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About mica
Mica-aluminum silicate minerals.

http://www.answers.com/topic/mica

Anyone of a group of hydrous aluminum silicate minerals with platy morphology and perfect basal (micaceous) cleavage. The most common micas are muscovite [KAl2(AlSi3O10)(OH)2], paragonite [NaAl2(AlSi3O10)(OH)2], phlogopite [K(Mg,Fe)3 (AlSi3O10)(OH)2], biotite [K(Fe,Mg)3(AlSi3O10)(OH)2], and lepidolite [K(Li,Al)2.5-3.0(Al1.0-0.5Si3.0-3.5O10)(OH)2]. Calcium (Ca), barium (Ba), rubidium (Rb), and cesium (Cs) can substitute for sodium (Na) and potassium (K); manganese (Mn), chromium (Cr), and titanium (Ti) for magnesium (Mg), iron (Fe), and lithium (Li); and fluorine (F) for hydroxyl (OH). The three major species, muscovite, biotite, and phlogopite, are widely distributed rock-forming minerals, occurring as essential constituents in a variety of igneous, metamorphic, and sedimentary rocks and in many mineral deposits.

Mica is commonly found as small flakes or lamellar plates without a crystal outline. Muscovite and biotite sometimes occur in thick books, tabular prisms with a hexagonal outline that can be up to several feet across. The prominent basal cleavage is a consequence of the layered crystal structure. Thin cleavage sheets of micas, particularly muscovite and phlogopite, are flexible, elastic, tough, and translucent to transparent (isinglass). They have low electrical and thermal conductivity and high dielectric strength.

Micas have Mohs hardnesses of 2–3 and specific gravities of 2.8–3.2. Upon heating in a closed tube, they evolve water. They have a vitreous-to-pearly luster. Muscovite is colorless to pale shades of brown, green, or gray. Paragonite is colorless to pale yellow. Phlogopite is pale yellow to brown. Biotite is dark green, brown, or black. Lepidolite is most often pale lilac, but it can also be colorless, pale yellow, or pale gray. See also Biotite; Hardness scales.

Commercial mica is of two main types: sheet, and scrap or flake. Sheet muscovite, mostly from pegmatites, is used as a dielectric in capacitors and vacuum tubes in electronic equipment. Lower-quality muscovite is used as an insulator in home electrical products such as hot plates, toasters, and irons. Scrap and flake mica is ground for use in coatings on roofing materials and waterproof fabrics, and in paint, wallpaper, joint cement, plastics, cosmetics, well drilling products, and a variety of agricultural products. See also Capacitor; Electric insulator; Silicate minerals.




  • Phlogopite
    more
    details
  • Crystallography
    details
  • MICA
    the Maryland Institute College of Art
    details
  • Mica Lighting .
    http://www.micalamps.com/
    details
  • Phyllosilicate mineral of aluminium and potassium
    http://en.wikipedia.org/wiki/Muscovite
    details
  • Silver mica
    http://www.patentstorm.us/patents/4025829.html
    details
  • MICA-Mineral Information Institute
    http://www.google.com/
    details
  • Biotite
    http://www.britannica.com/EBchecked/topic/66240/biotite
    details
  • Muscovite.
    http://www.mineralszone.com/minerals
    details
  • Mica-aluminum silicate minerals.
    http://www.answers.com/topic/mica
    details
  • Mica Shields
    details
  • Mica Histori & General Information.
    details
  • Muscovite.
    http://itc.gsw.edu/faculty/bcarter/physgeol/min/musc.htm
    details
  • Britannica about mica.
    Asian deposits, chemical etching, compressibility...
    details
  • Micanite.
    details
  • Mineral Muscovite.
    details
  • The Mica Group of minerals
    details
  • Mica - Explanation and use.
    details
  • Mica grouping (chemical composition)
    details
  • Molding micaceous laminate
    details
  • Mica insulation
    details
  • New electric insulating materials
    details
  • SOGM - SMOG
    details
  • Mica and ecology
    details
  • English version (page about mica)
    details
  • Chemical composition of mica
    details
  • Molding micanite, Federal Standard 6122-75
    details
  • Key trends in mica consumption. Application areas
    details
  • Mica types, grades and application areas
    details
  • If microwave oven's strip burned out
    details
  • Universal insulating materials
    details
  • Mica-bearing materials list
    details
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