What is Muscovite?
Muscovite, also called common mica, isinglass and potash mica, is a chemical compound consisting of hydrous silicates of aluminum and potassium. It is a commercially valuable material used in fireproofing and electric insulation. Muscovite is found in immense sheets in several locations around the globe, mainly in sedimentary and metamorphic rocks, granites, schists, gneisses and pegmatities. Muscovite was first used in Old Russia for aesthetic purposes as a window glass because of its transparent crystals. Muscovite sheets were also used in making kitchen oven windows before synthetic materials superseded them.
Occurrence
Muscovite deposits are found in many countries, however, not every locality offers a high yield production. The largest deposits of muscovite are found in India, Pakistan, Brazil and the Commonwealth of Independent States. The United States does not produce a substantial amount of muscovite, but it is a leading manufacturer of high quality scrap mica. The major scrap mica production facilities in the United States are situated in Georgia, Connecticut, New Mexico, South Dakota, and North and South Carolina.
Muscovite deposits
Muscovites are usually found in large sheets extending over several feet, called books. Muscovite resembles granite and granite pegmatites in its characteristics. Serecite, a variety of muscovite, is found in some schistose rocks as a fibrous aggregate with subtle scales and a silky luster. Quality muscovite deposits are normally seen in pegmatites all over the world. Illite is another variety of muscovite which is a constituent of recent soils, shales and sediments.
Chemical Structure
Muscovite has a perfect basal cleavage structure consisting of aluminum silicate sheets held fast by layers of potassium ion. It is the potassium ions which give rise to the highly-perfect cleavage of muscovite. The thin layers of aluminum silicate sheets are often very elastic, thus the cleavage sheets are very durable.
Features
Muscovite is better known to chemists as potassium aluminum silicate hydroxide fluoride. It has been classified under the silicates class and phylosilicatessubclass. Muscovite can be white or tinted silver, yellow, gras, green, brown, or seldomly red or violet. The chromium-rich, green colored variety is known as fuchsite. Muscovite crystals are either transparent or translucent, and its luster is vitreous to pearly. It has a hardness of 2 to 2.5 and a specific gravity of approximately 2.8 (average).
Uses
Muscovite is valuable for its dielectric and heat resistant properties. The main application of muscovite is as an insulating material in electrical equipment. It is also used in cosmetics because it has a shiny appearance, as a fireproofing agent, and as a lubricant to some extent.
Tags: aluminum silicate, also used, aluminum silicate sheets, muscovite found, scrap mica, silicate sheets