Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1910-09-03

bearing body presents many features
of a banded vein.
The vein or pegmatite has granite
walls then, on either side, string
er of quartz, the same of feldspar;
then, on either side, the rich pegma-
tite which carries enough pegma-
tite to pay to work. The center of
the deposit consists of the leaner peg
MATTE. The deposit is lenticular in
shape. varying from 3 to 60 #. in
width. 1t has an east-west strike,
and is developed by a tunnel. The
company is at present negotiating
for steam hoist and air compress
ing plant, and it is hoped to start
work on this installation within 80
days. The company sells its product
to manufacturers of electrical sup
plies.
Numerous other properties are
known to carry mica in paying guam
titles, and no doubt many of the pros
poets known today will eventually
develop into important mines. 1t is
confidently expected that a sorting
and trimming plant will be erected
at Custer in the near future. This
would be consummation that
would mean much to the miners Of
that section, as it would afford them
a market for small shipments, and
would without doubt be a PROPOSE
tion which could be made a COM
mercial success, in view of the large
number Of small mines from which
an immediate supply could be drawn.
Mica mined in the Custer district
is as good as is produced in the
world for electrical purposes and as
the manufacturers of electrical ma
chinery and accessories are the larg-
est buyers of mica, it would seem
that the mines Of this section are
destined to be drawn upon for a
large, If not the entire amount equal
to the supply now obtained from
India and Canada.
The prime test of mica for electri-
cal purposes is it's ability to stand
high voltages without fusing. Ex-
haustive tests on the South Dakota
product place the resistance at co.
600 to $4,000 volts-some tests
have shown as high as 100000 volts
This equals the best India and Can
ada tests and far exceeds the North
Carolina product.
Every incandescent lamp socket
contains mica. Practically every
generator and motor contains mica.
Many cables contain mica and we are
all familiar with the fuses which are
covered with a sheet OF mica the
size of 25c piece. Many brands
of prepared roofing paper contain
mica; mica is used to a great ex-
tent in axle greases; fancy sparkling
wall paper and postcards; in fact, it
is used in scores of ways that were
unknown when it first introduced it.
self to the layman as "isinglass' IN
the old fashioned wood stove and
base burner. In fat. the demand
for stove use and the manufacture
of chimneys for gas burners has be-
come second in Importance to .he de-
mand in the electrical he.d.
Millions of washers are annually
made for use in sockets and similar
electrical contrivancas, this demand
taking care of a large amount OF 1
by Lin, by Pin. and 2 by 2-in. sheets
The larger sheets are used in the
manufacture of "micanite" or pre-
pared micaboard of dimensions, Of
II by IS in, and larger. Micanite
is made Of layers of small sheets
and shellac the whole, after being
built up to the required thickness,
being subjected to intense pressure
in hydraulic presses.
The large sheets find ready market
with stove manufacturers and bring
the highest prices, the smaller sheets
are in larger demand with the cleo
trical people, and are worth a little
less money, while the scrap mica is,
in the Black Hills, at least, little
more than by-product, and brings
a trifle more than enough to trans
port it to market.
An indication of the undoubted
permanence of the industry in this
district is the announcement that
the Westinghouse Co. will erect a
large electric generating station on
the railroad at Custer, from which
point power for all of its mines will
be transmitted. The company also
proposes to furnish light for the town
of Custer