Santa Fe new Mexican. [volume] (Santa Fe, N.M.) 1898-1951, 1900-09-07
The VALUE OF PLACERS.
A Controversy as to the Best Method Q
Testing It,


A spirited controversy is now in prog
ress between mining engineers of the
country regarding the best method of
testing the value of placer ground. The
| efficiency of the pit, where the gravel
deposit is shallow and there is no wa
ter to interfere with the work, is con-
coded. w. A. Parish always adopts this
method where possible, and says that
it is the only way to insure exact re-
suits, but where the deposits are flat
and considerable underflow exists the
sinking of a pit is always expensive and
frequently impossible, and the practice
has been to use the Keystone drill used
in sinking oil wells. 1t is in regard to
the efficiency of these machines that
the discussion is now progressing. The
Gold Pan company, Of Breckenridge,
several companies in Montana and the
North American Gold Dredging Com
pany, operating the Swan River placers
of Colorado, have all used the Key
stone drill and claimed good results,
but Colonel Locke, of Cincinnati, an
eminent mining engineer, when there
last week, on his way to examine q
placer, said that it was practically i'm
possible to secure accurate results with
the drill.
II need not say" said he, that the
specific gravity of gold is such as tC
cause it to move with the least dis
turbance Of the surrounding gravel OF
sand. 1t follows, therefore, as a matter
Of course, that the constant churning
of the drill has the effect of concentrat-
ing the gold, which follows the drill
downward, and the result is that the
sand pump does not bring up the gold
which existed in any particular portion
of the hole prior to the Introduction OF
| tha ,1rsl1 on1 thot union ho1roal ic
reached there is a phenomenally rich
gold deposit, which was not there be-
fore the ground above was disturbed
Now the object of an examination Is
not only to discover the gross amount
Of gold contained between the surface
and bedrock, but to obtain the average
value per cubic yard, and we want tc
know what each vertical foot or yard
of the hole contains. This cannot be
done if the constant churning of the
drill drives the gold below, and there Is
no sense in an engineer deceiving him
self. The sinking of holes is the most
economical method of testing the value
of placer ground, and with the most
careful operation there is certain to be
more or less disturbance and n
quent concentration. The aim of the
engineer should, therefore, be to make
as little disturbance as possible, and ]
am strongly III IdVOr OF using d PIP III
ground where there is a considerable
flow of water, driving a 16-inch pipe to
bedrock and pumping out the sand as
J the pipe is driven downward. Where
the deposit is deep and the water is en-
countered at some distance from the
surface. the best results are obtained
by sinking a pit to the water level and
then driving the pipe down to bedrock
through the sand and water. In that
way an approximately accurate record
can be obtained of every foot of the
ground penetrated When a boulder is
encountered that is too large to pass
through the pipe the incumbent sand
and gravel should be carefully pumped
out and the boulder broken by a drill
into pieces small enough to be taken
up by the sand pump, and when bed
rock is reached the shoe of the pipe
should be driven several inches into
the rock, so as to form a tight Joint that
will prevent the inflow of sand and'W a
ter. Then the rock within the pipe may
be broken up with a drill and the hole
pumped dry. BY this method a reason
ably correct record may be obtained Of
the contents of each yard of ground"