Santa Fe new Mexican. [volume] (Santa Fe, N.M.) 1898-1951, 1900-12-18
THE VALUE or MICA.
Its Treatment and the Uses to Which II
Is Put,

The value of mica to the electrical "a
dustry cannot be over-estimated. Iii this
respect it may be said to rival copper,
with this difference, however, that
whereas aluminium may be substituted
for copper in very many cases, there is
nothing that can be made to TAX the
place of mica as an insulator in cleg-
is due to its excellent insulating quail
ties and to it's elasticity.
Mica is an a%nhydrous silicate of cal
cium and aluminium, and crystalllZetl IN
a Illuminated mass, easily split along It's
axis, and can be subdivided down to
three ten-thousandths of an inch in
thickness. Deposits of this mineral are
found in various localities on this con
tinent, but the occurrences of pockets
in which mica is found cannot be pre-
dicted by the geological formation,
which makes this form of mining one
Of the most hazardous from a financial
standpoint.
1t is from India that the best quality
of mica is obtained, and it is the mines
of that country that have furnished the
bulk of the worlds supply for centli-
ries. These mines, the principal one of
which goes by the name of "Abruker,'
are situated in the interior of the
try, remote from civilization ami ~
tremely inaccessible. The deposits are
worked to-day as they were when Gaze
sar ruled over Rome, in a most prini-
tive way. The Abruker mine has been
sunk about 200 feet, following the pitch
of the vein, and all the mica and refuse
are carried away by the natives. No
machinery of any kind is used, except
mica are placed in baskets, which hold
about 10 pounds, and are passed up
from hand to hand by women who
stand in line on a ladder. When the
and returned down the ladder in the
same manner, but by another line of
women.
After the crude mica is taken from
the mines it is first roughly trim!nca
and then sorted into different grades,
according to sizes and quality. II is
her taken to mica workers, who spit
it up and mark out the size for it to be
cut into by the shearers. The cut tiHcea
are her cleaned, weighed and packed,
ready for shipment. After the proIuct
has been made into packages it is load
ed into carts, drawn by bullock!', and
carried in this way hundreds of miles
to shipping points at a speed of about
ten miles a day.
AS already stated, the fact that mira
is elastic, f%reproof, and it's Insulating
qualities unaffected by time, has mad"
it peculiarly adapted for use in con
struction of electrical machinery. 1t
has been used for vibrating plaje s in
the photophone, and Edison at n time
employed it for telephone diaphragms.
In commutator work mica is indisnen-
sable, as well as in electrical measur-
ing instruments, and hundreds of other
electrical applications. For the purpose
of armature installations in high tension
alternating machines mica is especially
adapted, but unfortunately the expense
of the mineral has to a great extent
prohibited its use, in spite of the fact
that the insulation of mica in megohms
per inch is expressed 33x10(6) at 20 de-
grees Centigrade.
AS may readily be inferred, the de-
mand for mica in the United States far
exceeds thai of any other country.
From 1868 to about 1877 deposits in
North Carolina furnished the bulk of
the mica made use of in this country.
AT the latter date the supply in the
south began to fail, while the demand
for this commodity was on the increase,
due to the rapid growth of the electrical
industry. This made it necessary to i'm
port the article from India, with the
result that where formerly Great Brit
ain was the principal user of Indian
mica, the United States of recent years
has taken about double the quantity
sent to England.
Various uses are made of mica waste,
Among other things insulators are pro.
duced by splicing up the mica into lam
mae and reassembling these thin sheets
and solidifying them at a high temper
allure and under a heavy pressure. The
improvement effected by this treatment
is claimed to be increased insulating
properties over ordinary mica. How.
ever this may be, there would seem lit
tie doubt but what the patented prod
uct just referred to, as well as several
other substitutes for mica, have proven
a valuable adjunct to glass, mica and
other insulators made use of by the
electrical industry.
A coon THTNG