latter rock Mon
zonite, but that is an infringement on
the Guggenheins.s They've got that
rock copyrighted).
This plug occurs in a break" or
fault fissure paralieling the Elisa
fault. but dipping in the opposite di-
rection-that is, it's the other side of
the uplift from which the faulted
blocks are doWnthroWn
There are at least two other breaks
evident. These are also parallel. One
dips the same as the Elisa and one the
same as the Colorado. These are in
ner breaks and disclose the deep-seat-
ed QuarEite, in the Mesa region
The rock column of the district, from
the bottom up, is Granite. Quart7ite,
limestone, and on top the Tufts with
intefbedded layers of Andesite.
Here's the geological story of the
district as I readsit after five months
Of work there: First, the uplift, then
the Elisa fault, then the Diorite por-
phyry intruSionS, then the main faults
paralleling the Elisa, then the main
crcSs-faults, most of which are ore
bearing, then the Quartz -porphyry in
truSions and least of all the ores OF
the Colorado and Duluth type of de-
posit The crosS-faulting and Quartz
porphyry intrusions may be practically
contempo mporane0uS and related
The Quartz porphyry intrusions
mark both the main breaks and the
crOSS-faultS.
7Thepores Of the great mines of the
past are supposed to have been asso-
all ea1r xxy;+ - y ~;
rite-perphyry intrusionS Quein5 Sabe?
The Duluth mine is on the Colorado
break; is faulted slightly to the north
and is at the intersection of cross
fault. It is of the Colorado type and
the ore is found around plug, prob
ably of Quartz -porphyry, though mark
ed as Diorite- -porphyry on the Era-
mons map. 9a
The Colorado may prove to be at the
intersection of cross-fault in which
the Veta Grande mine is located, but
it is almost impossible to distinguish
these faults when both sides are Cf
the same rock, in this case Diorite-
porphyry They are more readily dis
tinguished il the Mesa region where
the Andesite and Tufts are dropped
into juxtaposition with the Quartzite
In the Andesite and Tufts of the
Mesa region, the main, or kmaster
breaks" paralleling the Elisa fault
take the form of veins and seem to be
ore-bearing. Five years ago a shaft
being sunk on seven-foot vein, un-
expectedly dropped into a 2O0-foot
width of ore assaying 1.25 per cent
copper. This hit the Elisa fault
! 4 -
notable 0re-bearer. 1t seems to be a
parallel break" or a series of closely
spaced breaks, running through and
north of the Cobre Grande mine that
caused the ore bodies of the past and
not the Elisa fault. The strike of these
two faults is N. rs degrees w. dip N Il.
Extended on the map, the Cobre
Grande break runs into the Capote
mine.
Former data to the contrary, not.
WithStanding the true strike of the Ca
pote ore body is said to be N. rs de-
grees w. The Ricketts, and Capote
faults are cross-faults and intimately
associated with the ore deposition.
Southeastward after passing the
faulted blocksthe master breaks" are
back in their courses and straight as
a string; the Elisa, at the Gibbs-Pa-
tron property, the Cobre Grande, at
the Rayadora and the Colorado is un
der the Duluth Mesa.
The Cobre Grande break should do
much better than the Elisa in this re-
gion, and the Colorado should surpaSs
them all The bonanza ores of the
Elisa and Cobre Grande breaks were
largely due gto the secondary enrich-
ment of highly pyritic ores deposited
by hot waters. The Duluth and like
wise therefore the Colorado, break to
the direct injection of the ore magma
The primary sulphides are much more
apt to be commercial ore.
The altitude of the Mesa region is at
least 1900 feet lower than the collar
of the Colorado mine shaft. The re-
port is that on the 15OO-level the
porphyry plug is almost entirely re-
placed by ore Of good grade. This ap-
proaches the vein condition of the low
er altitude of the Mesa region.
The block under Ronquillo with it's
dead-gray tufts is faulted north and
downthrown by cross faulting perhaps
q Thousand feet TT iS this block that