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Muscovite Facts

Muscovite Facts
Muscovite is the most common of the Mica Group minerals. It can be found in igneous, metamorphic and sedimentary rocks such as pegmatites, gneisses, schists and most common in granitic rocks where it is found in large crystals. These crystals are referred to as "books" since they can be split into paper-thin sheets. It is easily identified due to its smooth cleavage which allows it to be split into nearly colorless, transparent, thin, flexible sheets with a pearly shimmer. Most have a rose, yellow or green color tint.
Interesting Muscovite Facts:
Muscovite is not resistant to chemical weathering. It can quickly transform into clay minerals as tiny flakes can sometime survive long enough to be incorporated into immature sedimentary rocks and sediments.
It can form during regional metamorphism of argillaceous rocks. Clay minerals transform into tiny grains of mica during the heat and pressure of metamorphism and enlarge as metamorphism progresses.
When the mineral takes on an apple green color, it is known as "fuschite". This occurs when chromium substitutes for aluminum in muscovite. When the rock has a distinct green color, the name "verdite" is used.
In the 1700s, Pegmatites were mined in Russia. They split the mineral into transparent sheets and used them as a cheaper alternative to glass in windows. It was called "muscovy glass".
Manufacturers use ground mica to make rubber. In tires and roofing, it acts as an anti sticking agent.
Dry-ground mica is also used as an anti-stick agent on asphalt shingles. It stands up well to weather and does not absorb the asphalt.
It is used as an additive to drilling mud which assists in sealing porous sections of the drill hole to reduce circulation loss.
The mineral is added to paint as a pigment extender which reduces chalking and brightens the tone of colored pigments.
In joint compound, it serves as a filler which makes it easier to work with and reduces cracking in the finished product.
It is added to plastic to serve as an agent to absorb vibration and sound.
Due to the mineral's pearlescent luster, it is also commonly used as "glitter" in cosmetics, such as lipstick, eye shadow and nail polish.
Sheet mica is used to electronic devices such as medical electronics, radar systems and oxygen breathing equipment.
In 2011, the United States produced about 50,000. China produced 700,000 tons, being the largest producer and largest consumer.
Due to prices being high for this material, substitutes are being used. Creation of synthetic micas are created in laboratories to use as substitutes, such as polyester, nylon and fiberglass.
When sheets of mica have inclusions of hematite, rutile or magnetite, they are often sold at a reduced price to use for low-quality windows for ovens and furnaces.


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