The Ketchum keystone. [volume] (Ketchum, Idaho) 1885-1899, 1890-06-07
pRospEcroRs' MAPS.
They Will Tell Where Gold May
be Found.

1AOSo in cnarge Oh LHe geOlOglcal
, survey Washington are preparing
maps on large scale, showing the
exact spots in California and else.
where in this country that give
promise of producing gold. These
are intended for the use by pros.
pectors, who have heretofore worked
at random.
It is generally supposed that gold
is only found in stray places and
isolated localities, whereas the fact
is that it is the most widely distrib-
uted of all metals. Every gravel
bank and sandbar is a mine Of it,
the only trouble being that there is
not enough of the metal present to
pay for the process of separating it.
There is not a carload Of sand on
the Pacific slope that will not yield
at least Color" says report re-
Gently issued, and Los Angeles is
built on soil that would very near
ly pay for the panning just for the
gold in it. The yellow mineral is
everywhere almost, and why?
Simply because all of it found in
the world was originally deposited
by sea water during those ages when
the waves Of oceans overhowed the
continents. Under certain chemi-
cal conditions sea water will dis
solve gold and hold it in solution,
and thus it happened that during
the epoch referred to the ocean was
tincture of this metal. Gold was
one of the elements entering into
the original composition of the
forming earth crust, and the sea
water held it suspended for time
and finally deposited it, as if with
the intention of putting coat of
gliding on the globe. But in some
places conditions were more favor
able than in others for the reception
of the deposit. For instance, the
California hills in the process of
formation were, by causes geologic
al, all crumpled up, SO that cracks
were left everywhere to be filled up
with whatever the sea water had to
precipitate. In these cracks and
assures, in the course of centuries,
gold collected with other minerals
deposited in the same way, and in
this manner were formed what are
called gold bearing veins. Such Of
the gold thus concentrated as was
washed down by rivers end torrents
that ate away the hills was found
loose in the soil or in the beds of
the streams, while what remains in
the rocks must be got out by min
i G and crushing.
1t is believed by geologists that
all the gold in the earth is on the
surface of the globe, or very near
it, it being found that the supply
dwindles to nothing after mining
operations have reached a very
moderate depth. Quite otherwise
is lit with silver, which was all thrown
up originally from the easth's bow
els by volcanic action. Just as
occurred in the case of the gold,
the floods of ocean took up the sill
yer and deposited it wherever cir
cumstances were favorable, as in
Nevada, where one silver-bearing
crack in the rocks at Virginia City
has already been mined to the depth
of 2,2OO feet without getting any
where near the bottom. This is the
largest body Of silver ore ever dis
covered, with the exception of one
in Peru. Mining at this great depth
is carried on with the utmost diff
Guilty, owing to the heat.
The processes employed by the
geological survey in the examina-
ton of rocks are most interesting.
To begin with, chip of the stone
to be investigated is ground down
on one side with an emery-wheel
until it is an absolute plane, per-
fectly polished. The polished side
is then attached to a piece of glass
and the other side of the stone chip
is applied to the emery-wheel until
the chip itself is ground all away,
save only a film Of inconceivable
thinness that remains stuck upon
the glass. This film is finally re-
moved with great care and placed
upon little glass "slide" of the
sort used for objects to be inspected
in the microscope. Another piece
of glass, very thin, is placed over it,
the two glasses being stuck together
securely, and now the stone is ready
to be examined.
For this purpose it is put under
a powerful microscope, in which an
is provided for polar
izing light. Looked at through the
instrument in the ordinary way,
stone, which resembles a mere blot
of discoloration on the glass to the
naked eye, is exhibited merely mag
nifed enormously. But when by
the turn of a screw the light polar
lied, the object is suddenly dressed
in the most gorgeous colors of the
rainbow, each element found in the
rock taking on hue of its own
brilliant blue, red, green or what
not. Thus the study of the stone
and its constitution is rendered