what is mica

Texas State Historical Association - The Handbook of Texas Online - Nacogdoches, Texas, United States, Amethyst Galleries' Mineral Gallery - The Mica Group of Minerals, mica - Student Encyclopedia (Ages 11 and up). Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible. Mica is an example of sheet silicate minerals that can be employed in a number of different applications. Omissions? Among the principal rock-forming minerals, micas are found in all three major rock varieties—igneous, sedimentary, and metamorphic. It has a specific chemical formula, and is crystalline in structure. Get a Britannica Premium subscription and gain access to exclusive content. The most common include: purple lepidolite, black biotite, brown phlogopite and clear muscovite. It is a type of phyllosilicate, exhibiting a two-dimensional sheet or layer structure. Mica is heat-resistant and does not conduct electricity.  There are 37 different mica minerals. Colours vary between the different minerals, from silver and white to pink and purple tones. Any of a group of hydrous aluminosilicate minerals with the general formula (K,Na,Ca) (Mg,Fe,Li,Al)2-3(Al,Si)4O10(OH,F)2that can be split easily into thin, partly transparent sheets. Each industry, although somewhat dependent on the other, produces different end products. For example, most muscovites contain sodium substituting for some potassium, and diverse varieties have chromium or vanadium or a combination of both replacing part of the aluminum; furthermore, the Si:Al ratio may range from the indicated 3:1 up to about 7:1. Crosscuts and raises are developed to follow promising exposures of mica. Mica can be ground into small flakes and added to paints to make them shiny and iridescent. In either case, it is a very economically risky mining procedure because of the cost involved in locating the vein and the unpredictability of the quality and quantity of the mica that might be recovered once the vein is located and worked. Although the micas are generally considered to be monoclinic (pseudohexagonal), there also are hexagonal, orthorhombic, and triclinic forms generally referred to as polytypes. Mica is the name given to a group of silicate minerals which can be ground down into a sparkling powder for use in beauty products, causing it to be referred to as \"nature's glitter\". Sheet mica is recovered by either sinking a shaft along the strike and dip of a pegmatite or by open-pit surface mining of semi-hard pegmatite ore. Lepidolite, generally pinkish to lilac in colour, occurs in lithium-bearing pegmatites. MICA is a nationally recognized leader in innovative art and design education. In the paint industry, ground mica is used as a pigment extender that also facilitates suspension due to its light weight and platy morphology. The SciFest All Access virtual science festival will offer engaging STEM activities and performances extended through October 31, 2020, that celebrate the excitement of STEM for K-12 students, college students, educators, and families.  The MEC Virtual Booth has the new MEC Careers in Mining video and more!  Register here. There are, however, no complete series of solid solutions between any dioctahedral mica and any trioctahedral mica. Mica is a silicate mineral used in cosmetics for its brilliant or shimmering appearance, according to Wikipedia. Mica capacitor is a reliable and high precision capacitor that uses mica as the dielectric to store electric charge. In soft residual material, dozers, shovels, scrapers and front-end loaders are used in the mining process. The general formula for minerals of the mica group is XY2–3Z4O10(OH, F)2 with X = K, Na, Ba, Ca, Cs, (H3O), (NH4); Y = Al, Mg, Fe2+, Li, Cr, Mn, V, Zn; and Z = Si, Al, Fe3+, Be, Ti. The colour and occurrence of this mineral in sediments and sedimentary rocks formed from those sediments generally are sufficient for identification. Mica is a mineral name given to a group of minerals that are physically and chemically similar.  They are all silicate minerals, known as sheet silicates because they form in distinct layers.  Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible. The FDA defines natural mica as: The color additive mica is a white powder obtained from the naturally occurring mineral, muscovite mica, consisting predominantly of a potassium aluminum silicate, K2Al4 (Al2Si6O20) (OH)4 or, alternatively, H2KAl3 (SiO4)3. Glauconite, which most often occurs as pelletlike grains, has no apparent cleavage. Most biotites are 1M and most muscovites are 2M; however, more than one polytype is commonly present in individual specimens. Ring in the new year with a Britannica Membership. The design and re-launch of the new MEC website is madepossible by a generous contribution from Newmont Mining, The SciFest All Access virtual science festival will offer engaging STEM activities and performances, The design and re-launch of the new MEC website is made. Once the mica stone is ground into a powder, mica powder is created. It has traces of metals like potassium, iron, aluminum, and magnesium. Lepidolites are nearly colourless, pink, lavender, or tan. The charge is balanced by singly charged large cations—for example, potassium in muscovite—that join the cross-linked double layers to form the complete structure. MICAT 2021: MICAT is the mandatory entrance test for admission to PGDM programs at MICA Ahmedabad. FOUND IN: Makeup