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Talc is one of the most important industrial minerals and is the
most common mineral for daily use as a body and face powder.
Talc, a word derived form the greek word talq meaning pure, is a
The Present Scenario
There are important deposits of talc in Austria, Italy, France, and
Canada and in the United States in California, North Carolina, Texas,
Georgia, and Montana. Talc is used in making paper (as a filler),
paints, face and talcum powder, soap, fireproof roofing, foundry
facings, lubricants, linoleum and oilcloth, electrical insulation, and
is also written as H2
which corresponds to 4.8% H2
O; 31.7% MgO and 63.5% SiO2
It is essentially a secondary mineral formed by the hydrothermal
actions and regional metamorphism of magnesium rich rocks like
dolomite, pyroxenite, amphibolite, seerpentine, dunite and chlorite.
In pulverized form it is whiter in appearance. The compact variety of
talc is called steatite or soapstone. The word soapstone has been
named probably due to its soapy feel. The impure and hard variety is
called potstone, which is mainly utilized for making carvings, models,
decorative vases, utensils, pots and the like and hence the name
French-chalk is the trade name of pulverized talc of pure white
quality which forms the base for many cosmetics and toilet
preparations. Talc is valued for its extreme softness, smoothness,
high lubricating and hiding power and ability to absorb oil and
grease. It is chemically inert to acids and alkalies.
It has been found to be an excellent filler. It can withstand
temperatures upto 1300ºC. It has low electrical and thermal
conductivity. Above all it can be easily powdered, cut and sawn into
any shape and size. These properties in talc are of extreme value for
various industrial applications described later in this chapter.
Talc is found in three forms, fibrous, nonfibrous and massive. The
fibrous variety consists of rich proportions of tremolite,
anthophyllite, and serpentine. The nonfibrous variety contains mostly
of srpentine and carbonates. Fibrous variety is slightly difficult to
||Kerolite Magnesium Talc
||MgO 31.88 %
SiO2 63.37 %
H2O 4.75 %
|Silvery Green Grey white
||Has a soapy feel to the touch
||Dull to pearly or greasy
It occurs usually intimately associated with magnesium-rich minerals.
Anthophyllite, termolite, diopside, dolomite, sometimes quartz and
calcite are the common minerals found in association with talc. It is
found as soft mass in the forms of bands, lenses and vein-like bodies
enclosed in dolomite country rock. Veins vary from small in dimensions
to very large, usually 25-40 metres long and 12-18 metres wide. It has
been mined up to a depth of 20 metres. Lenses of soapstone are
separated by dolomite and also dolomite is found enclosed within the
soapstone mass. It is of compact variety.
Classification and Preparation for the
Talc is classified according to its colour (colour of the powder) and
softness. There is no standard basis of classifying it. The whiter
variety is preferred to dull and other tinted varieties.
Talc is mostly used in pulverized form. About 90% of the world's
production is pulverized for various applications and the remaining
10% is used in the form of bricks and blocks. Suitable lumps are
picked up from the run-of-mine for making into blocks and cut into
different sizes with the help of knives. Other materials are sold to
pulverizers for resale to consumers. Talc is pulverized to varying
fineness, from 200 mesh to 325 mesh. For the preparation of cosmetics,
talc of over 300 mesh is required. The fine mesh sizes of 200 and over
are prepared for use as filler in paper, rubber and textile depending
upon the fineness required by the consumers. Market specifications are
dependent upon the colour, fineness, chemical composition, oil
absorption property and bulk density.
Talc is one of the most important industrial minerals and is the most
common mineral for daily use as a body and face powder. Talcum Powder,
the name derived from the mineral itself, is used in most urban homes
the world over. The invention of perfumed talcum powder has been a
contributing factor in the growth of modern fashions in cosmetics. The
use of talc was known to civilisations in antiquity. The ancient
craftsmen of the Mohenjodaro and Harappa civilisation, (in Sind, now
in Pakistan), about 5000 years ago, exercised their skill on steatite,
engraving their seals with representations of animals and mythological
signs, before subjecting the carving to heat to acquire hard, white
lustrous, enamelled surfaces. Small sculptures, ornate bosses and
vessels were also made from the mineral during those early times.
Pulverized talc has wide industrial applications as filler in rubber,
textile, plastic, linoleum, asbestos products, polishes and soaps; as
a loading agent for paper of all kinds; as a carrier of insecticidal
and pesticidal dusts and for coating calcium ammonium fertiliser. Most
of the rubber manufacturers use talc powder as a lubricant to prevent
ungalvanized rubber goods from sticking. The purer variety of steatite
after calcination, industrially called 'Lava' is used in the
manufacture of low loss ceramic materials required for high frequency
insulations in all kinds of radio, television and related instruments.
Bricks made out of crushed steatite bonded by sodium silicate are used
for ssthe manufacture of furnaces in which argentiferous lead is
softened before desilverising. Paper industry accounts for about 50%
of the total consumption, in the domestic industry, 15% is shared by
the insecticide and pesticide industries and only 3% by talcum powder
manufacturers. The remaining quantity is consumed in textile,
ceramics, paints, rubber, foundry facing and other industries.
