Muscovite
Muscovite | |
---|---|
Star-shaped twinned muscovite crystals from Minas Gerais , Brazil (size 5.9 cm × 5.1 cm × 3.6 cm) | |
General and classification | |
other names |
|
chemical formula | KAl 2 [(OH, F) 2 | AlSi 3 O 10 ] |
Mineral class (and possibly department) |
Layered silicates (phyllosilicates) - mica group - celadonite-muscovite series |
System no. to Strunz and to Dana |
9.EC.15 ( 8th edition : VIII / H.10) 71.02.02a.01 |
Similar minerals | Lepidolite , paragonite , talc |
Crystallographic Data | |
Crystal system | monoclinic or trigonal |
Crystal class ; symbol | see modifications |
Space group | see crystal structure |
Frequent crystal faces | {001}, {110}, more rarely {010} and {111} |
Twinning | Twin axis [310], twin plane (001) and formation of 6-pointed stars; Oriented adhesions with biotite and other mica |
Physical Properties | |
Mohs hardness | 2.5 parallel [001]; parallel [001] |
Density (g / cm 3 ) | measured: 2.77 to 2.88; calculated: 2.83 |
Cleavage | very perfect after {001} |
Break ; Tenacity | uneven |
colour | colorless, yellowish, brownish, rarely reddish, greenish |
Line color | White |
transparency | transparent to translucent |
shine | Glass gloss, mother-of-pearl, matt |
radioactivity | hardly measurable |
Crystal optics | |
Refractive indices |
n α = 1.552 to 1.576 n β = 1.582 to 1.615 n γ = 1.587 to 1.618 |
Birefringence | δ = 0.035 to 0.042 |
Optical character | biaxial negative |
Axis angle | 2V = 2v x = 30 ° to 47 ° |
Pleochroism | weak, colorless or bluish-greenish-yellow-bluish-green |
Other properties | |
Chemical behavior | Not soluble in HCl or H 2 SO 4 |
Special features | rare pleochroic halos around zirconium inclusions |
Muscovite (also muscovite , clay mica , cats silver , Antonit , Mrs. Glass , potassium mica ) is a very common mineral from the mica group within the mineral class of " silicates and Germanates ". Depending on the modification, it crystallizes in the monoclinic or trigonal crystal system with the general chemical composition KAl 2 [(OH, F) 2 | AlSi 3 O 10 ]. Structurally, it belongs to the layered silicates .
Muscovite usually develops tabular, leafy, scaly crystals , but also massive aggregates in yellowish, brownish, reddish or greenish color. Colorless crystals are also known. More rarely, but in meter-sized crystals, muscovite also occurs pseudo-hexagonally, i.e. the crystal form shows an apparently hexagonal symmetry through twinning .
Its cleavage is very perfect and the split sheets are elastically flexible. This property, which it has in common with dark mica ( biotite ), can give rocks a slatey structure.
Etymology and history
Muscovite means something like Moscow glass in Russian and was so named by James Dwight Dana in 1850 because it occurs in Russia in large, coarse-leaved aggregates and was previously used for glazing windows and images of saints. Due to its heat resistance, it is also very suitable as a protective glass for furnace windows .
classification
In the 8th edition of the mineral systematics according to Strunz , which is now outdated, but still in use , muscovite belonged to the division of "phyllosilicates", where together with celadonite the "celadonite-muscovite series (Phengite)" with the system no. VIII / H.10 and the other members aluminoseladonite , boromuscovite , chromophyllite , chromium seladonite , ferro-aluminoseladonite , ferroseladonite , ganterite , nanpingite , paragonite , roscoelite and tobelite .
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 muscovite in the category of "phyllosilicates". This is, however, further subdivided according to the crystal structure, so that the mineral, according to its structure, can be found in the sub-section "Layered silicates (phyllosilicates) with mica tablets, composed of tetrahedral or octahedral networks", where the sole namesake is the "Muscovite group" with the system No. 9.EC.15 and the other members aluminoseladonite, boromuscovite, celadonite, chernykhite, chrome seladonite, chrome phyllite, ferro-aluminoseladonite, ferro-aluminoseladonite, ferroseladonite, ganterite, montdorite, nanpingite, paragonite, roscoelite, tainiolite and tobelite.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also classifies muscovite into the “layered silicate minerals” section. Here he is a member and namesake of the " mica group (muscovite subgroup) " with the system no. 71.02.02a can be found in the subsection “ Layered Silicates: Layers of six-membered rings with 2: 1 layers”.
