Tonopah bonanza. [volume] (Butler City [i.e. Butler], Nev.) 1901-1909, 1904-09-03

1890 80 t~bASN W. hAl1 tAAAA
to start on; but an examination of
this caused the writer Owing to the
waste and ''bull quartz" mixed with
i) to call the bender to one side and
tell him that before the test was
started he must remember that a
"custom mill sometimes cheats" No
further explanation would be given,
but a a result three samples"
were brought for assay to serve as a
guide to the large values in the ore.
One piece, four ounce in weight,
represented an average sample of
the ore sorted out for shipping, and
supposed to be worth $500 or more;
the second was one piece of the null.
ing ore, clean quartz and one pound
in weight; while the third consisted
of three pieces of clean quartz, each
the size of a walnut, which constituted
the average sample of the twenty
tons sent to the mill. The shipping
ore assayed $40 per ton instead of
$500 as in the ore Of the company's
mine identical in looks; No. 2 gave
So and No. 3 So. The test was made,
amalgam saved, retorted and as
sayed, concentrates dried, weighed
and assayed, and the tailings during
all the run Systematically sampled
and assayed, and the total value of
the original ore, combined from these
several items, gave only So 80 per
ton. Then the bender wanted to
know what became OF the values, as
the average OF the three samples was
So per ton, and if the writer had not
shown him while on the ground the
true facts If the case-a minute
quantity Of clean quartz assayed and
a working test Of a large quantity
taken out Of the mine just as blasted
and carrying waste and barren
quartz-he would never have been
persuaded but that the mill owners
had absorbed for their own benefit
the difference Of "a 80 per ton. This
is by no means an extreme case, and
though this gentleman was a shrewd
and successful business man he knew
nothing about sampling, and all rocks
looked alike to him.
In general a man has not the
proper facilities IN regard to floor
room, crushing devices, storage bins
and other adJuncts to allow the oper-
ationS Of systematic sampling such as
is employed by a smelter or a custom
sampiing works, but even with linn
tied ground, a really accurate sample
can be procured by exercising care
and judgment.
Before entering into the various
ways this can be done, it will be well,
even though accused of explaining
something every mining mar knows,
to describe briefly the regular custom
sampling,
The ore is emptied from the sacks
ON the pinnacle Of a cone, or, if Of
several tons, on the edge of an ex-
tended wedge, and the large pieces
are broken with a hammer to a
nearly equal size, not to exceed two
: inches in diameter. When all the ore
; Of this shipment is emptied, and the
sides dressed to a uniform slope, the
sampling is begun. Depending on
the intrinsic value of the lot, from
nine to two shovels OF the material
are thrown on the shipping pile one
: shovelful on a cone, so that, with the
samplers starting from each end,
there remains after all the ore is
! shoveled, two cones, which contain
: from one. tenth to one. third OF the
! original bulk. This is then put through
> a rock crusher and reduced to a size
not to exceed that OF cherry stones.
' II no crusher is available, it must be
broken to at least one half its orig
; inal size by hand, An iron cross is
/ now laid or the sampling floor and all
|. the material again shoveled alter
nately from each cone, one-half to
the shipping pile and the other half
on the cross. When this is completed
! the men with square pointed shovels
: walk around and around the cone
! gradually lattening it and drawing
: the ore uniformly to the outer cir
: conference till the top Of the iron
cross appears. Then opposite quar-
! tiers are shoveled to the shipping
pile, and the remaining quarters re-
I, coned in the same way till the bulk is
, reduced to about fifty pounds. This
is then put through a fine grinder,
! screened through a sieve of 30 or 100
meshes, and further reduced by quar-
: tering to the assay sample. The
= final work must be done in a room
free from d~raughts and separated
! from the main sampling
In the caSe OF concentrates or pre-
: cipitates no crushing of course is
. needed; but the operation otherwise
\ is the same. Should the material be
| of very high grade it is advisable,
aftor tho 6r.t nopaipn IN sapo, 30 70