Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-12-09
Second Preliminary Report on In
veStigation of Black Sand.

DIR. David T. Day of the United
States Geological Survey, who has
spent the past summer in investigating
the black sands Of the Pacific slope,
has submitted to the director of the
survey second preliminary report on
the progress of his work.
The first report contained an account
of the minerals found in the various
samples of sand.
The second report reviews the ex-
periments in concentration that have
been conducted at the Lewis and Clark
Centennial Exposition at Portland, Ore,
with the view of ascertaining the most
economical means of separating the
useful minerals already enumerated in
the first report of progress. Expert
ments have shown that the sands of the
seashore and the sands from sluice
boxes and placer mines have been ar
ranged or classified by the action of the
water. The size of each grain of sand
is, therefore, inverse to its specific
gravity; that is, the less its specific
gravity, the larger the grain of sand.
1t has also been shown that machines
of the Whitley type do very effective
work in further separating these special
mixtures of grains of sand. Two sharp
conclusions have been established: D
! That 80 to SO per cent of the precious
metals, gold and platinum, are obtained
in the first inch and half on the sur
face of Whitley table; ~ that more
than ton of concentrates is obtained
for every 100 tons of sand passed once
over the table.
1t should not be supposed that the
enormous values per ton that are fire.
quently shown in these results mean
new discovery of that much gold where
it was not before suspected. This is
not the case. Gold was known to be
there, but no successful method of ex-
tracing it had been devised, and it
normally went to waste.
1t became evident at an early stage
of the concentration experiments that
the sands could be y separated very eff
ficiently on concentrating tables, such
as the well known Wiley concentrator
or the Piider concentration, the Wood
bury modification of the Whitley table
or the new type of concentrating table
recently developed by Mr.. Christensen
and used for the first time in these ex-
periments.
1t is well known that the minerals
most easily concentrated on such tables
are those which have been first put
through hydraulic classifer, device
which has the effect of putting together
large grains of light minerals and small
grains of heavy minerals. It was found
by examination of the sea sands under
investigation that wave action had a.
ready classified them, as described
above.
1t was also found that the action of
these sands in the same way, and the
sands which sluice boxes had failed to
separate were best suited for separa-
ton on the concentrating tables. This
investigation has therefore shown that
sands which can not be separated in
sluice boxes can be separated by me-
chanical devices more easily than can
ordinary gravels. From 95 to SO per
C mt of the gold and platinum contained
in the bleck sands are concentrated
wishin ? s.)ace Of an inch and half, or
less, on the upper edge of the concent-
rating tabln.
sub Il salts hal also lem obtained
in work along the same, dire ction by
Mr. Henry E. Wood, of Denver. These
results in concentration have been APP
piled in the exami istion Ct the beach
sands On the Oregon side Of the mouth
of Columbia river.
A lot of ore-half ton of the sand from
the beach, ;'bout nila Cue west of
Carnshan station was fed to three of
the concentrating tables and divided
into concentrates and tails. The ori-
ginal concentrates obtsined were run
over the tables again and reconcentrat-
eG. TIE first 1 IL inches of the mater
all as spsead Sit- on the table were di-
yided of IS No concentrates. The
ffext o. + inches were taken as No. 2
concentrates, ard the remainder went
as tsiIings. Tie concentration of the
gold and plaii:'nm thus effected is shown