Talc is a mineral with perfect cleavage and soapy feel, which occurs as foliated to fibrous masses and some times in coarsely granular, finely granular, or cryptocrystalline masses.
TALC
Synonym
French chalk, Talcum.
Source
Talc is a mineral with perfect cleavage and soapy feel,
which occurs as foliated to fibrous masses and some times in coarsely granular,
finely granular, or cryptocrystalline masses.
Geographical Source
It is found in Austria, Canada, United States (California,
Montana, Texas, etc.), France and also in Italy.
History
The origin of the name Talc came from Persian through Arabic
talc. India has also been successfully exporting talc to overseas. The Indian
talc industry hopes to have joint venture partnerships with international
business houses with technical proficiency in the beneficiation and
sterilization of talc.
Description
It is folia which is slightly flexible and is not elastic.
It has perfect basal cleavage. Talc is very soft and sectile in nature, with a
hardness of 1. It is the softest known solid. Talc is translucent to opaque and
has specific gravity of 2.5–2.9. The colour of talc ranges from white to grey
to green. The lubricating property, high luster and low conductivity to
electricity and to heat determine its industrial value. Talc is chemically
inert, sparingly soluble in dilute mineral acid and insoluble in water. It has
no taste and odour.
Microscopy
Talc powder when observed under microscope shows colourless,
irregular, and sharply angular in nature.
Chemical Constituents
Talc composed of hydrated magnesium silicate with the
chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2
and usually consist of small quantities of nickel, iron and aluminium as
impurities. The variation of colour of talc to greenish or greyish tint
indicates the presence of iron oxide.
Chemical Tests
Fuse about 0.5 g talc with 0.2 g each of anhydrous sodium
carbonate and potassium carbonate in a platinum crucible. Dissolve the fused
mixture into 50 ml of water and to it add hydrochloric acid and until it ceases
to effervescence. Add little more acid and evaporate the contents to dryness on
water bath. Cool it, dissolve in 20 ml of water, boil, and filter. To the
filtrate, add about 2 g of ammonium chloride and 5 ml of diluted ammonia
solutions. Remove the precipitate formed, if any by filtration. To the
filtrate, add sodium phosphate, white crystalline precipitate of magnesium
ammonium carbonate is formed.
2. Yields the reactions characteristic of silicate.
Uses
Talc is used as a cosmetic (talcum powder), as a lubricant,
as a dusting powder for coating and dusting pills and as a filler in paper
manufacture. It is used as astringent in baby powders for the prevention of
rashes in area covered with dipper. Talc is used in making paper (as a filler),
soap, lubricants, electrical insulation stoves, sinks. It is used as a filter
aid for filtration and clarification of cloudy liquids.
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