Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1903-05-16
THE CROWN MICA MIME

THE CROWN MICA MINE
Is Proving Upon Development to be q
Bonansa. and pne of the Solid
Institutions OF Custer.
On Monday last I rode out with the
Supt. in charge, Mr.. Denis Henault, and
was permitted to.examins this group of
mines to my full satisfaction, and as q
faithful scribe I will ntW endeavor to
give the result to the readers Of the
CHRONICLE.
The Crown mica mines are situated
about three miles in q northwesterly di-
rection from Custer City, Custer county,
South Dakota, on the eastern border of
q large and beautiful park, where at an
elevation Of about 6O00 feet above sea
level, It presents the appearance ofa vast
rounded dome, from the central apex of
which the white mica bearing material
crops out in bold relief. The property
consists Of two claims each 800 by 1900
and one claim Go by 1900 feet amount
ing in the aggregate to about 40 acres OF
mica bearing mineral ground. The inn
provements which have thus far been
put upon the property consists OF a fully
equipped plant for the mining and sort
ing of mica, with shaft house, black
smith shop, engine room, boarding
house, office, change room, mica house,
stable and sheds. All OF which are
commodious and comfortable, and we'll
calculated for the purpose for which they
were erected.
DEVELOPMENT
consists of first, large open cut which
has been run near the top Of the bill,
commencing on the south side and run
ming northerly for distance of 400 feet,
where at the face it has attained the
depth of about 35 feet. This cut which
has been worked from time to time since
the first discovery of the mine, has yield
ed an excellent quality of mica through
out it's whole length, breadth and depth.
This cut has served its purpose and
should now be abandoned. 1t has yield
ed thousands of tons of mica, and by cut
ting through the top Of many pay shoots
il has disclosed the vast possibilities of
production, and has given assurance Of
the great wealth of mica which the mine
contains. 1t was however, but q make
shift method Of mining, which should
never have been done, as it disfgures
the ground, Is q source of danger, and
the mica can be much more profitably
mined from drifts and slopes at the vari-
Gus levels. The main shaft is a two
compartment has reached depth of 100
feet, and from which drifts have
been run TO the extent Of 200 feet. From
the 50 foot level drift has been run to
the west for a distance of about 40 feet,
and branching from this drift two other
drifts have been run to the north and
northwest, each following a large and
rich shoot Of mica of a very excellent
quality. These shoots vary from six to
II feet in diameter, and are nearly
round. These round shoots or pipes of
mica have walls Of hard micacious slate.
which is here the country rock. 1t
bends around and encloses the matrix
Of coarsely crystalline granite, in which
the mica is found In books of every con-
ceivabe shape, and Of all sizes, from one
inch to sheets Of from 20 by 80 inches of
clear mica. There is another shaft
which has been sunk near the north
end Of the cut which has attained the
depth of 80 feet, and drifts have been
started to the south and west. We un-
derstand that it is the purpose of the
management to extend these drifts in
the near future, to cut the different
veins of mica which are known to exist
on each side. In the further develop.
ment Of the mine these shafts will be
connected at the 100 foot level, which
will insure good ventilation at all times.
They are both we'll situated for the con-
venient working OF the mine.
THE FORMATION.
The country rock in which the veins
of mica occur is known and classified as
the Archaen, or old micacious slate,
which is the oldest and lowest strata Of
the earth's crust. We may therefore
conclude that these veins of mica will
extend to the most profound depths, as
the veins dip with the cleavage of the
states, which descend ipto the earth at
al angle of about 20 degrees from hori-
zontal. The veins Of mica conform to
this dip to the west as they 60 down
but the pipes which are formed like so
many stove pipes, lying one on top of
other, are connected by stem which
divides the roof by a streak of mica
bearing material. This streak is usually
from one to two feet in thickness there
by connecting the whole as one continu-
GUS vein. The veins thus far opened
are five in number, lying side and side
| with their rounded shoots have also
dip to the south of about 80 degrees from
horizontal. Thus one above the other
with singular regularity as to direction,
size, permanence and the uniform guam
tity and quality of the mica contents,
they all descend into the earth. This is
a valuable feature, as it goes to show
that these pipes descend to great depths,
and they are so full of books of mica,
that it has the appearance of being full
half of it of that valuable material.
Again we know from the groupings at
the surface as we'll as development with
depth that there are veins beyond veins
of mica, which have not yet been opened
up, and there are pipes below pipes
which have not yet been penetrated.
| EQUIPMENT.
The plant is equipped with a good 35
horse power boiler and engine with
steam hoist, an electric dynamo, with
separate power, sufficient to light the
mine and run the drills, everything
working smoothly, and without hitch.
/ also learn that compressor Of large
capacity was ordered on the 9TH inst. and
will be here soon.
THE CREW.
They have an excellent crew of men,
discreetly selected by Mr.. Henault, who
has long acquaintance with all of our
miners, and many years Of experience
in the mica business.
OUTPUT.