The Neihart herald. [volume] (Neihart, Mont.) 1890-1901, 1895-10-26

where the returns of bullion, obtain
ed IN the past are usually available,
it is not impossible to confirm the
of tons said to have been
crushed in order TO obtain that
amount by measurements of the
slopes, levels and shafts from which
the ore was abstracted, and so OBJ
tanned the average yield per ton up
on which it would be fair to base an
estimate for the future. If these re-
turns are available and can be util-
lied for the purpose, it would be
manifestly absurd to neglect or ignore
them; yet we know of an expert un-
der such circumstances ignoring the
past, and the milling returns actually
obtained for several consecutive
years up to the very date of this ex-
animation, and basing his opinion to
large extent, upon a sample of a
hundred weight or so of the ore OBJ
tanned during a hurried examination
with a curious result that his samp-
lie showed that there was no gold in
the ore being treated, the actual
milling returns for the same time
yielding considerably over half an
ounce in gold to the ton.
In every we'll managed mine the
process of sampling is practically a
continuous one, for in order to arrive
at the difference between the amount
of gold actually contained in the ore
and that extracted from it by mill
ing operations, in order to ascertain
the amount of loss, a careful and
systematic sampling of the crushed
ore, and also of tailings, is a part
Of the routine Of the days work.
When dealing with the sampling
of the ores and tailings, as a general
rule it is found that the gold ex-
tracted, added to that left in tail
ings, approximates pretty closely
to the assay of the ore before enter
ing the batteries; in fact as we un-
derstand it, there is rarely differ
ence Of 5 per cent. between the two.
1t is very evident that it requires
a acareful and long continued process
to arrive at the average value of ore
and it is practically impossible for
the cleverest expert to obtain even
approximate results by any other
than a carefully conducted process
while to expect to do SO by knock.
ing of IA piece here and there is a
farce, and is as likely to yield as
valuable an idea of the mine as the
dipping of ones hand into lucky
bay at bazaar.
Enough has been said TO prove
that, wherever possible, bulk samples
only should be dealt with, and car
alone give fairly acurate results. i
will however, sometimes happen
that there are no means of handling
the quantity necessary to arrive a
approximate results by simple
means, such as sampling an ore heaI
and assaying our sample, but it nee
essitates the cutting of trencl
straight through the ore heap, th'
reduction by hand to the size of wal
nut, or under, and the quartering o
the large sample so obtained. The
reduced sample must now be crushed
down still finer, well mixed ant
quartered down again until tn
amount is reduced to few pounds
this may be still further reduced, bu
great precaution must be takeh t.
prevent its being tampered with
as the insertion OF few grains o
gold by any of the we'll know
lodges would vitiate the results.
The sampling of a mine itself is
long process, and will entail til
cutting across Of the face Of the lod
at regular and frequent intervals, tn
careful collection of the mineral s
obtained, and the reduction of il
bulk afterwards by the same syster
, of crushing and quartering down a
before. IF the ore occurs in rec
. shoots, then the samples from ther
should be kept separate from thos
of the poor ones, so that the exter
, and value Of each may be knowl
| Some experts say in their report
I that "after picking out all pieces {
visible gold the sample assayed,
, etc, but if the sample has been fairl
3 taken it seems just as absurd to ,
4 to pick out the gold because it
Y visible, as it would be to take o,
: the sterile pieces of quartz. In bot