Editing Muscovite (section)

{{Short description|Hydrated phyllosilicate mineral}}
{{Other uses}}
{{Use American English|date=December 2021}}<!-- Appears to be current dialect in use ("color" not "colour", etc.) -->
{{Infobox mineral
| name        = Muscovite
| category    = [[Phyllosilicate]] [[minerals]], [[mica]] [[Mineral group|group]]
| image       = Muscovite-Albite-122887.jpg
| imagesize   = 
| caption     = Muscovite with [[albite]] from [[Doce River|Doce]] valley, [[Minas Gerais]], Brazil (dimensions: 6 × 5.3 × 3.9 cm)
| formula     = KAl<sub>2</sub>(AlSi<sub>3</sub>O<sub>10</sub>)(F,OH)<sub>2</sub>
| IMAsymbol   = Ms<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>
| molweight   = 
| strunz      = 9.EC.15 
| dana        = 71.02.02a.01
| system      = [[Monoclinic]]
| class       = Prismatic (2/m) <br/><small>(same [[H-M symbol]])</small>
| symmetry    = ''C2/c'' 
| unit cell   = a = 5.199&nbsp;[[Ångstrom|Å]], b = 9.027&nbsp;Å, <br/>c = 20.106&nbsp;Å, β = 95.78°; Z&nbsp;=&nbsp;4
| color       = White, grey, silvery
| habit       = Massive to platy
| twinning    = Common on the [310], less common on the {001}
| cleavage    = Perfect on the {001}
| fracture    = Micaceous
| tenacity    = Elastic
| mohs        = 2–2.5 parallel to {001} <br/>4 right angle to {001}
| luster      = Vitreous, silky, pearly
| polish      = 
| refractive  = n<sub>α</sub> = 1.552–1.576 <br/>n<sub>β</sub> = 1.582–1.615 <br/>n<sub>γ</sub> = 1.587–1.618
| opticalprop = Biaxial (−)
| birefringence = δ = 0.035 – 0.042
| dispersion  = r > v weak
| pleochroism = Weak when colored
| fluorescence= None
| absorption  = 
| streak      = White
| gravity     = 2.76–3
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Transparent to translucent
| other       = 
| references  = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Muscovite Mineralienatlas]</ref><ref>[http://mindat.org/min-2815.html Muscovite mineral information and data Mindat]</ref><ref>[http://webmineral.com/data/Muscovite.shtml Muscovite Mineral Data Webmineral]</ref><ref>[http://rruff.geo.arizona.edu/doclib/hom/muscovite.pdf Handbook of Mineralogy]</ref>
}}

'''Muscovite''' (also known as '''common mica''', '''isinglass''', or '''potash mica'''<ref>[http://www.britannica.com/eb/article-9054407/muscovite Encyclopædia Britannica]</ref>) is a hydrated [[Silicate minerals#Phyllosilicates|phyllosilicate]] mineral of [[aluminium]] and [[potassium]] with formula KAl<sub>2</sub>(Al[[silicon|Si]]<sub>3</sub>[[oxygen|O]]<sub>10</sub>)([[fluorine|F]],O[[hydrogen|H]])<sub>2</sub>, or ([[potassium fluoride|KF]])<sub>2</sub>([[aluminate|Al<sub>2</sub>O<sub>3</sub>]])<sub>3</sub>([[silicate|SiO<sub>2</sub>]])<sub>6</sub>([[hydrate|H<sub>2</sub>O]]). It has a highly perfect [[basal cleavage]] yielding remarkably thin laminae (sheets) which are often highly [[Elasticity (physics)|elastic]]. Sheets of muscovite {{convert|5|x|3|m|ft|sp=us}} have been found in [[Nellore]], [[India]].<ref>{{cite journal| url = http://www.minsocam.org/ammin/AM66/AM66_885.pdf| journal = American Mineralogist| volume = 66| pages = 885–907| year= 1981| title= The largest crystals| author = P. C. Rickwood}}</ref>

Muscovite has a [[Mohs hardness]] of 2–2.25 parallel to the [001] face, 4 perpendicular to the [001] and a [[specific gravity]] of 2.76–3. It can be colorless or tinted through grays, violet or red, and can be transparent or translucent. It is [[anisotropic]] and has high [[birefringence]]. Its crystal system is [[monoclinic]]. The green, [[chromium]]-rich variety is called [[fuchsite]]; [[mariposite]] is also a chromium-rich type of muscovite.

Muscovite is the most common [[mica]], found in [[granite]]s, [[pegmatite]]s, [[gneiss]]es, and [[schist]]s, and as a contact [[metamorphic rock]] or as a secondary [[mineral]] resulting from the alteration of [[topaz]], [[feldspar]], [[kyanite]], etc. It is characteristic of [[peraluminous rock]], in which the content of aluminum is relatively high.<ref>Blatt, Harvey and Robert J. Tracy, ''Petrology,'' Freeman, 2nd ed., 1995, p. 516 {{ISBN|0-7167-2438-3}}</ref> In pegmatites, it is often found in immense sheets that are commercially valuable. Muscovite is in demand for the manufacture of [[fireproofing]] and insulating materials and to some extent as a [[lubricant]].