Chrysotile
| Chrysotile | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula |
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Mineral class (and possibly department) |
Layered silicates (phyllosilicates) - serpentine group |
|
System no. to Strunz and to Dana |
9.ED.15 ( 8th edition : VIII / H.27) 71.01.02d.00 |
| Crystallographic Data | |
| Crystal system | monoclinic or orthorhombic |
| Crystal class ; symbol | see crystal structure |
| Space group | see crystal structure |
| Lattice parameters | see crystal structure |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2 to 3 |
| Density (g / cm 3 ) | 2.53 to 2.65 |
| Cleavage | good to perfect, frayed in the finest threads |
| Break ; Tenacity | shell-like, splintery, tough |
| colour | white, various shades of green or gray-yellow to gray-brown |
| Line color | White |
| transparency | translucent to opaque |
| shine | Resin gloss, silk gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.569 n γ = 1.570 |
| Birefringence | δ = 0.001 |
| Optical character | biaxial |
Chrysotile , also known as fiber serpentinite , picrosmin or white asbestos , is a frequently occurring mineral from the serpentine group within the mineral class of " silicates and germanates ". Structurally, chrysotile belongs to the layered silicates with the chemical composition Mg 3 Si 2 O 5 (OH) 4 , whereby a distinction can be made between two crystallographic orientations or crystal systems of the individual layers ( polytype ):
- Klinochrysotil is monoclinic aligned
- Orthochrysotile and Parachrysotile are aligned orthorhombically , but differ in their lattice parameters .
The complex crystal structure of chrysotile means that the layers roll up cylindrically and form long, fine fibers that are hollow on the inside. These grow together to form felt or mat-like aggregates and are generally known under the collective name of asbestos . The color of chrysotile usually varies between light and dark green, but also comes in light yellow to gray or brownish yellow shades.
Besides lizardite and antigorite, chrysotile is part of serpentinite .
Etymology and history
Chrysotile was first discovered near Złoty Stok ( Reichenstein ) in the Prussian province of Silesia (today the Polish Voivodeship of Lower Silesia ) and described in 1834 by Franz von Kobell , who named the mineral based on the golden sheen of some samples after the Greek words χρυσός chrysós , German 'gold ' and τίλος tilos , German ' fiber ' , put together so called' gold fiber ' .
The asbestos (ancient Greek: ἄσβεστος asbestos , German 'immortal' or 'incombustible'), to which the chrysotile belongs, and their property of not burning in the fire even in great heat, were already known in ancient Greece .
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz chrysotile was part of the general department of "phyllosilicates (phyllosilicates)" where he collaborated with Amesit , antigorite , berthierine , Brindleyit , Carlosturanit , Cronstedtit , Dozyit , Fraipontite , Greenalith , Karpinskit , Karyopilit , Kellyit , Lizardit , Népouit and Pecorait the "serpentine group" with the system no. VIII / H.27 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies chrysotile in the “phyllosilicates” department. This is, however, further subdivided according to the type of layer formation, so that the mineral, according to its structure, can be found in the subsection "Layered silicates (phyllosilicates) with kaolinite layers , composed of tetrahedral or octahedral networks", where it can also be found in the "serpentine group" with the System no. 9.ED.15 and the other members Amesit, antigorite, berthierine, Brindleyit, Cronstedtit, Fraipontite, Greenalith, Karyopilit, Kellyit, Lizardite, Manandonit , népouite and Pecorait be found.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , classifies the chrysotile in the "layered silicate minerals" department. Here, however, the "serpentine group" is divided into several subgroups and Chrysotile is the namesake of the " Chrysotile subgroup " with the system no. 71.01.02d within the subdivision “Layered Silicates: Layers of six-membered rings with 1: 1 layers”.
Education and Locations
Like all serpentines, chrysotile is also secondary to the conversion of magnesium-rich orthopyroxenes or olivines into peridotites . Lizardite and corundum appear as accompanying minerals .
Worldwide, around 900 sites are known to date (as of 2012). In addition to its type locality Złoty Stok, Chrysotil could also be found in Poland near Nasławice , Sobótka , Rędziny and in several places near Ząbkowice Śląskie ( Frankenstein ) in Lower Silesia and in the vicinity of Dębnik and Dubie near Krzeszowice in the Krakowski powiat (Lesser Poland Voivodeship).
In Germany, chrysotile has so far been found mainly in Bavaria, including in the so-called Münchberger Masse , but also on the Teichelberg , on the Zeilberg . Furthermore, chrysotile occurred in some places in the Black Forest (Baden-Württemberg), Odenwald (Hesse), at Backenberg and near Bad Harzburg in Lower Saxony, in the Kuhlenberg mine (North Rhine-Westphalia) and in some places in Saxony (e.g. Breitenbrunn and Freiberg in the Ore Mountains).
