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LA GRAMMATICA DI ENGLISH GRATIS IN VERSIONE MOBILE   INFORMATIVA PRIVACY

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WIKIBOOKS
DISPONIBILI
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ART
- Great Painters
BUSINESS&LAW
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CARS
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MEDICINE
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LIFESTYLE
- Cosmetics
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TRADITIONS
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NATURE
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- Fruits And Vegetables



ARTICLES IN THE BOOK

  1. Academy Award for Makeup
  2. Aloe
  3. Alpha hydroxy acid
  4. Anti-aging cream
  5. Arenation
  6. Aromatherapy
  7. Artistry
  8. Astringent
  9. Beauty
  10. Beauty mark
  11. Beauty salon
  12. Camouflage Cosmetic
  13. Campaign for Safe Cosmetics
  14. Carnauba wax
  15. Castor oil
  16. Chanel No. 5
  17. Chemical peel
  18. Christian Dior
  19. Clinique
  20. Concealer
  21. Corpse paint
  22. Cosmeceutical
  23. Cosmetic advertising
  24. Cosmetics
  25. Cosmetology
  26. Creed
  27. Dermabrasion
  28. Dermatology
  29. Destination spa
  30. Eau de cologne
  31. Electrology
  32. Elizabeth Arden
  33. Essential oil
  34. Estée Lauder
  35. Estée Lauder Companies
  36. Estée Lauder pleasures
  37. Exfoliation
  38. Eye liner
  39. Eyeshadow
  40. Facial toning
  41. Glitter
  42. Glycerol
  43. Guerlain
  44. Hair
  45. Hair extension
  46. Helena Rubinstein
  47. Hermès
  48. History of cosmetics
  49. History of Perfume
  50. Hot tub
  51. INCI
  52. Jojoba oil
  53. Kohl
  54. Lancome
  55. Lip gloss
  56. Lip plumper
  57. Lipstick
  58. List of cosmetic ingredients
  59. L'Oréal
  60. Makeover
  61. Make-up artist
  62. Manicure
  63. Mascara
  64. Max Factor
  65. Max Factor, Sr.
  66. Maybelline
  67. Microdermabrasion
  68. Nail polish
  69. Natural skin care
  70. Noxzema
  71. Olay
  72. Pedicure
  73. Perfume
  74. Perfume bottles
  75. Permanent makeup
  76. Permanent wave
  77. Plastic surgeons
  78. Retinol
  79. Revlon
  80. Rimmel
  81. Rouge
  82. Shampoo
  83. Shaving
  84. Shaving cream
  85. Shea butter
  86. Shiseido
  87. Shower gel
  88. Skin Deep
  89. Skin whitening
  90. Soap
  91. Sunless tanning
  92. Sun tanning
  93. Surfactant
  94. Talcum powder
  95. Tanning bed
  96. Tanning lamp
  97. Thanaka
  98. The Body Shop
  99. Waxing
  100. Wella
  101. What Not to Wear

 


 

 
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    ENGLISHGRATIS.COM è un sito personale di
    Roberto Casiraghi e Crystal Jones
    email: robertocasiraghi at iol punto it

    Roberto Casiraghi           
    INFORMATIVA SULLA PRIVACY              Crystal Jones


    Siti amici:  Lonweb Daisy Stories English4Life Scuolitalia
    Sito segnalato da INGLESE.IT

 
 



COSMETICS
This article is from:
http://en.wikipedia.org/wiki/Talcum_powder

All text is available under the terms of the GNU Free Documentation License: http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License 

Talc

From Wikipedia, the free encyclopedia

(Redirected from Talcum powder)

Talc (derived from the Persian via Arabic talq) is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. It is sectile and very soft, with a hardness of 1 (Talc is the softest of the Mohs' scale of mineral hardness). It has a specific gravity of 2.5–2.8, a waxlike or pearly luster, and is translucent to opaque. Its colour ranges from white to gray or green and it has a distinctly greasy feel. Its streak is white.

