Western news and the Libby times. [volume] (Libby, Mont.) 1920-1933, 1932-03-03
Rifles For
Saving Fine Gold
By Sidney M. Logan


The early native miners of South
America used blankets, hides with the
hair uppermost, grass sods and steps
cut in the naked bedrock as gold
gathering rifles. Later blocks, cobble
stones. 2x4s, 2x6s and peeled poles
came into use in California, Montana
and other places. 1t is long step from
these primitive methods to the gold
saving table of the modern dredge, the
steel rifle, the centrifugal and other
placer machines and the oil flotation
process
1t may be noted that considerable
work has recently been done IN an
effort to apply the flotation process to
the recovery of the gold from placer
concentrates. Anyone interested in this
subject would do we'll to write the
Montana School of Mines, Butte. Ex-
periments along this line have been
carried on by that institution this win
. ter. DR.. Thomson and his staff of ex-
perts would be only too glad to give
mining operators the benefits of their
researches and experiments.
The Steel Rail Rifle
The use Of this rifle was developed
by Pierre Bouery, manager of the La
Grange mine, Weaverville. Calf. This
mine on Trinity river was perhaps the
most important hydraulic operation in
the world. Its sluices were six feet
wide. A bank several hundred feet
high of 10 cent gravel was broken down
with giants and run through this siuice
at the rate of 1000 cubic yards per
hour. The giants and sluice disposed
of boulders up to two or three tons
in weight, Boulders larger than this
were bulldozed or drilled and shot
the pieces discharged through the
sluice
Importance Of Recovery of Fine Cold
Since fine gold is more widely
distributed than coarse and usually
represents the major values in any
alluvial deposit, the question OF its re-
covery is always Of economic irnpor-
lance Coarse gold especially, if it be
round or angular, generally takes care
Of itself. Given reasonably efficient
rifle, the proper grade Of sluice and
amount Of water its recovery presents
no serious problem
The recovery Of fine, flaky and flat
gold, however, is another question.
Owing to its lightness it is carried in
suspension in even slightly muddy
water It slides along longitudinal riff
files and crosses ordinary cross rifles
with facility
The steel rail. set at right angles to
the flow Of water and properly spaced,
is essentially a boiling" rifle. The
lower or down stream flange causes an
air space to form into which the fine
gold descends and finds its way to the
wooden pockets hereinafter described.
There it is held until cleanup time.
So effective has this type of rifles
been found to be that the bureau Of
mines reporting on the LAGRANGE mine
sponsored the claim that gold SO fine
that when dry it would float on the
skin or surface tension OF glass OF
water, was recovered The writer's ex-
perience with this rifle on Libby creek
convinces him that this claim IS fully
justified Not the least of its advantages
is its comparatively low cost of install
alton and its long life.
Bouery summarizes the desiderata in
rifles as follows:
Conditions in low grade deposit
require that the rifles shall:
"1) Oppose minimum resistance
to the movement of the material, I'D
resist wear; 90 maintain their saving
capacity at its highest point; (4) be
sufficient in number to recover all the