Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1907-09-07
PRODUCTION OF MICA In 1905.

Or the minerals composing the grouI
called mica practically but two-musco
vite or potash mica, phlopapite or mag,
nesia mica--are industrially important
and only one of these, the muscovite il
found in deposits of commercial value
in the United States, says the Chicago
Mining World. Muscovite is widely
disseminated in small plates and cry.
stalls, OF no value, in crystalline igneous
and metamorphic rock, as well as in the
sediments derived from them, but the
commercially valuable deposits are con-
fined to pegmatte-a rock closely allied
to granite in composition, composed of
feldspar and quartz with more or less
mica and other minerals, but unlike
granite in that its minerals are crystal
lized ont in large masses. Among the
coarser products of this crystallization
is the mica, blocks of which more than a
yard in diameter have been found.
The properties which give mica its
value to the world of industry are it's
perfect cleavage, the toughness, flexi-
biIity and elasticity ofits cleavage sheets,
and its transparency and nonconduc-
tivity Of electricity The three princi-
pal uses of the material are for electrical
insulation, glazing and decoration. The
first named use probably leads in pres.
ent importance, but the other two uses
date back to ancient times, mica ante
dating glass and also being early used
TO secure decorative effects. As an in
sulating material it occupies place that
can not be filled by any other known
substance. Recently the utilization of
scrap and waste mica in the manufacture
of lubricants for car axles has become a
somewhat important industry in the
west.
The increasing use Of the material has
largely modified the demand made up
on the mining industry, for not only can
sheet mica of small size now be utilized,
but even more important is the extern
sive use that is now made of composite
mica, nodded mica, "micanite," and
other varieties of built up sheets. Scrap
mica is also utilized in the manufacture
Of superior quality Of boiler tagging,
and ground mica is used in somewhat
increased quantities in mica bronzes and
paints and rs an absorbent for explo.
sives. The finest ground mica, or mica
flour, finds considerable market with
manufacturers of high grade wall papers,
the luster obtained by the use of mus.
covite dust having the advantage of both
permanency and brilliancy.
In an advance chapter from the min
eral Resources of the United States, Cal
endar Year 1906" Douglas B. Sterrett, Of
the United States Geological Survey, re.
ports the production of sheet mica in the
United States for 1906 as l,423, 100 lbs,
valued at $252, PAS, and of scrap mica as
,4S9 short tons, valued at $22,742.
These figures show an increase over
those for 1905 OF 49S, ,225 lbs in quantity
and S9l7,5l6 in value for sheet mica, and
of 1868 tons in quantity and $4,SS6 in val
ue for scrap mica. The eight states
which shared this production are, in or
der of value of output, North Carolina,
Colorado, New Hampshire, Virginia,
Idaho, South Dakota, New Mexico and
Connecticut
The imports of mica into the United
States in 1905 were the largest ever re-
corded, the value being considerably
more than twice as great as in 1902 and
aud 1905, the years that formerly held
the record. The total quantity import
ed and entered for consumption in 1906
amounted to S,O66, 73S lbs, valued at ST.
042,6OS.
The total production and consumption
of sheet mica in the United States in
1906 was 4,4S9 S3S lbs, as against 2,5l9,.
AS lbs. in 1905, an increase of about 7S
per cent. A comparison of the import
figures with those of the home produc-
tion shows that there is wide field for
the extension of the industry in the
United States, and indeed the industry
is expanding rapidly to meet the de-
mand. Deposits carrying mica in com
mercial size are found in many parts of
the United States from the Atlantic coast
to the Pacific, and new developments are
reported each year. Alabama and Geor
gia will probably appear in the list of
producing states in 1907, and other states
will doubtless show large gains in pro-
duction.