|
'''Талк''' (изведено из персијског преко арапског ''talq'') је [[минерал]] по саставу [[хидрат|хидратисани]] [[магнезијум]] [[силикат]] формуле [[Водоник|H]]<sub>2</sub>[[Магнезијум|Mg]]<sub>3</sub>([[Силикат|SiO]]<sub>3</sub>)<sub>4</sub> или Mg<sub>3</sub>[[Силицијум|Si]]<sub>4</sub>[[Кисеоник|O]]<sub>10</sub>([[Хидроксид|OH]])<sub>2</sub>.
<!--It occurs as foliated to fibrous masses, its [[monoclinic]] [[crystal]]s being so rare as to be almost unknown. It has a perfect [[basal cleavage]], and the folia are non-[[elastic (solid mechanics)|elastic]], although slightly flexible. It is [[sectile]] and very soft, with a [[Mohs scale of mineral hardness|hardness]] of 1 (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 (color)|gray]] or [[green]] and it has a distinctly greasy feel. Its streak is white.-->
== Настанак==
Талк такође може да настане у реакцији доломита и силицијумдиоксида:
<!--
Talc can also be formed via a reaction between dolomite and silica, which is typical of [[skarn]]ification of dolomites via silica-flooding in contact metamorphic aureoles;-->
''[[Доломит]] + [[Силицијум диоксид]] + вода → Талк+ [[Калцит]] + Угљен диоксид''
:<math>3CaMg(CO_3)_2 + 4SiO_2 + H_2O \rarr Mg_3Si_4O_{10}(OH)_2 + 3CaCO_3 + 3CO_2</math>
<!--Talc can also be formed from magnesian chlorite and quartz in [[blueschist]] and [[eclogite]] metamorphism via the following reaction:
-->
''[[Хлорит]] + [[Кварц]] → [[Кијанит]] + Талк+ H<sub>2</sub>O''
<!--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 [[fengite|phengite]], [[garnet]], [[glaucophane]] within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as ''whiteschist''.-->
== Налажење==
<!--Talc is a very common metamorphic mineral in metamorphic belts which contain [[ultramafic rock]]s, 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 [[Orogeny|orogens]] such as the [[Himalayas]].-->
<!--[[Talc carbonate]]d ultramafics are typical of many areas of the [[Archaean]] [[craton]]s, notably the [[komatiite]] belts of the [[Yilgarn craton|Yilgarn Craton]] in [[Western Australia]]. Talc-carbonate ultramafics are also known from the [[Geology of Australia|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.-->
== Употреба==
[[Слика:Talcum Powder.JPEG|мини|Талков прах]]
<!--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 [[Cosmetics|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.
{{SectOR}}-->
<!--Talcum powder has also become widely used as a stretching substance for [[marijuana]].{{Fact|date=February 2007}} The harvested buds are mixed with the talcum powder so it sticks to the resin. This is done to increase the weight as well as to make it look more potent. The dried resin itself has a similar crystal-like appearance. Marijuana stretched with talcum poses several health threats, short-term damage (pneumonia), and possibly even long-term damage (lung tissue [[granuloma]]) caused by inhaling the talcum vapors.{{Fact|date=February 2007}}-->
== Сигурност==
|title=Perineal exposure to talc and ovarian cancer risk.
|author=Harlow, Cramer, Bell, et al. |year=1992}}
</ref>
</ref> <!--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 [[carcinogen]]ic [[asbestos|asbestiform]] [[amphibole]] fibers, to be [[Generally recognized as safe]] (GRAS) for use in cosmetics.-->
==Види још==
* [[Листа минерала]]
<!--* [[Serpentinite]]
* [[Talc carbonate]]
* [[Magnesite]]
* [[Blueschist]]
* [[Metamorphic rocks]]
* [[Asbestos]]-->
== Литература==
* [http://www.mindat.org/min-3875.html www.mindat.org]
<references/>
[[Категорија:Минерали]]
<!--[[Категорија:Phyllosilicates]]
[[Категорија:Magnesium minerals]]
[[Категорија:Symbols of Vermont]]
-->
[[ar:تلك]]
| 