The weekly miner. [volume] (Butte, Mont.) 1878-1881, 1881-01-04
SILVER BOW MILL.

AiiC ouoo VI AAaih Soicct, DuJIe anu mas Deen
in continuous operation ever since. The
company is composed of John Downs. Rich
ard s. Jones, Dennis Leary, James A. Tai
bot all practical men who own among
other valuable mining properties in the camp
the Grey Rock, La Plata, Pacific, Flag and
Mount Moriah, which have been developed
with considerable energy during the past
year and each of which has made a good re-
cord in the matter Of ore production.
For the year ending Nov. 80, the latest
date on which we could obtain statistics for
publication, the amount of ore worked in the
mill was 1877 tons. OF this amount, 1,15O
tons was custom ORE, leaving 6,667 tons as
the amount worked from the company's mines.
The total bullion product for the year is $780,
004, of which amount, nine per cent. of the
value was gold. Seventy five per cent. of the
assay value of the ore was saved in the mill
ing process, a very excellent showing when
the base character of some of the ore treated
is taken into consideration. The loss in
treating refractory ores has been so consider
able, however, and such large bodies of base
ore have been opened up in recent develop
ments on several of the company's properties,
that it has been found necessary to provide
roasting facilities. With this end in view,
a Howell 6o-inch cylinder roasting and
chlorodizing furnace similar to that of the AL
gonquin mill, Philipsburg, and to those in the
new Alice mill, has been placed in position
during the past fall and within the last two
weeks has started up on the base ore dump
of the La Plata, a mine which has been closed
down for some time in consequence of the
scarcity of free ore and the fact that the
company had no means of successfully treat
ing base ore. 1t is an easy matter to roast
from 20 to 30 tons per diem and the percent
age of silver extracted is much greater than
before. The Pacific, Grey Rock and other
mines OF the company, however, may be safe
ly depended upon to furnish the mill With
time it is the intention of the company to
treat some custom ore such as requires initial
roasting.
This will be the means of starting into OBJ
Grafton several mines which are now living
idle. There are many rich properties in the
district in which the ore paltakes too much of
a free milling character to render its reduc-
ton by the smelling process profitable, but
which is nevertheless too base formilling pur-
poses without being chlorodized. For the
cheap and successful treatment of this class
of ore, it first requires to be roasted, after
which it may be milled to excellent advant-
age 1t thus appears that a mill with roast
ing facilities, such as the Silver Bow mill now
possesses, will prove ofmaterial benefittowards
aiding in the development of the resources of
the camp.
GREY ROCK.
As an ore producer, the Grey Rock has
achieved an excellent reputation during the
past year. Along in the carly spring months
operations were confined to the east shaft
which is 10 feet deep. The drifts running
from the 40 faot level were actively worked
and many hundred tons of fine free milling
ore were extracted. After the surface bodies
had been worked out to some eA ent, the
sinking of the shaft was resumed to a depth
of II feet, from which point a drift running
west on the ledge was started for prospecting
purposes. This drift was prosecuted for a
length of 225 feet and from one end to
the other, the sides, top and bottom, show
nothing but ore. An ore shoot of a demon7
strated length of 225 feet it may be urged, ought
to have been worked, but it should be re-
nembered that at a depth of Y feet the ore
is below the water line and is there
fore too base to allow Of its being worked by
the milling process without initial roasting
and that until within the past few weeks the
the company had no roasting facilities. The
assay value of this immense ore body which
is from eight to fifteen feet wide is not high
but it can be extracted so easily and worked
at such small expense, that there is a strong
probability that the entire shoot will be
treated. There is every reason to suppose
also that at a greater depth, the ore will be
found of increased richness as it is an almost
invariable rule in Butte mines that the ore
near the water line is of less assay value
than that above or below it.
At a distance of 800 feet west of the cast
shaft, on what is supposed to be the same
ledge, is another shaft sunk to a depth of 92
feet. Forty feet from the surface drifts were
run east and west and such was the size and
quality of the ore body that after considerable
stopping, sinking was resumed until water was
encountered, the object being to thoroughly
prospect the ledge. At a depth Of 90 feet a
crosscut was run south for distance of about
fifteen feet when the ledge was struck. In
stead of being eight feet wide, however, as it
was at the 40 foot level, it had enlarged to %
feet between the walls, the ore being all of
paying quality. Energetic extraction at once
began. Drifts were started east and west on