Talc both in pulverized and brick forms, are used in this industry.
Pulverized material of 200-300 BSS sieve is required as filler. It is
used in the same way as china clay, that is, the talc powder is mixed
with pulp before making into paper. A number of paper manufacturers
are changing over from the use of china clay to French chalk as filler
and loading material. The brightness in talc is 85 to 88º as
compared to 75º in china clay. Since 1960, the consumption of
talc in the paper industry has greatly increased. Paper industry
requires talc powder, known as French chalk, of pure white quality. It
should be free from gritty material. It should have low CaCO3
content, not exceeding 4%; also FeO should not be more stha 2%.
Off-colour variety of talc free from grit is used for brown, roofing
or inferior type of paper. Soapstone bricks are used for lining pulp
tanks in the paper industry.
Textile industry also prefers talc powder free from grit and
colouration, which is used both for loading and bleaching certain
types of cotton goods. Inferior grades are used in back filling
In the manufacture of body and face powder, finely pulverized talc of
very high purity is required. The material is generally reduced to
fine particles by micronising. Cosmetics are prepared with a base of
talc to which are added covering agents like pigments and adhesives,
starches and perfumes. A common adhesive is zinc stearate. It is now
being fast substituted by lithium stearate. In the manufacture of
dentrifices some quantity of talc is used, here as a polishing agent.
Dentrifices are prepared by mixing suitable proportions of polishing
agents like talc, precipitated limestone, kaolin, calcium sulphate,
calcium phosphate with gum, glycerin, soap and other chemical
The pharmaceutical industry requires talc containing less than 0.1%
FeO. Natural material of such purity is generally not found and
pharmaceutical talc is preferred by passing the high purity powdered
talc over a magnetic separator to reduce the iron content.
In rubber industry talc is used for two purposes, one to prevent
rubber moulds from sticking and the other as compunding material in
the preparation of certain types of hard rubber. The consumption of
talc for the latter use is small. Generally grade II to III are used
in the rubber industry. Talc should be of fine mesh all passing
through 200 mesh.
Talc is increasingly being used in the manufacture of artwares, jars,
wall and floor tiles. It serves as a non-plastic ceramic material. The
addition of talc in suitable proportions in the body of mixtures for
porcelain, jars etc. prevents the crazing (cracking) effect on the
glazes. The proportion of talc in the ceramic body may go upto 80%. It
is valued for its refractoriness and stability, as well as extremely
low shrinkage at high temperature. Talc converts into clino-enstatite
at about 1300º C. Between 800ºC to 840ºC, the water
molecules are driven off and talc dissociates into enstatite and
amorphous silica without undergoing any change in shape, the shrinkage
being 0.0005 inch only.
In the manufacture of ceramic goods required for the electrical
industry, the talc should not contain more than 1.5% FeO and CaO. Some
consumers do not regard CaO as having any harmful effect.
Steatite suitable for the manufacture of 'lava' insulators must he
dense, compact, uniform and homogeneous intexture, free from any
inclusion and parting planes. It should not contain CaO more than 1.5%
; more than 1%. The iron oxide is a
colourant and gives the fired shapes an unattractive colour. An
increase of iron oxide above two per cent decreases the 'Q' value
(ratio of reactance to resistance) and increases the dielectric
constant. CaO imparts abrasiveness and usually a short vitrification
range and sometimes a high firing shrinkage.
In this industry, foliated, fibrous or lamellar talc of fine mesh
(300 mesh) is preferred. It is used as a paint or an extender in paint
industry. Colour, particle size and oil absorption are the main
criteria for selecting talc for paint manufacture. Talc suitability
for paint should have volatile matter below 0.75%, oil absorption
within 5 of the approved sample and solubility not more than 0.25% in
water. Asbestine is the trade name given to fibrous talc suitable for
A fair proportion of medium to inferior grades of talc is used in the
manufacture of perticides and insecticides. Talc is used here as a
carrier. Talc powder prevents infestation of food grains from
insectsand pests and hence it is sprinkled over food grains kept in
big godowns. Other uses are for making crayons for marking purposes
and for tailors' chalk.
Talc is mined in many countries. Some of the finest grades of
cosmetic and pharmaceutical talc are obtained from the Pyrenees in
France and the Alps in Italy. In Europe, Austria, France, Italy, and
Norway are the important producers and exporters. Canada is a small
producer with an average production of 23,000 tonnes annually from
Ontario and Quebec. A small production of talc is reported from five
provinces of Brazil, namely, Bahia, Mines Gerais, Parna, Rio de
Janeiro and Sao Paulo. Production from the Republic of Korea and
Brazil is of the same order as that of Canada. African countries are
also small producers. Production of talc in China and USSR is reported
to be 150,000 tonnes and 300,000 tonnes per annum respectively.
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