Muscovite
Muscovite from a pegmatite outcrop along the Patapsco River in Baltimore County, Maryland.
General
Category	Mineral Species
Chemical formula	KAl2(AlSi3O10)(F,OH)2
Identification
Molecular Weight	398.71 gm
Color	White, grey, silvery
Crystal habit	massive to platy Crystaline
Crystal system	Monoclinic - Prismatic
Twinning	common on the [310] less common on the {001}
Cleavage	Perfect on the {001}
Fracture	Micaeous
Tenacity	Elastic
Mohs Scale hardness	2-2.5, 4
Luster	Vitreous
Refractive index	nα = 1.552 - 1.576 nβ = 1.582 - 1.615 nγ = 1.587 - 1.618
Optical Properties	Biaxial
Birefringence	δ = 0.035 - 0.042
Dispersion	r > v weak
Pleochroism	weak when colored
Ultraviolet fluorescence	None
Streak	White
Specific gravity	2.76 - 3
Density	2.83 g/cm3
Melting point	approximately 1320°C
Diaphaneity	transparent or translucent
References	[1][2]

Muscovite (also known as Common mica, Isinglass, or Potash mica^[3]) is a phyllosilicate mineral of aluminium and potassium with formula: KAl₂(AlSi₃O₁₀)(F,OH)₂. 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.^[4] Muscovy (Moscow principality (княжество Московское) to Grand Duchy of Moscow (Великое Княжество Московское) to Russian Tsardom (Царство Русское)) is a traditional Western name for the Russian state that existed from the 14th century to the late 17th century. ... Image File history File links No higher resolution available. ... This article or section does not cite its references or sources. ... The Patapsco is a river in central Maryland which flows into the Chesapeake Bay in Baltimore, Maryland. ... For other uses of Baltimore, see Baltimore (disambiguation). ... Official language(s) None (English, de facto) Capital Annapolis Largest city Baltimore Largest metro area Baltimore-Washington Metropolitan Area Area  Ranked 42nd  - Total 12,407 sq mi (32,133 km²)  - Width 101 miles (145 km)  - Length 249 miles (400 km)  - % water 21  - Latitude 37° 53′ N to 39° 43′ N... For other uses, see Mineral (disambiguation). ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... It has been suggested that twin boundary be merged into this article or section. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For other uses, see Fracture (disambiguation). ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Dispersion of a light beam in a prism. ... Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized Cadmium selenide (CdSe) quantum dots. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... For other uses, see Density (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... Rock with mica Mica sheet Mica flakes The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. ... Potash Potash (or carbonate of potash) is an impure form of potassium carbonate (K2CO3) mixed with other potassium salts. ... The silicate minerals make up the largest and most important class of rock-forming minerals. ... For other uses, see Mineral (disambiguation). ... Aluminum redirects here. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ...

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 grays, browns, greens, yellows, or (rarely) violet or red, and can be transparent or translucent. The green chromium rich variety is called fuchsite. Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Gray or grey is a color seen commonly in nature. ... For other uses, see Brown (disambiguation). ... For other uses, see Green (disambiguation). ... A yellow Tulip. ... Violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometres (this is a spectral color). ... For other uses, see Red (disambiguation). ... General Name, symbol, number chromium, Cr, 24 Chemical series transition metals Group, period, block 6, 4, d Appearance silvery metallic Standard atomic weight 51. ...

Muscovite layer

Fuchsite from Slovakia

Muscovite is the most common mica, found in granites, pegmatites, gneisses and 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. Muscovite layer Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Muscovite layer Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Mineraly. ... Image File history File links Mineraly. ... For other uses, see granite (disambiguation). ... This article or section does not cite its references or sources. ... Gneiss Gneiss (IPA: ) is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks, which most commonly forms on ancient seabeds. ... Schist The schists form a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. ... Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... For other uses, see Mineral (disambiguation). ... This article is about the mineral or gemstone. ... This article does not cite any references or sources. ... Kyanite, whose name derives from the Greek, kyanos, meaning blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. ... Fireproofing, a passive fire protection measure, subject to bounding, refers to the act of making materials or structures more resistant to fire, or to those materials themselves. ... A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ...

The name of muscovite comes from Muscovy-glass, a name formerly used for the mineral because of its use in Russia for windows. It is anisotropic, and has quite a high birefringence. Its crystal system is monoclinic. For other uses, see Window (disambiguation). ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ...

See also

• List of minerals

Gem animals. ...

References

• Mineral Handbook
• Mindat
• Webmineral

1. ^ http://www.mindat.org/min-2815.html
2. ^ http://www.webmineral.com/data/Muscovite.shtml
3. ^ Encyclopædia Britannica
4. ^ The Complete Encyclopedia of Minerals by P. Korbel and M. Novak

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