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Information about Mica

Mica may refer to: MICA can refer to:

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Rock with mica
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Mica sheet
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Mica flakes
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic with a tendency towards pseudo-hexagonal crystals and are similar in chemical composition. The highly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms.

The word "mica" is thought to be derived from the Latin word micare, for glitteren, in reference to the brilliant appearance of this mineral (especially when in small scales).

Mica classification

Chemically micas can be given the general formula:[1]
X2Y4-6Z8O20(OH,F)4
in which X is K, Na, or Ca or less commonly Ba, Rb, or Cs
Y is Al, Mg or Fe or less commonly Mn, Cr, Ti, Li, etc
Z is chiefly Si or Al but also may include Fe3+ or Ti
Structurally the micas can be classed as di-octahedral (Y = 4) and tri-octahedral (Y = 6). Also if the X ion is K or Na the mica is a common mica whereas if the X ion is Ca the mica is classed as a brittle mica.

Tri-octahedral micas

Common micas: Brittle micas

Interlayer deficient micas

Very fine grained micas with typically more variation in ion and water content are informally termed clay micas and include:
  • hydro-muscovite with H3O+ along with K in the X site.
  • Illite with a K deficiency in the X site and correspondingly more Si in the Z site.
  • Phengite with Mg or Fe2+ substituting for Al in the Y site and a corresponding increase in Si in the Z site.

Occurrence

In 2005, India has the largest deposits of mica in world. China was the top producer of mica with almost one-third global share closely followed by the USA, South Korea and Canada, reports the British Geological Survey.

Mica is widely distributed and occur in igneous, metamorphic and sedimentary regimes. Large crystals of mica used for various applications are typically mined from granitic pegmatites.

Until the 19th century, large crystals of mica were quite rare and expensive as a result of the limited supply in Europe. However, its price dramatically dropped when large reserves were found and mined in Africa and South America since early 19th century.

Scrap and flake mica is produced all over the world. The flake mica comes from several sources: the metamorphic rock called schist as a by-product of processing feldspar and kaolin resources, from placer deposits, and from pegmatites. Sheet mica is considerably less abundant than flake and scrap mica. Sheet mica is occasionally recovered from mining scrap and flake mica. The most important sources of sheet mica are the pegmatite deposits.

Properties and uses

Mica has a high dielectric strength and excellent chemical stability, making it a favored material for manufacturing capacitors for radio frequency applications. It has also been used as an insulator in high voltage electrical equipment. It is also birefringent and is commonly used to make quarter and half wave plates.

Because mica is resistant to heat it is used instead of glass in windows for stoves and kerosene heaters. It is also used to separate electrical conductors in cables that are designed to have a fire-resistance rating in order to provide circuit integrity. The idea is to keep the metal conductors from fusing in order to prevent a short-circuit so that the cables remain operational during a fire, which can be important for such things as emergency lighting.

Illites or clay micas have a low cation exchange capacity for 2:1 clays. K+ ions between layers of mica prevent swelling by blocking water molecules.

Aventurine is a variety of quartz with mica inclusions used as a gemstone.

Pressed Mica sheets are often used in place of glass in greenhouses.

Muscovite mica is the most common substrate for sample preparation for the Atomic force microscope.

Some brands of toothpaste include powdered white mica. This acts as a mild abrasive to aid polishing of the tooth surface, and also adds a cosmetically-pleasing glittery shimmer to the paste.

Mica in ancient times

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Hand carved from mica from the Hopewell culture
Human use of mica dates back to pre-historic times, and mica was known to ancient Egyptian, Greek and Roman civilizations, Chinese civilization, as well as the Aztec civilization of the New World.

The earliest use of mica has been found in cave paintings created during the Upper Paleolithic period (40,000 BC to 10,000 BC), The first colors were red, iron oxide (hematite, a form of red ochre) and black (manganese dioxide), though black from juniper or pine carbons has also been discovered. White from kaolin or mica was used occasionally.

A few kilometeres northeast of Mexico City stands the ancient site of Teotihuacan. The most striking visual and striking structure of Teotihuacan is the towering pyramid of the sun. The pyramid contained considerable locally mined mica in layers up to one foot thick.[2]

Through out the ages, fine powders of mica have been used for various purposes, including decorative purposes. The coloured Gulal and Abeer used by Hindus of north India during holi festival contain fine small crystals of mica. The majestic Padmanabhapuram palace, Padmanabhapuram, 65 km from Trivandrum, India, has coloured mica windows.

The medieval Chinese mechanical engineer, horologist, pharmacologist, and statesman Su Song (1020-1101 AD) of the Song Dynasty outlined in his book Ben Cao Tu Jing the medicinal properties and uses of the then every known type of mica (which was 8 in all, refer to article on mineralogy).

