Muscovite Facts
Muscovite is one of the two common forms of the mineral mica, the other being biotite. Muscovite mica commonly occurs as small crystals in some types of igneous, sedimentary and metamorphic rocks, but at other times it forms larger crystals, which come in the form of layered sheets. These sheets can usually be separated with each individual piece forming a translucent and flexible layer.
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Chemical Composition
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Muscovite is a form of mica that contains a common silicate mineral that contains potassium, aluminum and fluoride along with the silicon-oxygen mixture that puts the chemical composition under the sub-grouping of a silicate. On rare occasions muscovite contains chromium, which can give the crystals a greenish tint.
Distribution
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Mica is a small, shiny mineral that can be seen in many common rocks such as schists, gneisses, granite and some forms of sandstone. The larger crystals of muscovite mica often occur when the mineral comes in association with pegmatite. When this occurs mica is then mined and prepared for commercial use.
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Description
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Muscovite is most commonly found as small specks of shiny material in a rock such as granite. The large crystals are less common, but are quite unique in the mineral world, because of the thin, flexible layers than they form. Also of interest is the way each layer can be separated with the blade of a knife. The crystals can be silver, white, yellow or green and range in opacity from a milky white to translucent. The hardness of this mica ranges from 2 to 2.5 on the mineral hardness scale.
Indicator of Precious Crystals
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Muscovite mica can be an indicator of other valuable crystals that sometimes come in association with the common mineral. These valuable minerals include tourmaline, topaz, beryl and almandine. Often muscovite is found in conjunction with quartz crystals, which are very common, yet, sometimes quite distinctive and beautiful. On rare occasions, muscovite mica forms a rare five-pointed star, called Star Muscovite.
Commercial Uses
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Historically, muscovite mica was first used in window panes, but in more modern times it has been used where there is need for a clear or translucent sheet of mineral substance that is heat resistant and flexible. Muscovite mica fits this bill perfectly and as a result it was a common part of toasters and furnace windows. Today mica is most commonly ground up and used as a material in house paint. It can also be found in some electrical components because of its good insulating qualities.
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