Muscovite


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muscovite:

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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Muscovite

 

(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.

muscovite

[′məs·kə‚vīt]
(mineralogy)
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.

Muscovite

1. a native or inhabitant of Moscow
2. an archaic word for Russian
References in periodicals archive ?
Their mineral assemblage is quartz + graphite + muscovite + chlorite + plagioclase (Albite) [+ or -] biotite.
The rocks intersected consisted of highly altered muscovite and silica schists.
Muscovite ideas and practices turned out to be eclectic, drawing from the earlier traditions of Rus', the influence of Qipchaq overlords, and eventually an intensive but selective adaptation and reinterpretation of Byzantine models (see for example Ostrowski 1998; Uspenskii 1998).
Monday's deadly attacks shocked a country that had grown accustomed to such violence being confined to a restive southern corner -- and marked the return of terrorism to the everyday lives of Muscovites following a six-year break.
The purpose of this letter was to secure Muscovite military assistance by appealing to the tsar's religious feelings.
Here Rosefielde argues that Putin's Russia is closer to its Muscovite roots than to a Western market economy.
Unlike the earlier Muscovite renaissance, which was prompted principally by the presence of Italian--mainly Lombard--craftsmen, in the 18th century architects were recruited from across the continent, confirming the international nature of the baroque style.
Pour limiter la petrogenese et le passe thermique de la pegmatite, on a preleve des echantillons de tantalite, de molybdenite et de muscovite en vue de datations U-Pb, Re-Os et [sup.
The Muscovite audience was reportedly mystified; more progressive Americans, no doubt, will respond differently.
Mr Smolenski, a Muscovite, was formerly a director of Bank OVK.
Here Tarasov expertly describes the rise of Old Belief and the tear in the hitherto seamless cloth of Muscovite society, and how religious sensibilities reflecting this are manifested in icons.
In addition, samples taken from the property indicate the presence of muscovite and silica concentrates.