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 ?
The rocks correspond to actinolite schists and chlorite schists (Figure 3a and 3b) with mineral assemblages as follows: actinolite + chlorite + quartz + plagioclase (albite) + epidote minerals [+ or -] muscovite [+ or -] calcite.
According to the Moscow Times, that idea finds support among 23 percent of the population and 43 percent of Muscovites, even though Moscow has always been a diverse, multiethnic city.
Sergei Kapkov, the head of Moscow's culture department, said both Muscovites and city guests will "like very much" the festive events, which, he pledged, will be "very interesting.
Dubnow (1916:242-261) actually believed that the experience of the Judaisers had "struck terror to the hearts of the pious Muscovites," traumatising them to the extent that they could not tolerate the presence of actual Jews.
The new Muscovite cultural history; a collection in honor of Daniel B.
Grieving Muscovites added to heaps of flowers and placed photographs of the dead under memorial plaques at the stations.
Muscovites continue to exchange horror stories of being stuck in traffic for up to seven hours that day, as nearly 3,000 road accidents were reported around the capital.
However, in January 1668, Briukhovets'kyi, sensing the growing animosity towards the Muscovites among his subjects, was inspired by Doroshenko, his former rival and now ally, and rebelled against the tsar, wiping out some Muscovite garrisons and besieging others.
The city also has the second worst-dressed metropolitans in Europe after Muscovites.
Lord knows what the tough Muscovites, who've lived through terrible hardships, made of the multimillionaire Englishman blubbing over a fluffed kick.
For decades his cruel visage glowered down upon Muscovites and visitors from a giant 16-ton statue that stood in Moscow's Lubyanka Square, outside the KGB headquarters.
According to Hessler, these cycles of crisis and recovery inculcated in both the state and consumers habits that eventually developed into a Soviet "exchange culture," based on, among other things, bureaucratism, solicitude for urban consumers, especially Muscovites, a neglect of the rural market, and a tolerance among citizens for breaking the law in the interests of survival.