Deseret evening news. [volume] (Great Salt Lake City [Utah]) 1867-1920, 1903-07-01
ON GEOLOGY OF
BEAVER COUNTY
Technical Treatment Of Subject by
Henry N, CrOwtheL
LITTLE HAS BEEN WRITTEN
About the Formations OF Copper re-
gion in This maaner Heretofore
Has Great Possibilities.

4 Mining Journal Henry NJ. Crowther,
the mining engineer, Of this city, con-
trlbuted an article treating on the cop
per deposits Of Beaver county, Little
has been written and published bear
ing-on the geology of this important re-
gIon, hence the News gives space to
TWAS follows:
Copper Mountain, 1900 It, high, at the
southern end Of Beaver River range,
Is prominent peak Of white limestone
forming the crest OF the and sur
rounded by deposits of copper ores as
yet but little developed. -Four miles
south OF Copper mountain, and at the
base Of IT, are the main copper mines
Of the region.
In structure probably three-fourths
Of the range Is composed OF eruptlve
rock This fact renders the study of
the region difficult, for the original up
lift was accompanied by intrusions at
successive periods, Of lgneous rocks
leaving but island-like masses Of sedi-
mentary strata in sea Of geological
confusion.
The igneous rocks Of the region in
clude monzonites, rhyolite, mica and
augite, andesite and dlorlte; Of these
rocks the monzonte varieties mem
toned seem the most closely related TO
the copper naturalization.
Copper Mountain and Rocky Spur
show evidence Of being the opposite
limbs of an anticline with a subsidized
crest between, though great erosln and
subsequent disturbance have combined
TO bring about the conditions as they
are al present A true granite forms
the core of this fold and appears at
surface towards Copper Mountain.
The sedimentaries remaining are Of
the Paleozoic series, Cambrian quartz |
tie and Carbonlferous limestone pre-
dominate, The limestone occupies the
most elevated position, with quartzite
next and the monzontes the lowest |
Excepting the granted This rule |
holds good In nearly all instances, and |
as the copper naturalization occurs In |
or near the monzonites, the copper
mines OF necessity occupy the lowest |
ground adjacent to the quartzite or
lime.
Thermal spring activity has been
general, large surface crusts Of porous
caloite several feet thick exist; cement
alton by iron water is also common,
making masses of lron-cemental brec-
ella but the flow OF copper waters IL
clearly apparent In few instances on |
iy,
The ore-veins are OF three distinct +,
kinds; /. Fractures wholly contained |
IN ingenious rocks. 2 Shear zone ifs |
alf.,,a
3. Typical contact deposits, mostly In |
lime, with or without porphyry wall
The first variety are generally con-
tanned in the monaonites and are fairly
persistent, they appear TO be filings |
along fiat thrust-planes rather than
mere vertical contraction cracks or fs-
sures caused by the cooling and shrink
Ing Of the once plastic rocks, The
feature OF these veins Is that OF second
airy ores Of copper and seams Of born
ite al surface. also considerable calcite
associated with the quartz gangue.
There are hundreds OF acres Of this
rock profusely scanned with copper
minerals In joint planes, large masses
OF which carry about ! per cent cop
per. with an occasional fracture vein
with 40 per cent to 60 per cent Dip |
containing from few inches to sew
eral feet Of copper ore. These veins
occur In parallel series with northeast
and southwest strike. The particular
belt Of mineralized material lies be-
tween the other two varieties of veins,
and Is over half mile wide az proven
20 date Its strike is east and west,
and II IL somewhat stratifled, With fiat
dip TO the south,
The second class OF veins are best
illustrated In the o. X, Blue Acre and
other deposits. These show no sui
phldes at surface, but have exposed
masses best expressed In acres, OF cop
per carbonates In blue and green
spotted ores in an lgneous gangue,
with quartz and sparse iron filling.
These deposits are usually overlaid by
massive quartzite containing much OK
idized iron at surface. They show up
thrust movement The strike Is a little
south -ot-West and north -of-east. The
fssure dips 20 the north though the
ore bodies are In the f0otwal Of the
fissure; because, no doubt the quartzite
resisted metasomatic action. Lacc0lite
with subsequent denudation
OF everything strata would account FOR
this class Of deposit
Caves OF underground caverns caused
by dissolution Of country rock, which
were partly rehlled with oXdized pro-
ducts Of iron, copper, etc, exist a
beautiful one was found in the O. X.
mine at 1870 IT. depth
The third variety OF veins " eXem-
pli0ed In the Montreal property, where
there Is q mass Of chrystalline calcite
impTegnated by copper Mineralized |
jasperod also magnetism siicates (ab-
rous tale or asbestic MATERIAL all con-
copper, are features of this
belt
The region Includes q great extent OF
most promising lime-contact as yet
uneXplored, some OF which contains
lead ores
Bodies up TO IS It. wide Of peacock
copper ores. averaging fully 40 per cent
roper with So. 50 IN gold-silyer per ton
as mined, have been opened up in the
o. r. mine, and the average ores Of the
region may be stated at 6 per cent
copper In mining 9 per cent ore there
will be developed a large tonnage Of 2
10 3.5 per cent ore which under normal
conditions VIII AFFORD a concentrating
as silica Is largely IN excess I
Of the iron content. The fact that the
sres generally contain gold and silver =
values enough TO defray the cost OF
the copper Is Significant The
gold value OF ores Is somewhat IN eX-
,ess OF the silver. The horizontal axis Z
" the ore shoots is generally greater
than the perpendicular.
Oxidation Of ores in the larger de-
,osts is complete down to 100 H.. where
he zone Of secondary enrichment be- q
rims, as marked by bornlte and chal-
;ocitc, the copper carbonate oreshow-
,ver, continue TO az least 400 H. IN
conjunction with the sulphides, The
carbonate ores contain but little iron.
lilicates Of copper are not uncommon,
while some native copper exists. but il
q not an important ore Arsenic and