Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1941-07-26

The lower end of the sluice boxes
had iron rifles which caught the sap
phires as they sank to the bottom due
to their high specific gravity. The
sediment and ore from the sluice boxes
was held back by dams, the contents
of which were cleaned out every year
and examined for sapphireS, the
coarser tailings being left fer further
weathering.
The water was turned out Of the
sluice boxes, the rifles lifted out and
the sapphires taken from them. In
the early days of sapphire mining, the
soft sediment taken out with the sap
phireS was PANIED as gold Is, but later
magnetic separator was Installed 70
separate the sapphtres from the other
ore.
Washing operations were limited to
the months from May to November.
The larger sized concentrates were
usually hand sorted at the mine, but
the gem stones were sent elsewhere,
first to London, then to Amsterdam,
France and Switzerland, for grading
and cutting.
MIL Built in 1906
At the American mine, ore was
worked In much the same manner as
at the English mine. The mill, built
in 1906, was erected against the hill
with a ground floor and second story
floor. The third step or upper section
was on level with the tunnel into the
side Of the hill.
A 1OO-horsepower steam boiler, al
75-horsepower Corliss engine and a
direct connected dynamo were in
stalled to supply power for the mine
as well as the mill. The ore was
brought from the mine to the mill by
an elestric hoist in mine cars and
dumped in the disintegrating screens
which revolved in water-tight tanks.
The revolving screens had buckets
on the outside. AS the screen revolved,
these buckets picked up the fine sedi-
ment and sapphires and dumped them
into a sluice box which emptied into
an elevator. From the elevator it went
to sizing screen which sized the ma
terial then finally to two Woodbury.
jigs. one classifier and the other a
safety Jig.
Use Jig System
A jig is a system Of beating water
through screen bottomed boxes. The /
classifier Jig separated the slum from
the other material, while the safety jig /
saved what might have gone on over /
the classifier. The coarse material from /
the shaking screen went to bigger |
Jig made to handle coarse gravel and !
other screened material from the ore.
The oversize material from the shak
ing screen was taken outdoors, put on
, dump, left to disintegrate for year
and then taken back to go through
he same process Of revolving, shaking
md jigging.
Water was piped into the mill from
Togo creek to be used In the processes
If washing and screening. The material
Iaved was the concentrate which con-
aimed nearly as much iron as sap
1hireS because the two have about the
anne specific gravity.
The eoarser concentrate was hand
Kicked for sapphireS, and the finer run
,ver rollers charged with electricity
which caused the iron TO be repealed
rom the rollers, while the sapphiFes
lid ON over and dropped into contain
as with dividers below.
cruSher Classes Less
One Of the innovations the American
company undertook TO introduce was
! crIsher to break the hard humps (
4 ore instead OF waiting for them to
% dissolved by the elements, but 1t
lad to be abandoned as it crushed the !
anger sappnires.
The ore deposit fills q vertical fis- !
rre forming q dyke similar 10 the {
diamond bearing clay OF South Africa, /
bout feet wide, "a miles long, and I
{ unknown depth. This, with the pos (
fhle exception Of the South African
iarnond fields, Is the largest deposit
{ gem bearing ore 10 the world.
The origin Uf the sappaaireg Is be-