Muscovite Information
Muscovite is a widely distributed mineral that belongs to the mica group and comes in a variety of colors. Used since the Middle Ages, muscovite is a commercially viable mineral with applications ranging from industrial to cosmetic.
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Features
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Muscovite is a transparent, shiny and soft mineral rating only 2 to 2.5 on the relative scale of hardness, the Moh's scale, on which diamond is a 10. It has a pearly luster and can be found as one of many colors, including light gray (silver), rose, brown, yellow, light green or the most common color, white.
Muscovite's crystal form is monoclinic, which means it forms three axles with one not at right angles to the rest. It has perfect cleavage, breaks into thin sheets and forms a hexagonal outline.
Other features include its inability to conduct electricity and its ability to resist heat. These features are part of what makes it commercially viable.
Chemistry
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Muscovite's chemical formula, in general, is KAl2(AlSi3O10)(F,OH)2. This means that it is made of aluminum, potassium, silicon, oxygen and fluoride, and it is classified as a potassium aluminum silicate.
Muscovite is also classified as a light silicate (or nonferromagnesian silicate), a mineral that contains more calcium, potassium and sodium than magnesium and iron. This is in contrast to dark silicates (or ferromagnesian silicates), which are high in magnesium and iron and are usually low in silicates when compared to light silicates.
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Formation
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Muscovite forms in pegmatites and other igneous rocks that crystallize deep underground. It can be found in detrial (nonchemically formed) sedimentary rocks and metamorphic rocks.
In igneous rocks, muscovite often forms in granite, aplite, granite pegmatites and granodiorite. In metamorphic rocks, it forms in gneisses, slate, quartzite, phyllite, schists and homfel. In sedimentary rocks, it is often found in siliclastic sedimentary rocks and arkosic sandstone.
History
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Thought to have been introduced to Russians from the Tartars, muscovite was used in Russia as a kind of glass and was called Muscovy-glass (a use begun earlier in India). This led scientist James Dwight Dana to name it "muscovite" in 1850.
Function
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Muscovite is used in such items as electrical insulation, capacitors, transistors, filler (in paint, wallboard cement and plastic), wallpaper coating, lubricant in oils, glitter and makeup such as eyeshadow, nail polish and lipstick.
Sources
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Muscovite can be found in Russia (Mursinka), Norway (Bamble, Kragerö and Kammerfors), Canada (Ontario), South America (Brazil), India (Andhra Pradesh) and the United States.
In the United States, muscovite is in Virginia, South Dakota, New Mexico, Pennsylvania, Maine, South Carolina, Connecticut and North Carolina.
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References
Resources
- Photo Credit world map image by Attila Toro from Fotolia.com