Crystal structure
Muscovite crystallizes polytype in monoclinic symmetry , which are designated as muscovite-1M , muscovite-2M 1 and muscovite-2M 2 , as well as in trigonal symmetry with the designation muscovite-3T and in triclinic symmetry with the designation muscovite-2A .
Polytype | Crystal system | Space group | Lattice parameters and formula units per unit cell (Z) |
---|---|---|---|
Muscovite 1M | monoclinic | C 2 / m (No. 12) | a = 5.21 Å ; b = 8.99 Å; c = 10.27 Å and β = 101.6 ° and Z = 2 |
Muscovite-2M 1 | C 2 / c (No. 15) | a = 5.20 Å ; b = 9.03 Å; c = 20.11 Å and β = 95.8 ° and Z = 4 | |
Muscovite-2M 2 | C 2 / c (No. 15) | a = 8.96 Å ; b = 5.17 Å; c = 20.31 Å and β = 100.7 ° and Z = 4 | |
Muscovite 3T | trigonal | P 3 1 12 (No. 151) or P 3 1 21 (No. 152) | a = 5.21 Å and c = 29.8 Å and Z = 3 |
Muscovite 2A | triclinic | C 1 (No. 2, position 3) | a = 5.19 Å ; b = 9.01 Å; c = 20.04 Å; α = 90.0 °; β = 95.7 ° and γ = 90.0 ° and Z = 4 |
Modifications and varieties
Muscovite is a collective name for the modifications :
- Muscovite 2M 1 - monoclinic prismatic - 2 / m (C 2h )
- Muscovite-1M , also muscovite-2Md - monoclinic
- Muscovite 3T - trigonal
The following varieties are known so far
- Alurgite - red due to the inclusion of manganese
- Astrolite - white to yellow
- Damourite - pseudomorphism according to topaz or corundum
- Fuchsite - due to a low chromium content (1 to 5%), flaky, green shimmering aggregate (named after the chemist and mineralogist Johann Nepomuk von Fuchs )
- Gilbertite - massive aggregate
- Margarodit - contains sodium and calcium
- Mariposit - contains up to one percent chromium
- Phengite - contains a lot of silica
- Pinite - pseudomorphism after cordierite
- Pinitoid - pseudomorphism according to potassium feldspar
- Sericite (also Sericite ) - fine-grained or finely flaky muscovite or paragonite aggregate (grain size <0.1 mm)
Education and Locations
Muscovite is an important rock-forming mineral and is formed through metamorphosis , especially in mica slate or gneiss , but also magmatic in granite or pegmatite , where it can form crystals of up to 5 meters and 85 tons, such as those found in the Inikurti mine “ Emerged at Nellore in India. It occurs in many acidic deep rocks and crystalline slates , but not in effluent rocks . Weathered it, the result is by releasing potassium , a clay mineral , the illite or Hydromuskovit is called. As accompanying minerals occur, inter alia, alkali feldspar and plagioclase , biotite , quartz , topaz and tourmaline , as well as ore minerals spodumene , Amblygonit , cassiterite and Tantalit- (Mn) on.
Muscovite can be found in many places around the world, with around 13,000 known sites so far (as of 2013).
In Germany, the mineral was found in many places in the Bavarian Forest (Bodenmais, Drachselsried, Vilshofen), in the Eifel (Ettringen, Niedermendig, Niederzissen), in the Eppstein slate of the Vordertaunus , in the Ore Mountains (Ehrenfriedersdorf, Freiberg, Oberlausitz), in Fichtelgebirge (Tröstau, Weißenstadt), in the Harz (Bad Harzburg), in the Münchberger Gneismasse , in the Upper Palatinate Forest (Waidhaus), in the Odenwald (Reichelsheim), in the Black Forest (Hornberg, Wittichen), in the Siegerland , in the Spessart , in the Thuringian Forest ( Gottlob, Henneberg) and in Vogtland (Lengenfeld).
