The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1916-03-23
SAVING FINE GOLD ON
BARS OF SNAKE RIVER
MOST SUCCESSFUL METHODS DE.
scRIBED BY SURVEY-ARE
MANY FAILURES.

Some gravels contain gold so fine
that only small amount is saved
The gold from the Snake river allu-
vial flats in Idaho is 945 parts fine and
the particles are SO small that it takes
from 1000 to 1000 colors to equal one
cent, according to ]. M. Hill in bulle-
tin 620-L of the U. S. geological sur
vey. The largest pieces of gold are
scarcely DOL inches in diameter, while
many can only be distinguished by a
high power microscope. The larger
flakes are cupped. Most of the gold
is bright yellow, but some is red
brown, due probably to coating of
iron hydroxide.
Along the course of the Snake river
can be seen the wrecks of numerous
attempts to extract the fine gold
from the gravels. The remains of
dredges are seen here and there, and
many more have been removed. Count
less process machines have been tried
there, but so far as known without
success Most of these machines have
depended on amalgamation, but many
different methods have been used to
get the quicksilver and gold into con-
tact
The rocker and sluices are still used,
and sluice Of special type, known as
the burlap table, used also on some of
the dredges, has proved one of the best
appliances for saving the fine gold
The heavy sand and gold are caught
by the rough surface of the burlap
and the light sands run to waste. In
some places the failing Is rerun. In
operation the tables are cleaned as
often as necessary, by taking up the
burlaps and washing them in tubs of
clear water The concentrate, together
with that washed from the bottom of
the tables, is either placed in a grind
ing pan or revolving barrel for treat
ment with quicksilver and weak cyan
ide solution, or cleaned with rocker.
The latter method, while attaining
somewhat better results than the sim
pie rocking of the gravels, is not eff
cient. In some of the burlap tables the
first section of the table-that nearest
the Launder sluce-has a silver plated
copper bottom coated with quicksilver
for amalgamating the gold. The num-
Der Of tables varies with different con-
ditions. In some places all the tables
are on one side of the main sluice. In
fact, each operator has his particular
design of table and method of handling
the gravel.
Both suction pump and bucket
dredges have been used for lifting the
gravels. Probably the most success
full dredging operation on the river
was the Sweetzer- Burroughs dredge,
which was operated 30 miles west of
Minidoka. The first boat built by this
company, in 1894, was Of the suction
type, but the company later construct
ed bucket dredge having a capacity
of 1000 cubic yards a day. Concentrate
from burlap tables was amalgamated
in barrels. 1t is estimated that the
cost of handling the gravel was from
As to 55c per cubic yard.
Within the last few years expert
ments in cyaniding the gravels Of the
Snake river, while not financial sue
cess, have at least shown that the
method has merit. At plant 16 miles
southwest Of Blackfoot, the gravel was
screened through a 3-16 inch mesh
ed no difficulties were met with in the
teaching watts.