Chrysotile

• Chrysotile asbestos
• Faserserpentin
• White asbestos or chrysotile asbestos

• Mg3Si2O5 (OH) 4
• Mg6 [( OH) 8 | Si4O10 ]

Chrysotile, also known as white asbestos or Faserserpentin, is a commonly occurring mineral from the group of serpentine within the mineral class of " silicates and Germanates ". Chrysotile structurally is one of the layered silicates with the chemical composition Mg3Si2O5 (OH) 4, wherein between two crystallographic orientations or crystal systems of the individual layers can be distinguished ( Polytypism ):

• Klinochrysotil oriented monoclinic
• Orthochrysotil and Parachrysotil oriented orthorhombic, but differ in their lattice parameters.

The complex crystal structure results in the chrysotile to the fact that the cylindrical layers curl up and long form fine and inside hollow fibers. This fused to felt or mat-like aggregates, and are generally known under the collective term asbestos. The color of chrysotile usually varies between light and dark green, but also occurs in pale yellow to gray - brown or yellow tones.

Chrysotile is next to lizardite and antigorite part of the rock serpentinite.

Etymology and history

Was first discovered chrysotile near Złoty Stok ( Hory ) in the Polish Lower Silesian Voivodeship and described in 1834 by Franz von Hess Peter, of the mineral inspired by the golden glow of some samples after the Greek words χρυσός [ Chrysos ] for " Gold" and τίλος [ tilos ] for " fiber ", thus assembled " gold fiber" named.

The asbestos ( ancient Greek: ἄσβεστος [ asbestos ] " imperishable " or for " incombustible " ), including the chrysotile hearing, and their property, not to burn even at high temperatures in the fire, however, was already known in ancient Greece.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz chrysotile belonged to the general ward of the " layer silicates ( phyllosilicates ) ," where he, along with amesite, antigorite, berthierine, Brindleyit, Carlosturanit, Cronstedtit, Dozyit, fraipontite, Greenalith Karpinskit, Karyopilit, Kellyit, lizardite, and Népouit Pecorait the " serpentine " with the system no. VIII/H.27 formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the chrysotile also in the department of " phyllosilicates " one. However, this is further subdivided according to the type of film formation, so that the mineral according to its construction in the subsection " layer silicates ( phyllosilicates ) with kaolinite layers composed of tetrahedral or octahedral networks " is to find out where he is also in the " serpentine " with System no. 9.ED.15 and the other members amesite, antigorite, berthierine, Brindleyit, Cronstedtit, fraipontite, Greenalith, Karyopilit, Kellyit, lizardite, Manandonit, Népouit and Pecorait be found.

The mainly common in English-speaking classification of minerals according to Dana assigns the chrysotile in the department of " layer silicate minerals " one. Here, the " serpentine " is, however, divided into several subgroups and chrysotile is named after the " chrysotile subgroup " with the system no. 71.01.02d within the subdivision " layer silicates: layers of six-membered rings with 1:1 layers ".

Education and Locations

Like all Serpentine is also produced in the conversion of chrysotile secondary magnesium- rich olivine in peridotite orthopyroxenes or. Accompanying minerals occur among others lizardite and corundum.

Worldwide, so far (as of 2012) about 900 localities known as. Apart from its type locality Złoty Stok chrysotile could be found in Poland nor in Nasławice, Sobotka, Rędziny and at several points near Ząbkowice Śląskie ( Frankenstein ) in Lower Silesia and in the vicinity of Dębnik and Dubie near Krzeszowice in powiat Krakowski ( Lesser Poland Voivodeship ).

In Germany, chrysotile has been found so far, especially in Bavaria, so among other things, in the so-called Münchberger mass, but also on Teichel mountains, on Zeilberg. In addition, chrysotile yet occurred in some places in the Black Forest (Baden- Württemberg), Odenwald (Hesse), at Backsberg and Bad Harzburg in Lower Saxony, in the pit Kuhle (North Rhine - Westphalia) and in some places in Saxony (eg width Brunn and Freiberg in the Ore Mountains ) on.

Even in rock samples from the Mid-Atlantic Ridge ( hydrothermal field " Logatchev 1" and " Markov - depth ," Sierra Leone Fracture Zone ) and from the Mariana Trench in the western Pacific Ocean chrysotile could be detected.

Known assisted areas

A very significant mineral deposit in Russia is Ak - Dowurak in Siberia, where a largest asbestos mines in the world was operated in the open pit. Also in the Urals are many important Chrysotilasbestlagerstätten as the city asbestos, which was named after its eponymous industry.

Another important mining area is the Canadian province of Quebec. Since asbestos in Canada may not be used itself, annually 200,000 tons are exported to developing countries such as India, Indonesia and Thailand. This practice is supported by lobbyists for the asbestos industry as Clement Godbout, Head of the " White Asbestos Institute " in Montreal. The MP Pat Martin of the Social Democratic parliamentary faction fights a general delivery stop in Canada. Critics of export practice find that in the countries in which is exported, the conditions for the safe handling of the substance are not given.

In South Africa, among others, Barberton, the Havelock Asbestos Mine in the district Hhohho in Swaziland and Zvishavane significant (formerly Shabani ) in Zimbabwe producers of chrysotile asbestos.

Synthetic production

Chrysotile can be derived from a mixture of (poly ) - silica and magnesium oxide in water at 300 ° C and 90-160 bar pressure to produce.

Crystal structure

Chrysotile consisting of silica tetrahedra which eckenverknüpft define a plane. The Sechsecklücken be in the first layer occupied by hydroxide ions (red), followed by a second layer of hydroxide ions (green), which span an octahedral space. These octahedral space different cations can be incorporated, resulting in the plurality of Serpentinasbeste. In the case of chrysotile is magnesium.

Use

Chrysotile has been used for heat-resistant materials such as heat-resistant clothing, electrical insulation, gaskets and ropes. Furthermore, it was used for roof panels ( Eternit plates). Due to the dangers of asbestos ( asbestosis caused by inhaling asbestos dust ), it is now rarely used.

According to the EU Regulation (EC ) No 1907/2006 ( REACH ) is the marketing and use of chrysotile and products containing chrysotile, is prohibited.