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see micamica
, general term for a large group of minerals, hydrous silicates of aluminum and potassium, often containing magnesium, ferrous iron, ferric iron, sodium, and lithium and more rarely containing barium, chromium, and fluorine.
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(from Muscovy, the old name for Russia, from where large sheets of the mineral were exported to the West under the name of Muscovy glass), a mineral from the mica group with the empirical formula KA12[[AlSi3O10] • (OH)2. Crystals are tabular and in the monoclinic system. Basal cleavage is extremely perfect. Muscovite is easily split into very thin sheets. This is caused by its crystalline structure, which is composed of three-layer packets of two sheets of aluminum-oxygen and silicon-oxygen tetrahedrons connected through a layer of octahedrons, in the center of which are located aluminum ions, each surrounded by four oxygen ions and two OH groups. One-third of the octahedrons are not filled with aluminum ions. The packets are interconnected through potassium ions.

Muscovite has a hardness on Mohs’ scale of 2.5–3; its density is 2,760–3,100 kg/m3. The mineral is usually colorless; sometimes, light brown, pale green, or other colors. Its luster is vitreous; on the cleavage planes the luster is pearly or silvery. Muscovite is sometimes found as cryptocrystalline masses with a silky luster. In this form it is called sericite.

Muscovite is a widespread mineral and is found as a component of magmagene rocks and also metamorphic rocks such as granites, granite pegmatites, syenites, greisens, crystalline schists, and gneisses. Of industrial significance is the muscovite recovered from pegmatite veins, where the mineral occurs as large crystals or as accumulations measuring 1–2 m thick.

Muscovite is most frequently used in electrical insulation. In industry, it is used in the form of sheet mica (for insulators, condensers, and telephones), mica powder (for roofing paper, mica board, and fireproof paints), and mica products (for electrical insulating gaskets in electric instruments). In the USSR, muscovite deposits are found on the Kola Peninsula and in Eastern Siberia near Mama and Kanska. Muscovite is also found in India, the Malagasy Republic, Canada, the United States, and Brazil.


KAl2(AlSi3)O10(OH)2 One of the mica group of minerals, occurring in some granites and abundant in pegmatites; it is colorless, whitish, or pale brown, and the crystals are tabular sheets with prominent base and hexagonal or rhomboid outline; hardness is 2-2.5 on Mohs scale, and specific gravity is 2.7-3.1. Also known as common mica; mirror stone; moscovite; Muscovy glass; potash mica; white mica.


1. a native or inhabitant of Moscow
2. an archaic word for Russian
References in periodicals archive ?
We're continuing to penetrate the cosmetic and personal care product markets with our wet-ground muscovite mica.
In all mesh sizes, muscovite mica maintains a plate-like structure with high thickness-to-diameter ratios of 1:25.
Company also offers muscovite micas that are said to have outstanding aspect ratio, purity, and whiteness properties.
5% from the comparable period in 1999, in part due to the costs associated with the start-up of the Corporation's muscovite mica and calcium aluminate facilities.
Lastly, we are still dealing with the start-up costs associated with both our calcium aluminate and muscovite mica facilities.
The only two negatives in the quarter were the start-up of the Corporation's muscovite mica operation in Spruce Pine, NC and its calcium aluminate facility in Cleveland, Ohio.
Wet-ground muscovite mica consists of tiny, extremely thin flakes of a potassium /aluminum silicate crystal with traces of other elements.
Micawhite and Polymica, grades of white muscovite mica are available both treated and untreated.
Operating margins benefited from higher volumes, improved recoveries and increased operating efficiencies, offset in part by the costs associated with the start-up of its reconstructed muscovite mica facility in Spruce Pine, NC.
has six new particle-size distributions of its surface-modified HiMod muscovite micas.