The indicator., 1897-02-13
MINING DEPARTMENT.
SMALL PROFITS In THE MINING BUSHES
Value of State Geological Surveys Advantage of
Sinking Deep Shafts-Notes.

The Engineering Magazine for Feb
ruary has an interesting article from
the pen of Thomas Tongc entitled
Some Important Mining Tunnels in
Colorado. The article gives n clear
Idea OF the usual vein situation and the
necessity for tunnel where the
ground permits of its construction,
which can be readily understood by
the average Eastern reader who gener-
ally has but the crudcst notion of the
manner of operating II mine.
Another idea which has in some man
ner Obtained possession of the Eastern
mind is that gold is not only where
you find it. but that 1t is 10 he found
In profusion. j. T. Cornforth says that
most of the people east of the Missouri
Imagine that the sides of shaft are
plated with gold and the floor of solid
silver. Mr.. Tongc puncturcs this the
ory by showing on what a narrow
margin many of the great mining en-
terprises of Colorado are conducted,
and that some of the most profitable
mines have "A profit above expense that
in ordinary commercial undertakings
would be considered ruinous, the mag
nitudc of the tonnage and the most
careful management alone insuring n
profit. while the slightest indiscretion
IN the Items of expense in the engineer
ing department or In the judgment of
the superintendent will turn success
into disaster.
As an example of the careful man
agemcnt necessary he instances the
Revenue tunnel. through which the
Nirginius mine is operated. The total
length of this tunnel is $500 feet to
the intersection of the Nirginius vein.
Its greatest depth is 5000 feet. 1t was
completed in 1891 Mt a cost including
the water power and electric plants, of
100000. At the time of its compile
tion the workings of the mine had
reached n depth which greatly reduced
the profits Of the enterprise and had
the decline in the price of silver in 1893
found the Nirginius still dependent up
on surface hoisting machinery and
pumps the mine would have been com
PEELED to close down. The average val
ne of the ore is $50 per ton. which even
in these days of reduced charges for
operation and treatment would with
cut the reduction of expenses resulting
from automatic handling preclude the
possibility of profit. But the ore is
dumped from the cars into the top of
the mill and is then handled automat-
ically till the concentrates leave the
mill for transportation 10 the smelter
The capacity of the mill is 300 tons of
crude ore daily. which is reduced to
SIXTY tons of concentrates. worth 800
per ton. or daily output of $1,000, the
total output of the year being upwards
of S2,OOOUD. The figures seem large.
but when the enormous capital. energy.
skill and experience is taken into con
sideration the results cannot he re-
pur rIn ttn, n n.
as pointed out by Mr.. Tongc. is he
tween an expenditure of labor in hoist
ing and pumping which would wipe
out all the margin of profit and the ap-
plication of natural principles which
wrcst victory from nature at the very
moment of defeat.
The article is clnborntcly illustrated,
and is one of the best expositions of the
tunnel enterprises of Colorado. and in
cidentally of the business of mining.
that has been published.