Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1894-01-13

The mill tests were made under m
personal supervision with great care
the amalgamations Of the ores i'm tn
battery was done by Mr.. A. l. Read
chief amalgamator of the Deadwood
Terra mill; the concentration of the sui
phurets was carried out by Mr.. Jane
ilarIgering. skilled millwright, ant
the sampiiDg of the ores, assayiug ans
melting by Mr. Frank Tindall, in cbarg
OF that department at the school o
mines. Each lot of ore was run by IL
self. the mill being thoroughly cleanet
after each run.
l have to report that in making thes'
mill tests, the machinery worked well
that all the free gold from the ores wal
saved In the battery repeated tests o
the tailIngs by panning tailed to show {
color OF gold. The sulphurets were O.
completely extracted from the failing,
by the Frue yanner, that the tails from
that concentration assayed only thirty 70
eighty cents per ton, and on banning
| gave but trace Of sulphurets
The results obtained by milling, saving
The exception hereafter noted, agreed
very closely with the sampling and as
saving. BY subtracting from the gold
contained in the ore by fire ASSAY that
contained in the tailings, the remainder
closely Appropriated the yield Of free
gold added to the value of that in the
concentrates
The stamp battery was provided with
inside amalgamated copper plates, in adj
dition to the amalgamafed plate on the
front table The ore was crushed
through No. punched screen, equiva-
lent nearly to 40 mesh wire screen. In
cleaning up the battery after making
runs of samples numbered respectively
one, three and four, all the gold obtain
ed was from the amalgam scraped from
the inside plates, front table, nd from
the small quantity of quicksilver caught
an the traps" and extracted from the
battery sands panning. In the lots of
ore above mentioned. from different
openings on the NorthlStar and Frei
berg lodes, not particle of coarse gold
was found in the battery sand. although
all the material retained in the battery
was panned.
In cleaning up the mill after making
the run on sample No. 2, consisting Of
two tons Of quartz from the Gold Hill
mine, there was found in the battery
sand taken from between the dies.
quantity Of coarse gold and large num-
Der OF gold nuggets. varying in size from
particles the size Of pin head up TO
that OF a pea. together with several mug
gets from one-fourth of an inch to over
one inch in length. These nuggets when
taken from the battery were thinly coat.
ed on the surface with quicksilver and
were apparently not altered materially
IN shape, the sharp edges and thin parts
OF the nuggets not having absorbed suf-
hcient quicksilver to soften them. The
nuggets thus obtained were not mixed
with the amalgam scraped from the
plates but were kept separate and treat.
ed az follows: They were gently heated
in muftie furnace to a low red heat
sufficient to sublime all of the quick
silver coating, but at heat far below
the melting point OF gold. After thus
removing the quicksilver the nuggets
acid for few minutes, then weigheYs
and placed in bottle for further invesh-
CATION. The amalgam obtained in this
run from the plates was treated in the
usual manner and on calculating the
result of this mill test the free gold was
found to be but slightly greater in guam
tity than should have been obtained ac-
cording TO the results of the fire assays
on the samples of the ore taken az ii was
crushed and fed to the battery, This
lot of ore from the Gold Hill mine,
some three tons l had exam
ined at the time of its arrival / subse-
quently had examined the quartz more
thoroughly a. it was broken and passed
the rock breaker, and not hav-
ing detected by such inspection the
slightest color of free gold in the ore,
could but regard this occurrence Of so
large a quantity of coarse gold, together
with nuggets Of such unusual size for the
ores Of this region, as being, to say the
least, abnormal. Further. there had
been taken by Tyndall before this lot
of ore had been put through the rock
breaker, large average sample Of some
thirty pounds, by cobbing the fragments
of quartz with a hand hammer: this
sample of quartz was crushed. quartered
down. and an average lot of two pounds
crushed fine until all he sample passed
through an S0-mesh sieve. Neither
scales nor particles Of gold were found
separate or caught in the meshes of the
sieve and on panning an average sample
obtained small quantity Of minute
COtOTS Vi kolu Out uo COtTcc ROlu Wiidt-
ever. AS precaution, a second and
larger sample had been taken Of this
Gold Hill ore, by reserving one half
shovelful Of quartz from each bucketful
(of 65 pound weight in feeding the bat
terry. This latter sample weighing over
200 pounds, was coarsely crushed and
quartered in the usual manner; on test
ing by panning and by passing two
pounds Of average pulp through q fine
sieve. not any coarse gold was found.
BY fire assays made in triplicate with
unusual care, the following results were
obtained:
Result Of fire assays made on average
samples Of lot of 900 pounds Of
quartz from the Gold Hill mine near
Custer City, South Dakota.
No. l. Sample taken by cobbing--
Value of gold per 1000 pounds. 1891.
No. 2. Sample taken from battery
feed-Value of gold per 1000 pounds,
SO 20.
The yield in the mill test on this lot
Of ore was as follows:
Value Of free gold from plates per ton
of 200 pounds. ACKNOWLEDGEMENTS. o. 63
Value OF free gold In concentrates per
ton Of 2,Oo0 pounds s............... ~
Value of gold In tailings por ton Of
90 IS
As the fire assay gave 1891 per ton,
the result Of this mill test. excluding the
coarse gold and nuggets found in the
battery, exceeded the fire assay by forty
seven cents per ton. An evidence that
the coarse gold in the battery had hut
little affected the Weld in gold contained
in the ore and caught upon the plates.
At a subsequent date in order TO rend-
er still more certain the true grade OF
this shipment Of ore; the following mill
run was made by the school on its own
behalfand expense without the presence
or knowledge of any interested party,
working the remainder Of the original
lot of some three tons of ore that had
been left over after the first run Of ZOO
pounds had been run through the mill.
Result Of a mill run on quartz from
the Gold Hill mine. made at the expense
| of the school of mines:
Weight OF ore crushed ed............ 4 800 pounds
\ Fire assay OF average sample taken from
battery feed per ton. ...........,.... SS 10
Return per ton Of 1000 pounds;
| Free gold from battery amalgamation. 81 u
Gold contained In concentrates. ........ ~
Gold contained in yailings.. .............
| Total. =. sa sI
The above ref,ulta agree In ASSAY value