products, shingles, wallpaper, insulation, cement and asphalt. Mica is one such mineral, and it is a silicate mineral. The differences among mica species depend upon differences in the X and Y cations. In chemistry, a silicate is any member of a family of anions consisting of silicon and oxygen. Phlogopite, typically brown, and paragonite, which is macroscopically indistinguishable from muscovite, also are fairly common. The MICA brand assures effective delivery of Strategic Marketing and Communication solutions to the industry, government, and community. Updates? Specific gravity for the micas varies with composition. Mica definition is - any of various colored or transparent mineral silicates crystallizing in monoclinic forms that readily separate into very thin leaves. It is used in pigmented products like powdered foundation to provide opacity and give pigments a pearly, shiny appearance. The American Heritage® Student … Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. A mineral is an inorganic solid found in nature. Mica is a natural stone mineral with shiny flakes. Types of mica capacitors. In Move Mining Next Gen, students from grades K-12 create and submit short, 3-minute videos to answer the question, “Why is mining important in our lives?”  There are prizes for a grades K-5 category ($250), a grades 6-8 category ($250) and a grades 9-12 category ($250), as well as an overall winner ($1,000).  There is an additional prize ($500) for the video that receives the most votes online—the People’s Choice winner.  Go to www.MoveMiningNextGen.org to learn how to make and submit your video! There are 37 different mica minerals. Pearl Ex is a popular brand of pure mica powder. Our editors will review what you’ve submitted and determine whether to revise the article. Mica, any of a group of hydrous potassium, aluminum silicate minerals. (The elasticity of the thin sheets distinguishes the micas from similarly appearing thin sheets of chlorite and talc.) While this doesn't specifically relate to mica in cosmetics, it does suggest that it may be a good idea to be in a well-ventilated area when applying mica … Flake mica can be obtained from several sources: the metamorphic rock called schist as a by… The mica industry can be divided into two distinct but interdependent industries: those that produce sheet mica, and those that produce flake mica. Hardness is used to distinguish micas from chloritoid, which also occurs rather commonly as platy masses in some metamorphic rocks; chloritoid, with a Mohs hardness of 61/2, cannot be scratched with a knife blade or geologic pick. Mica is heat-resistant and does not conduct electricity. The names of the rock-forming micas constitute a good example of the diverse bases used in naming minerals: Biotite was named for a person—Jean-Baptiste Biot, a 19th-century French physicist who studied the optical properties of micas; muscovite was named, albeit indirectly, for a place—it was originally called “Muscovy glass” because it came from the Muscovy province of Russia; glauconite, although typically green, was named for the Greek word for blue; lepidolite, from the Greek word meaning “scale,” was based on the appearance of the mineral’s cleavage plates; phlogopite, from the Greek word for firelike, was chosen because of the reddish glow (colour and lustre) of some specimens; paragonite, from the Greek “to mislead,” was so named because it was originally mistaken for another mineral, talc. They are all silicate minerals, known as sheet silicates because they form in distinct layers. Sheet mica is used principally in the electronic and electrical industries. The flake mica produced in the U.S. 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. any of a group of lustrous rock-forming minerals consisting of hydrous silicates of aluminium, potassium, etc, in monoclinic crystalline form, occurring in igneous and metamorphic rock. Among the principal rock-forming minerals, micas are found in all three major rock varieties—igneous, sedimentary, and metamorphic. Mica is heat-resistant and does not conduct electricity. The major uses of sheet and block mica are as electrical insulators in electronic equipment, thermal insulation, gauge “glass”, windows in stove and kerosene heaters, dielectrics in capacitors, decorative panels in lamps and windows, insulation in electric motors and generator armatures, field coil insulation, and magnet and commutator core insulation. Because of their resistance to electricity and heat they are used as dielectrics, in heating elements, etc Compositions of the common rock-forming micas are given in the table. The rock-forming micas (other than glauconite) can be divided into two groups: those that are light-coloured (muscovite, paragonite, and lepidolite) and those that are dark-coloured (biotite and phlogopite). Basically, Mica is a mineral. Of the 28 known species of the mica group, only 6 are common rock-forming minerals. MICA is the simple, efficient, and comprehensive solution that provides benefits for the insurance carrier, the adjuster and the contractor. Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible. Mica - Mica - Origin and occurrence: Micas may originate as the result of diverse processes under several different conditions. The end faces are parallel to the perfect cleavage that characterizes the group. The most common include: purple lepidolite, black biotite, brown phlogopite and clear muscovite. The word "mica" is actually thought to be derived from … Let us know if you have suggestions to improve this article (requires login). They’re used to give a metallic or shimmery pearl-like effect. The lustre of the micas is usually described as splendent, but some cleavage faces appear pearly. Mica and Its Uses . Apart from taking CAT 2020 or XAT 2021, you need to appear in MICAT. As the oldest continuously degree-granting college of art and design in the nation, MICA is located in Baltimore, deeply connected to the community. Most minerals do not have a perfect basal cleavage, which is how smoothly a mineral retains its surface if part of it is cut or broken off. Similar variations in composition are known for the other micas. Add to Favorites Request Information Print Page Email Page Export Selected. The most common include: purple lepidolite, black biotite, brown phlogo… Mica is common in igneous and metamorphic rocks. Biotites and phlogopites also exhibit the property termed pleochroism (or, more properly for these minerals, dichroism): When viewed along different crystallographic directions, especially using transmitted polarized light, they exhibit different colours or different absorption of light or both. The minerals that mica comes from having a fragile, layered crystalline structure gives it a pearlescent and metallic look. This feature cannot, however, be determined macroscopically; polytypes are distinguished by relatively sophisticated techniques such as those employing X-rays. Emeritus Professor of Geology, Central Michigan University, Mount Pleasant. Mica is a naturally occurring mineral dust often used in makeup foundations, as filler in cement and asphalt, and as insulation material in electric cables. The rubber industry uses ground mica as an inert filler and as a mold lubricant in the manufacture of molded rubber products, including tires. The Mentally Ill Chemical Abuse (MICA) Treatment Program. The Mentally Ill Chemical Abuse (MICA) Treatment Program. Home Mining & Minerals Information Minerals Database. Mica powders are therefore sparkly, sort of like very fine glitter. Mica often occurs as flakes, scraps, or sheets, and has been used by humans since prehistoric times. Phlogopites resemble biotites but are honey brown. According to the Mineral Information Institute, the word "mica" is related to the Latin word "micare," which means "to shine." When mica is ground into a powder, you get mica powder. Better of the two MICAT Scores will be considered to select the candidates. Mica is a colorless, odorless solid that easily flakes into powder. natural occurring mineral that is based on a collection of silicate minerals and composed of varying amounts of potassium Author of. All of these micas except glauconite exhibit easily observable perfect cleavage into flexible sheets. Glauconite, a green species that does not have the same general macroscopic characteristics as the other micas, occurs sporadically in many marine sedimentary sequences. Mica, any of a group of hydrous potassium, aluminum silicate mineral s. It is a type of phyllosilicate, exhibiting a two-dimensional sheet or layer structure. The minutely crystalline variety consisting of muscovite or paragonite (or both), generally referred to as sericite, is silky. MICA is redefining the role of the artists and designers as creative, solutions-oriented makers and thinkers who will drive social, cultural, and economic advancement for our future. Muscovite, the common light-coloured mica, and biotite, which is typically black or nearly so, are the most abundant. In underground mining, the main shaft is driven through the pegmatite at suitable angles to the dip and strike using air drills, hoists and explosives. Mica is derived from a natural stone mineral that boasts shiny flakes. After blasting, the mica is hand-picked and placed in boxes or bags for transporting to the trimming shed where it is graded, split, and cut to various specified sizes for sale. Properties of the latter are described separately later in the discussion. Mica likely got its name from Latin, where the word “micare” means to shine. Micah definition is - a prophetic book of canonical Jewish and Christian Scripture. Any of a group of aluminum silicate minerals that can be split easily into thin, partly transparent sheets. Mica is the general name given to a group of 37 crystalline silicate minerals. Thus, as in some of the other groups of minerals (e.g., the garnets), different individual pieces of naturally occurring mica specimens consist of different proportions of ideal end-member compositions. The principal use of ground mica is in gypsum wallboard joint compound, where it acts as a filler and extender, provides a smoother consistency, improves workability, and prevents cracking. The perfect cleavage into thin elastic sheets is probably the most widely recognized characteristic of the micas. Muscovites range from colourless, greenish to blue-green to emerald-green, pinkish, and brownish to cinnamon-tan. Lepidolite. Insurance carriers get the benefit of a real-time audit by exceptions and improved cycle time due … It is highly resistant to heat and is used in electric fuses and other electrical equipment. Mica is a naturally-occurring mineral. Consequently, micas can be scratched in either direction with a knife blade or geologic pick. 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