Formation

Talc is a metamorphic mineral resulting from the metamorphism of magnesian minerals such as pyroxene, amphibole, olivine and other similar minerals in the presence of carbon dioxide and water. This is known as talc carbonation or steatization and produces a suite of rocks known as talc carbonates.

Talc is primarily formed via hydration and carbonation of serpentine, via the following reaction;

Serpentine + Carbon Dioxide → Talc + Magnesite + Water

2Mg_3Si_2O_5(OH)_4 + 3CO_2 \rarr Mg_3Si_4O_{10}(OH)_2 + 3MgCO_3 + 3H_2O

Talc can also be formed via a reaction between dolomite and silica, which is typical of skarnification of dolomites via silica-flooding in contact metamorphic aureoles;

Dolomite + Silica + Water → Talc + Calcite + Carbon Dioxide

3CaMg(CO_3)_2 + 4SiO_2 + H_2O \rarr Mg_3Si_4O_{10}(OH)_2 + 3CaCO_3 + 3CO_2

Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism via the following reaction:

Chlorite + Quartz → Kyanite + Talc + H2O

In this reaction, the ratio of talc and kyanite is dependant on aluminium content with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, glaucophane within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as whiteschist.

Occurrence

Talc is a very common metamorphic mineral in metamorphic belts which contain ultramafic rocks, such as soapstone (a high-talc rock), and within whiteschist and blueschist metamorphic terranes. Prime examples of whiteschists include the Franciscan Metamorphic Belt of the western United States, the western European Alps especially in Italy, certain areas of the Musgrave Block, and some collisional orogens such as the Himalayas.

Talc carbonated ultramafics are typical of many areas of the Archaean cratons, notably the komatiite belts of the Yilgarn Craton in Western Australia. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guyana Shield, and from the ophiolite belts of Turkey, Oman and the Middle East.

Notable economic talc occurrences include the Mount Seabrook talc mine, Western Australia, formed upon a polydeformed, layered ultramafic intrusion.

Uses

Talcum Powder
Talcum Powder

A coarse grayish-green high-talc rock is soapstone or steatite and has been used for stoves, sinks, electrical switchboards, etc. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a diaper (see diaper rash). Most tailor's chalk is talc, as is the chalk often used for welding or metalworking.

Talc is also used as food additive or in pharmaceutical products. In the European Community the additive number is E553b.

Safety

Several studies have established preliminary links between talc and pulmonary issues,[1] lung cancer,[2][3] skin cancer and ovarian cancer.[4] This is a major concern considering talc's widespread commercial and household use. However, no conclusive study has yet been made to determine either the toxicity and/or carcinogenic nature of talc and the long history of safe use suggests that these concerns are unfounded. The U.S. Food and Drug Administration (FDA) considers non-asbestiform talc, that is talc which does not contain potentially carcinogenic asbestiform amphibole fibers, to be Generally recognized as safe (GRAS) for use in cosmetics.

See also

Wikimedia Commons has media related to:
Talc
  • List of minerals
  • Serpentinite
  • Talc carbonate
  • Magnesite
  • Blueschist
  • Metamorphic rocks
  • Asbestos
  • Links to external chemical sources

References

  • mineral.galleries.com
  • webmineral.com
  • www.mindat.org
  1. ^ Hollinger (1990). "Pulmonary toxicity of inhaled and intravenous talc.". 
  2. ^ National Toxicology Program (1993). "NTP Toxicology and Carcinogenesis Studies of Talc (Non-Asbestiform) in Rats and Mice (Inhalation Studies).". 
  3. ^ NIOSH Worker Notification Program. "Health effects of mining and milling talc.". (historical)
  4. ^ Harlow, Cramer, Bell, et al. (1992). "Perineal exposure to talc and ovarian cancer risk.". 
Retrieved from "http://en.wikipedia.org/wiki/Talc"