Muscovite 21062 224436732 2008-07-08T20:57:42Z TDogg310 329397 {{Otheruses2|Muscovite}} {{Infobox mineral | name = Muscovite | category = [[Mineral]] Species | boxwidth = | boxbgcolor = | image = Muscovite2.jpg | imagesize = 200px | caption = Muscovite from a [[pegmatite]] outcrop along the [[Patapsco River]] in [[Baltimore County, Maryland|Baltimore County]], [[Maryland]]. | formula = KAl<sub>2</sub>(AlSi<sub>3</sub>O<sub>10</sub>)(F,OH)<sub>2</sub> | molweight = 398.71 gm | color = White, grey, silvery | habit = massive to platy Crystaline | system = Monoclinic - Prismatic | twinning = common on the [310] less common on the {001} | cleavage = Perfect on the {001} | fracture = Micaeous | tenacity = Elastic | mohs = 2-2.5, 4 | luster = Vitreous | polish = | refractive = n<sub>α</sub> = 1.552 - 1.576 n<sub>β</sub> = 1.582 - 1.615 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 = 2.83 g/cm<sub>3</sub> | melt = approximately 1320°C | fusibility = | diagnostic = | solubility = | diaphaneity = transparent or translucent | other = | references =<ref>[http://www.mindat.org/min-2815.html Muscovite: Muscovite mineral information and data<!-- Bot generated title -->]</ref><ref>[http://www.webmineral.com/data/Muscovite.shtml Muscovite Mineral Data<!-- Bot generated title -->]</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 [[Silicate minerals|phyllosilicate]] [[mineral]] of [[aluminium]] and [[potassium]] with formula: [[potassium|K]][[aluminum|Al]]<sub>2</sub>(Al[[silicon|Si]]<sub>3</sub>[[oxygen|O]]<sub>10</sub>)([[fluorine|F]],O[[hydrogen|H]])<sub>2</sub>. It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets), which are often highly elastic. Sheets of muscovite 5 metres by 3 metres have been found in Nellore, India.<ref>''The Complete Encyclopedia of Minerals'' by P. Korbel and M. Novak</ref> Muscovite melts at approximately 1320°C, 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 [[gray (color)|grays]], [[brown|browns]], [[green|greens]], [[yellow|yellows]], or (rarely) [[violet (color)|violet]] or [[red]], and can be transparent or translucent. The green, [[chromium]]-rich variety is called '''fuchsite'''. Muscovite is the most common mica, found in [[granite|granites]], [[pegmatite|pegmatites]], [[gneiss|gneisses]] and [[schist|schists]], and as a contact [[metamorphic rock]] or as a secondary [[mineral]] resulting from the alteration of [[topaz]], [[feldspar]], [[kyanite]], etc. 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]]. The name of muscovite comes from Muscovy-glass, a name formerly used for the mineral because of its use in [[Russia]] for [[window|windows]]. It is [[anisotropic]], and has high [[birefringence]]. Its crystal system is [[monoclinic]]. == See also == * [[List of minerals]] == References == *[http://rruff.geo.arizona.edu/doclib/hom/muscovite.pdf Mineral Handbook] *[http://www.mindat.org/min-2815.html Mindat] *[http://webmineral.com/data/Muscovite.shtml Webmineral] <references/> {{Commonscat|Muscovite}} {{mineral-stub}} [[Category: Potassium minerals]] [[Category: Aluminium minerals]] [[Category: Hydroxide minerals]] [[Category: Phyllosilicates]] [[Category: Mica group]] [[ca:Moscovita]] [[cs:Muskovit]] [[de:Muskovit]] [[eo:Muskovito]] [[es:Moscovita]] [[fr:Muscovite]] [[gl:Moscovita]] [[it:Muscovite]] [[he:מוסקוביט]] [[hu:Muszkovit]] [[nl:Muscoviet]] [[ja:白雲母]] [[nds:Muskovit]] [[pl:Muskowit]] [[pt:Moscovita]] [[ru:Серицит]] [[sk:Muskovit]] [[fi:Muskoviitti]] [[tr:Muskovit]]