The Elk County advocate. [volume] (Ridgway, Pa.) 1868-1883, 1875-12-23
MASSES OF COPPER.
How Mass Copper Is Mined---The Difficult
ties Attending the Work.


How Mass Copper is nIined---Tho DinicuI-
ties Attending the Work.
The largest continuous mass of copper
which has been taken out of the mines
of the Lake Superior region was proba-
bly, that from the Minnesota in 1857,
which is variously stated as weighing
420 tons and 47O tons. Its length was
about forty-five feet, its breadth or
height twenty-five feet, and its greatest
thickness eight feet. All such masses
are very irregular and ragged in their
form and thickness. thinning out gradu-
ally from foot to few inches, and
struggling through tho vein until they
connect with other large masses. This
was the character of mass found i'll
the Phoenix mine, one of the oldest on
the lake, which mass altogether weighed
some six hundred tons. But this was
really a series of masses more or less
connected by strings of metal, yet no
one large part of it weighed, singly, over
two hundred tons. A similar series of
masses, weighing about six hundred
tons, was extracted from tho Minnesota.
! Some of the Phoenix masses were fonr
or five feet thick of solid copper. The
Cliff mine has yielded masses weighing
from one hundred to one hundred and
fifty tons in one piece. One of forty
tons was taken out this year, besides
numerous blocks weighing from one to
eight tons. This mine and the Central
are now yielding mass copper in abun-
dance.
1t is of course impossible to pick, or
to drill, or to break out such huge mass
| SNf ga1iI ,,,atnI x,l,np fha,,
| by drifting upon the course of the vein.
The method is as follows: The miner
picks ont, or excavates, q narrow passage
or chamber upon one side of the mass,
laying it bare as far as possible over its
whole surface. 1t is usually firmly held
by its close union with the vein stuff, or
by its Irregular projections, above, be-
low and at the end. If it then cannot
be dislodged by levers, the excavation of
a chamber is commenced behind the
mass, and this excavation is made large
enough to receive from five to twenty OF
more kegs of powder. In one instance,
in the Cliff mine, charge of twenty-one
kegs of powder threw down two huu-
dred tons of copper. Bags of sand are
used for tamping, and the drift is closed
up by q barricade of refuse and loose
dirt. After such blast the drift is, OF
course, charged with foul air, and it can.
not be safely entered for hours after.
wards. If entered too soon, men lose
all strength in their limbs, and fal
down.
The huge masses of copper dislodge6
i'll this way are too large to be handled
and got to the surface. They have to be
cut up. The copper cutters are called in
and the mass is marked off in squares Oh
blocks of suitable size. Copper cutting
is distinct art, and requires considera
BILE skill and experience. Ordinary min
ers, however skillful they may be, can
not cut up copper without long training
The tools are simply narrow chisels
and striking hammers. The chisels are
shaped like the parting tools of turner's
They are made of flat bars of half incl
steel, about two inches wide and eigh
teen inches long. They are chamferet
each way like a cold chisel, to form tn,
cutting edge. This edge is made littl,
longer than the thickness of the bar
The cutter holds the chisel and two mel
strike it. A thin slice or chip of coppe
is i'll this way cut out in a narrow chan
mel across the mass of copper. Th
operation is repeated until the marrow
out, but little over half an inch wide
has been carried through the mass Th
chips cut out in this way are long, mar
row strips of copper only about half a
long as the groove from which the,
are taken, the metal being condensed
and thickened 10y tho force of the blow
This work is necessarily slow and te
dious, and it costs $12 per square foo
by contract. At this price, the cutters
, make 22 per day.-,Scientifc american