Chrysotile could also be detected 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.
Known funding areas
A very important deposit in Russia is located near Ak-Dowurak in Siberia, where one of the largest asbestos mines in the world was operated in open-cast mining . There are also many important chrysotile asbestos deposits in the Urals , such as the city of Asbestos , which was named after its industry of the same name.
Another important mining area is the Canadian province of Québec . Since asbestos is no longer allowed to be used in Canada itself, 200,000 tons are exported annually to developing countries such as India, Indonesia and Thailand. This practice is supported by lobbyists in the asbestos industry such as Clement Godbout, director of the “White Asbestos Institute” in Montreal . The MP Pat Martin from the social democratic parliamentary group is fighting against a general subsidy freeze in Canada. Critics of export practice state that the countries to which exports are made do not meet the requirements for safe handling of the substance.
In South Africa, Baberton , the Havelock asbestos mine in the Hhohho district in Swaziland and Zvishavane (formerly Shabani ) in Zimbabwe were important producers of chrysotile asbestos.
Synthetic manufacture
Chrysotile can be produced from a mixture of (poly) silica and magnesium oxide in water at 300 ° C and 90–160 bar pressure.
Crystal structure
Chrysotile is composed of silica - tetrahedra which shares corners define a plane. The hexagonal gaps are filled with hydroxide ions (red) in the first layer , followed by a second layer of hydroxide ions (green), which define an octahedral space. Various cations can be stored in this octahedral space , which leads to the multitude of serpentine bests. In the case of chrysotile, it is magnesium .
| Surname | Clinochrysotile | Orthochrysotile | Parachrysotile |
|---|---|---|---|
| Crystal system | monoclinic | orthorhombic | orthorhombic |
| Crystal class | 2 / m | mm 2 | not defined |
| Space group | C 2 / m (No. 12) | Ccm 2 1 (No. 36, position 2) | not defined |
|
Lattice constants of the unit cell |
a = 5.34 Å b = 9.25 Å c = 14.65 Å β = 93.3 ° |
a = 5.34 Å b = 9.20 Å c = 14.63 Å |
a = 5.30 Å b = 9.24 Å c = 14.70 Å |
| Number of formula units in the unit cell |
2 | 2 | 2 |
use
Chrysotile was used for heat-resistant materials such as heat-resistant clothing , electrical insulation , seals and ropes . It was also used for roof panels ( Eternit panels). Due to the dangers posed by asbestos ( asbestosis due to inhalation of asbestos dust) it is rarely used today.
As an asbestos mineral , actinolite ( CAS numbers 12001-29-5 and 132207-32-0) is one of the dangerous substances whose production, placing on the market or use in the EU is restricted or prohibited in accordance with Annex XVII of the REACH regulation .
See also
literature
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 573-576 .
- Helmut Schrätze , Karl-Ludwig Weiner : Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 845 ( chrysotile asbestos ) .
- Clinochrysotile . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 70 kB ; accessed on August 12, 2020]).
- Orthochrysotile . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 62 kB ; accessed on August 12, 2020]).
- Parachrysotile . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 61 kB ; accessed on August 12, 2020]).
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th, completely revised and updated edition. Springer, Berlin [a. a.] 2005, ISBN 3-540-23812-3 , pp. 105-106 .
Web links
- Mineralienatlas (Wiki): Klinochrysotil - Orthochrysotil - Parachrysotil
- Mindat: Clinochrysotil - Orthochrysotile - Parachrysotile (English)
- Webmineral: Clinochrysotil - Orthochrysotile - Parachrysotile (English)
- Information on harmful substances on chrysotile asbestos at enius.de
Individual evidence
- ↑ a b c d Chrysotile at geo-archiv.de
- ↑ Thomas Nowak (asbestos expert): Chrysotile asbestos, white asbestos, serpentine asbestos
- ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2020, accessed August 12, 2020 .
- ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ^ A b c Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 677 .
- ^ A b Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 218 .
- ↑ Hellmuth Bögel: Knaurs Mineralienbuch. The house and handbook for friends and collectors of minerals . Droemer Knaur, Munich 1972, ISBN 3-426-00292-2 , p. 214 .
- ↑ a b c Mindat - Chrysotile
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 318 .
- ↑ Find location list for chrysotile in the Mineralienatlas and Mindat
- ↑ dradio.de, accessed July 18, 2012
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 761–763 (first edition: 1891).
- ↑ List of restricted substances - Annex XVII of the REACH regulation: Asbestos, chrysotile. In: echa.europa.eu. European Chemicals Agency (ECHA), accessed August 12, 2020 .
- ↑ Regulation (EC) No. 1907/2006 of the European Parliament and of the Council. (PDF 1.97 MB) In: eur-lex.europa.eu. December 30, 2006, p. 401 , accessed on August 12, 2020 ( Official Journal of the European Union L 396).