graphite


graphite
graphitic /greuh fit"ik/, adj.
/graf"uyt/, n.
a very common mineral, soft native carbon, occurring in black to dark-gray foliated masses, with metallic luster and greasy feel: used for pencil leads, as a lubricant, and for making crucibles and other refractories; plumbago; black lead.
[1790-1800; < G Graphit < Gk gráph(ein) to write, draw + G -it -ITE1]

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Mineral allotrope of carbon.

It is dark gray to black, opaque, and very soft. Its layered structure, with rings of six atoms arranged in widely spaced parallel sheets, gives it its slippery quality. It occurs in nature and is used (mixed with clay) as the "lead" in pencils. It is also used in lubricants, crucibles, polishes, arc lamps, batteries, brushes for electric motors, and nuclear reactor cores.

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carbon
also called  plumbago , or  black lead 

      mineral consisting of carbon. Graphite has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets. Graphite thus crystallizes in the hexagonal system, in contrast to the same element crystallizing in the octahedral or tetrahedral system as diamond. Such dimorphous pairs usually are rather similar in their physical properties, but not so in this case. Graphite is dark gray to black, opaque, and very soft (with a hardness of 1 1/2 on the Mohs scale), while diamond may be colourless and transparent and is the hardest naturally occurring substance. Graphite has a greasy feel and leaves a black mark, thus the name from the Greek verb graphein, “to write.” For detailed physical properties of graphite, see native element (table).

      Graphite is formed by the metamorphosis of sediments containing carbonaceous material, by the reaction of carbon compounds with hydrothermal solutions or magmatic fluids, or possibly by the crystallization of magmatic carbon. It occurs as isolated scales, large masses, or veins in older crystalline rocks, gneiss, schist, quartzite, and marble and also in granites, pegmatites, and carbonaceous clay slates. Small isometric crystals of graphitic carbon (possibly pseudomorphs after diamond) found in meteoritic iron are called cliftonite.

      Graphite is used in pencils, lubricants, crucibles, foundry facings, polishes, arc lamps, batteries, brushes for electric motors, and cores of nuclear reactors. It is mined extensively in Sri Lanka; Madagascar; North Korea; Sonora, Mex.; Ontario; western Siberia; and New York.

      Graphite was first synthesized accidentally by Edward G. Acheson (Acheson, Edward Goodrich) while he was performing high-temperature experiments on carborundum. He found that at about 4,150° C (7,500° F) the silicon in the carborundum vaporized, leaving the carbon behind in graphitic form. Acheson was granted a patent for graphite manufacture in 1896, and commercial production started in 1897. Since 1918, petroleum coke, small and imperfect graphite crystals surrounded by organic compounds, has been the major raw material in the production of 99 to 99.5 percent pure graphite.

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Universalium. 2010.

Synonyms:

Look at other dictionaries:

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  • graphite — [ grafit ] n. m. • 1799; du gr. graphein « écrire » ♦ Variété naturelle de carbone cristallisé formée de carbone presque pur. Le graphite est employé dans la fabrication des crayons. ⇒ plombagine (cf. Mine de plomb). Électrodes de graphite.… …   Encyclopédie Universelle

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  • Graphite — Graph ite, n. [Gr. gra fein to write: cf. F. graphite. See {Graphic}.] (Min.) Native carbon in hexagonal crystals, also foliated or granular massive, of black color and metallic luster, and so soft as to leave a trace on paper. It is used for… …   The Collaborative International Dictionary of English

  • Graphite — См. Графит Термины атомной энергетики. Концерн Росэнергоатом, 2010 …   Термины атомной энергетики

  • graphite — (n.) 1796, from Ger. Graphit black lead, coined 1789 by German mineralogist Abraham Gottlob Werner (1750 1817) from Gk. graphein write (see GRAPHY (Cf. graphy)) + mineral suffix ITE (Cf. ite). So called because it was used in pencils. Related:… …   Etymology dictionary

  • graphite — ► NOUN ▪ a grey form of carbon used as a solid lubricant and as pencil lead. DERIVATIVES graphitic adjective. ORIGIN from Greek graphein write (because of its use in pencils) …   English terms dictionary

  • graphite — [graf′īt΄] n. [Ger graphit < Gr graphein, to write (see GRAPHIC): from its use as writing material] a very soft, black, hexagonal mineral of pure carbon, formed in thin plates and found in metamorphic rocks: used in making electrodes, paints,… …   English World dictionary

  • Graphite — For other uses, see Graphite (disambiguation). Graphite Graphite specimen General Category Native element mineral …   Wikipedia


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