References

1. ^ Deer, W. A., R. A. Howie and J. Zussman (1966) An Introduction to the Rock Forming Minerals, Longman, ISBN 0-582-44210-9
2. ^ Garrett G. Fagan, ed., Archaeological Fantasies: How Pseudoarchaeology Misrepresents the Past and Misleads the Public, p. 102, ISBN 0415305934
Micah (מִיכָה, Standard Hebrew Miḫa, Tiberian Hebrew Mîḵāh) is the name of several people in the Hebrew Bible (Old Testament), and means who is like God, possibly in the sense of unique''.
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Tanakh
Torah | Nevi'im | Ketuvim
Books of Nevi'im
First Prophets
1. Joshua
2. Judges
3. Samuel
4. Kings
Later Prophets
5. Isaiah
6. Jeremiah
7.
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The word mew can refer to:
  • Mews, a stable for horses.
  • Meow or Miaow, the noise cats make.
  • An old word for seagull, or the noise they make.
  • In falconry, an aviary for hunting birds such as falcons, see mews.
  • Mew (Pokémon), a Legendary Pokémon.

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Mica

County Cluj County

Population (2002) 3,854

Geographical coordinates
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Component villages Mica
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Cluj (IPA: [kluʒ], Hungarian: Kolozs); is a county (judeţ) of Romania, in Transylvania, with the capital city at Cluj-Napoca.
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Motto

(each main institution has its own motto)
Anthem
Deşteaptă-te, române!


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Motto

(each main institution has its own motto)
Anthem
Deşteaptă-te, române!


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Motto

(each main institution has its own motto)
Anthem
Deşteaptă-te, române!


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Mica Paris (born Michelle Wallen on April 27 1969 in London, England) is an English singer. She began singing in church at an early age and then went on to become a session singer at the age of 15, for bands such as Hollywood Beyond and Shakatak.
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Maryland Institute College of Art (MICA) is an art university in Baltimore, Maryland. It was founded in 1826, making it the oldest accredited art college in the United States.
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For other uses, see Mika.


Mica Penniman (born 18 August 1983), known as Mika (IPA [ˈmikə
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The word Serbian might be:
  • an adjective, meaning:
  • "of Serbs" (Serbian tradition, Serbian religion)

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Croatian}}} 
Official status
Official language of:
Burgenland (Austria)
Caraşova in Caraş-Severin County (Romania)
 Croatia
Molise (Italy)
Vojvodina (Serbia)
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Montenegrin may refer to:
  • Something or someone from or relating to Montenegro
  • The Montenegrin language
  • The Montenegrin people

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Macedonian language (македонски јазик, makedonski jazik) is a language in the Eastern group of South Slavic languages and is the official language of the Republic of Macedonia.
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The terms Slovenian and Slovene refer to anything related to Slovenia and its inhabitants. Both terms have been used for a long time in English explanation .
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Singapore

This article is part of the series:
Politics of Singapore

Constitution
Legislative
  • President: Sellapan Ramanathan
  • Parliament
  • Constituencies

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Maryland Institute College of Art (MICA) is an art university in Baltimore, Maryland. It was founded in 1826, making it the oldest accredited art college in the United States.
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Mudra Institute of Communications Ahmedabad (MICA) is a leading academic institution that has been set up to develop professional Communications management skills in India. Established in 1991, it is located on the outskirts of the western Indian city of Ahmedabad.
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Function air-to-air missile
Manufacturer MBDA
Entered service 1996 (MICA RF) and 2000 (MICA IR)
General characteristics
Engine One SNPE solid-propellant rocket motor
Launch mass 112 kg
Length 3.
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University of California, Berkeley is a public research university located in Berkeley, California, United States. Commonly referred to as UC Berkeley, Berkeley and Cal
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Australian Mobile Intensive Care Ambulances are well-equipped ambulances staffed by highly trained paramedics dispatched to emergency situations where patients require a high level of care comparable to a hospital ICU.
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Cosmetics ( pronunciation: cosmetic   (help info ) ) are substances used to enhance or protect the appearance or odor of the human body.
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Mika can refer to:
  • Mika (singer) (born 1983), Lebanon-born singer based in London.
  • Mika Nakashima (born 1983), popular Japanese singer.
  • FC MIKA, Armenian football team
  • Mika Stadium

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silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. This definition is broad enough to include species such as hexafluorosilicate ("fluorosilicate"), [SiF6]2−
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A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties.
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Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types:
  • Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes.

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monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a parallelogram as base.
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CRYSTAL is a quantum chemistry ab initio program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can be used for single molecules.[1] It is written by V.R. Saunders, R.
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atom (Greek ἄτομος or átomos meaning "indivisible") is the smallest particle still characterizing a chemical element.
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