The copper era., 1907-03-28
Loss in Placer MINING.

A1IST 1OllOMlnS IHS OuSluSSS VI
hydraulic placer mining for more
than a quarter of a century, and
after giving the business all possible
study and attention, 1 am prepared
to say that the placer mines of this
country are losing 60 per cent. of the
total values carried by the gravel,
through the really crude and incom-
petent methods employed. This idea
as to the loss of placer gold is not
altogether original with me- =. 1 first
read it several years ago in the
literature of the Bennett Dredging
company of Denver. They stated
then, as fiat proposition, that the
mines, both quartz and placer, were
not saving over 40 per cent. of the
values, and they backed up the state
ment with proof that could not be
disputed. These people asserted
that the pan is the best saving de-
vice; after the pan comes the rocker,
then the sluicebox fed by the pick
and shovel, and last of all, or most
wasteful of all, is the hydraulic sys-
TEN.
The Bennett people made the claim
at that time, and 1 have later found
by practical test and actual ex-
perience that they were right, that
the only way to successfully save fine
gold is in dead water. l am CON-
vinced that, by present methods, we
are losing very large percentage of
fine gold and nearly all the platinum.
If the pan is the best saying device
and we catch no platinum in it when
we pan the sands of the diggins, is it
not reasonable to believe that we
lose nearly all of it in the sluice
which has boiling rifles with current
swift enough to sweep out the heavy
body of detritus?
The various character, compost
tions and occurrences of placer gold
in west coast gravel deposits are as
follows:
! l. Gold in nuggets, grains and
pieces of various size, but perfectly
free, so that it is readily recognized
as gold, and easily saved in the
sluices.
2. Gold coated with ruthenic acid,
has a reddish copper color; it is
called "rusty gold' by the miners,
and because it does not easily ANAL
o-,,,o+a 80 not nc a,e;l,, eovad - +ba
free nuggets.
3. Gold coated with osmic acid,
has black or brOwnish color, and is
usually mistaken for iron.
4. Gold in combination with palla-
dunn, has light gray to dark gray
color, and exists always as very
fine powder; it amalgamatesa at times,
but is destructive to the amalgam.
3. Gold in combination with
rhodium and copper, and called
''rhodium gold;" it does not ANAL
gamate.
6. Gold combined with bismuth;
has a silver white color, metallic lus-
ire and is often mistaken for plati-
mum; it amalgamates, but is also de-
structive to the amalgam.
| Z. Gold in combination with iron
or manganese, or both; has a brown
ish color, and is easily considered to
be iron.
The various combinations and oc-
currences of platinum in placer gray
els are as follows:
L. Platinum in fiat grains, known
as iridosmium. This combination
contains about 81 per cent. of plati-
mum, with gold, copper, iron and con-
siderable iridium and osmium.
/ 2. Platinum in fiat Illuminated
peices, known as sperrylite; contains
a high per cent. of platinum, and is
often magnetic.
3. Platinum in combination with
titanic iron and chrome iron: this is
the combination called ''black sand, y
and exists to very large per cent.
in our placers.
4. Platinum in very small quanti-
ties in the form of an inky-black
powder, which is a ruthenium sui
phide.
5. Platinum with native iridium.
The question is: "How can we
save these values?" OF course we
cannot save them all, but we can
certainly save more than 40 per cent.
of the total, which is all we have
been doing in the past, and all the
most of us are doing now. We
should sage fully so per cent. more
gold than we are now saving, and at
least small percentage of platinum.
DIR. David T. Day has demonstrated
1 that these values can be saved, and
if he can save them with the imple-
ments and methods he uses, we min
ers-can certainly do the same. He
demonstrated and proved, and [ have
convinced myself that it is true, that
to save the fine gold and the plati-
mum values they must be screened
through the bottom of the sluices
and allowed to settle in dead water.
That is all there is to it. To employ
a rifle that boils, as nearly all the
placer miners do, is to employ d
method that simply drives fully 90