In Austria, muscovite has so far been found mainly in Carinthia (Hüttenberg, Gurktal Alps, Hohe Tauern), Salzburg (Nassfeldtal, Habachtal, Untersulzbachtal), Styria (Fischbacher Alpen, Koralpe) and Tyrol (Kalstal, Zemmgrund, Zillertal).
In Switzerland, the mineral was found mainly in the cantons of Graubünden (front and rear Rhine valleys), Ticino (Valle Maggia, Valle Leventina) and Valais (Binn valley).
Beautifully developed crystal steps of up to 10 centimeters in size are also known from the Alabashka pegmatites near Murzinka ( Sverdlovsk Oblast ) in the Urals.
Almost transparent Muskovitscheibe with hematite - inclusions from Chandler's Hollow, Delaware ( total size of 32.0 cm x 22.9 cm x 0.2 cm )
Smoky quartz and muscovite on microcline from the "Little Three Mine", San Diego County , California (size 6.8 cm × 6.8 cm × 2.4 cm)
use
Because of its good thermal and electrical insulation, muscovite is an important raw material in the technical industry. In the past it was also often used for heat-resistant furnace windows and in Russia for glazing ( Moscow glass ).
Finely ground it serves (also with other types of mica) as a filler and for the internal reinforcement of coating systems. Fillers based on muscovite mica have a wide range of particle sizes, ranging from 0.001 mm to 0.5 mm. In cosmetics , muscovite is used together with biotite in lipsticks and other cosmetics to give it a long-lasting shine.
The variety fuchsite (chrome muscovite) served as a green pigment in painting and is known for its use in Indian art objects from Guatemala . It is also processed into jewelry.
See also
literature
- James Dwight Dana : Mica Family: Muscovite In: A System of Mineralogy 3rd edition, George P. Putnam, New York 1850, pp. 356–358 ( PDF 254.4 kB )
- Helmut Schrätze , Karl-Ludwig Weiner : Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 814 .
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 250 .
Web links
- Mineral Atlas: Muscovite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Muskovite
- Mineral Lexicon - Muscovite
- Kremer pigments - fuchsite as a green pigment
- Webmineral - Muscovite (English)
- Muscovite in the nature lexicon
Individual evidence
- ↑ a b c 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. 221 .
- ↑ Christof Exner: About Muskowit-Epidot-Albitkornbildung in Mauthausen Granite In: Tschermaks mineralogische und petrographische Mitteilungen Volume 4, Kapitel 1, 1954, S. 312-319 doi: 10.1007 / BF01140402
- ↑ Haymo Heritsch: The conditions of formation of the garnet-thistle-paragonite-muskowite-mica slate from Gaberl, Stubalpe, Weststeiermark In: Mitteilungen Naturwissenschaftlicher Verein für Steiermark Volume 113, Graz 1983, pp. 5-14 ( PDF 2.3 MB )
- ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 814 .
- ↑ a b c d Muscovite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 70.9 kB )
- ↑ a b c d Mindat - Muscovite
- ^ 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. 664-665 .
- ↑ The numbering of this axis position does not correspond to the order of the International Tables for Crystallography , because it is not listed there.
- ↑ a b Udo Neumann: Mineral adhesions (polymorphisms, para- and pseudomorphoses, epitaxies and twin formations) ( Memento from November 13, 2011 in the Internet Archive ). (University of Tübingen).
- ↑ a b Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 250 .
- ↑ Mindat - Number of localities for muscovite
- ↑ Michaela Winkelmann: Palynostratigraphic investigations on the southern edge of the Rhenish Slate Mountains (southern Taunus, southern Hunsrück). Herbert Utz Verlag, 1997, chapter 1.5.1.2 Eppsteiner slate series, p. 9 PDF
- ↑ wirtz-hattersheim.de: Natursteinwerk Fischbach , Fischbach (Taunus)
- ↑ a b c List of places where muscovite was found in the Mineralienatlas and Mindat
- ↑ Detlev Gysau, fillers, technology of coating . Vincentz, Hannover 2006 (§ 5.2.3 Glimmer)