Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-04-15

mines were first worked around
/ Lewistown and all over Montana
and the west in general. Higher
efficiency. greater recovery is the
aim of our days.
Now let us look into some of
/ the mineral deposits around Lewis
town, in a general way. First go
to the Judith mountains, northeast
of Lewistown In 1888, several
/ developments were started and
much knowledge obtained from new
ore discoveries. new metal-bearing
minerals as well as economical pos
sibilities of these ores, through
metullurgical Investigations, mostly
carried on by the writer. In the
Judith mountains mineral belt
there are two major groups of
commercial ores. The sulphide
ores are the largest of the two
groups and have many and varied
minerals of economic value The
oxide ores are mostly low grade
gold ores. They are found in large
bodies and are blanket veins
around New Year, Gilt Edge and
Whiskey Gulch districts. They
could be treated directly by cyan
ide. using fine grinding. giving a
greater recovery and cheaper mil
ling operations.
Some of these oxidized ores are
treated by the old process of per-
collation.. However. this system is
antiquated and not always very
efficient. besides wasting much
water or requiring labor to handle
waste material Few of these ores
are workable by the percolation
system. Often part of deposit
is suitable for the process but
most of the ore is usually insult
able and requires fine grinding
and agitation and is treated then
by the modern process of counter
current decantation.
There is in places some silver
chloride but not usually in quantity
sufficient to be of economic value.
other than shipping to smelter. if
rich enough. This type of ore is
usually found in the Outcrops OF
the veins of silver-gold ores. a.
round Maiden and Cone Butte dis
tricts.
The sulphide ores are widely
and various in types
and values They have been CLASH
field by the writer under few
general types, according to their
l. Iron pyrites, carrying gold
and silver
2 Complex pyrite ore carrying
Dold, silver, arsenico-sulphide, tel |
Iurium and anthony sulphides.
3. Base sulphide ores. carrying |
Told' silver copper, lead and some
zinc.
The first type of ores are not
very considerable in tonnage. That
IS. pure gold sulphide ore, most
Of the gold sulphide ores are of the
arsenico-pyrite type. The latter is
round in large tonnage in the
Maiden, Cone Butte and Harmed
district. They are ideal ores for
Ilotation milling process but re-
luire fine grinding. particularly
the Harmed ores, as they are found
in quartzite and schists and the
metallic crystals are finely dis
'eminated thru the gangue rock
Microscopic examinations reveal
close associations of the metallic
minerals with the non-metallic min
erals, chiefly silica, of a very fine
tyne.
In the Maiden district the pyrites
are coarse and easy to free from
he gangue mineral. mostly crysta-
line lime and quartz. such as the
new ore. opened in the Gold Hill
mine.
The second type of ore is very
important. Much of the Harmed
district ores come under that type,
complex pyrite ores. arseno-pyrite,
in large quantity. This type of ore
must be treated by the flotation
process. Some of the Harmed ores
carry beside gold and silver also
little copper and lead sulphide.
At places it is quite heavy in lead.
Ihis type of ore also requires fine
grinding.
Under this classification we have
also a large quantity of most val
liable ore which has produced in
The past much high grade ore, and
S now producing high grade and |
VII be one Of the most productive |
FTREPROOF