The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1918-03-07

dredge operator estimated that his
dredge has been losing IA ounces of
in more favorable ground probably
loses less, but the losses seem to have
been studied in detail at only few
localities. The limit in methods of
critical point where the cost of the
improvement offsets the increase in
returns. New methods or apparatus
must add TO the income or be aban-
doned. Where dredges must work
rapidly in order to handle a large
yardage the difficulties of making a
great output of metal are increased,
but the introduction of improvements
like the Jig and the elimination Of as
much barren material as possible from
the sluicing apparatus will probably
save a higher percentage of fine gold
and platinum 1t therefore seems that
more efficient methods may yield some
increase in the quantity of platinum
recovered.
The chief problem is to find new
ground for dredging. There are areas
in northern California and southern
Oregon that seem to be favorable for
successful dredging, but 1t will be diff
icult to find ground as favorable as
that now being dredged Good ground
can be found only through close in
yestigation by those who are most fa
miliar with dredging.
Drift Mining.
Old stream channels that are buried
hundreds of feet beneath the lava on
the western slopes of the Sierra New
ada formed the feeders of the grayels
in the areas along the foothills that
are now being dredged These buried
channels are mined by drifting or tun-
neling under the layas, bringing the
gravels to the surface and recovering
the placer gold. Some of these old
channels carry considerable platinum
aside from the gold and at few
places attempts are being made to
mine them more extensively. Drift
mining on scale approaching that of
dredge mining would doubtless recover
an equivalent quantity of the platin-
um metals,
Origin.
/ fha al fDl a lxv
supposed to be derived from the ser
| pentine that occurs in many areas in
northern California and southern Ore
gon. Wherever platinum seems to
this rock is found. roughness of
the platinum and in some specimens a
black or brownish coating, which is
apparently iron oxide, indicate proX-
Unity to its source, but it has not yet
been traced directly to the serpentine,
although ii is probably derived from
this rock. The large areas of serpen-
tine and related rocks in northwestern
California and southwestern oregon
and the gold and platinum found in
many of the streams that drain them
make this country favorable for pros
pecting not only for the platinum
metals, but for chromite. manganese
and cinnabar
Summary.
The possibility of increasing the
production Of the platinum metals,
then depends on improvements in the
methods of saving now used, on the
extension of these methods to areas
that are known to contain these met
ais but that have not yet been mined
and ON the discovery of new produc-
tive ground in northwestern California
and southwestern Oregon, where the
prospects seem to be good. Streams
that carry insufficient gold and platin-
UNI to pay for mining at the prices
formerly prevailing might now yield a
profit. Streams that drain areas of
serpentine would seem to be particu-
larry favorable for prospecting At no
place are the Platinum metals concen-
trated in large quantities. Being rarer
than gold, they are harder to find than
gold, Iridium is in great demand, and
the fact that it forms 10 to 40 per cent
of the platinum metals in nearly all
the placer deposits in the United
States is a special incentive to the
search for more of them. The risk
that must be taken to find and devel-
OPP new sources of supply is great, but
the pressing need would seem to JUS
tify it,
The elimination of litigation and the
equitable settlement of questions re-
garding surface rights and under
ground rights in drift mining and re-
garding the distribution of water for
irrigation, power plants, and mining
might also increase the output. The
present price of the platinum metals,
which is higher than that of gold, does
it's share in encouraging production.
Known Attitude,