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iron ores

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    islamiccastel
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    iron ores

    iron ores

    Iron ores are rocks and minerals from which metallic iron can be extracted. The ores are usually rich in iron oxides and vary in colour from dark grey to rusty red. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), limonite or siderite. Hematite is also known as "natural ore". The name refers to the early years of mining, when certain hematite ores contained 66% iron and could be fed directly into steel-making blast furnaces. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel.[1] Iron ore cargoes may affect magnetic compasses
    magnetite
    [IMG]http://*******.answers.com/main/*******/wp/en/thumb/7/75/250px-Magnetite_Russia.jpg[/IMG]

    Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of
    the spinel group. The chemical IUPAC name is iron(II,III) oxide and the common chemical name ferrous-ferric oxide.

    The Curie temperature of magnetite is about 580°C. Magnetite is the most magnetic of all the naturally occurring minerals on Earth, and these magnetic properties led to lodestone being used as an early form of magnetic compass. Magnetite typically carries the dominant magnetic signature in rocks, and so it has been a critical tool in paleomagnetism, a science important in discovering and understanding plate tectonics. The relationships between magnetite and other iron-rich oxide minerals such as ilmenite, hematite, and ulvospinel have been much studied, as the complicated reactions between these minerals and oxygen influence how and when magnetite preserves records of the Earth's magnetic field..

    hematite
    [IMG]http://*******.answers.com/main/*******/wp/en/thumb/c/c1/250px-HematiteUSGOV.jpg[/IMG]

    Hematite (hĕm'ətīt) , mineral, an oxide of iron, Fe2O3, containing about 70% metal, occurring in nature in red to reddish-brown earthy masses and in steel-gray to black crystalline forms. Hematite that has a metallic luster is called specular hematite, or specular iron. The red powdered hematite is used as a pigment (ocher) and as rouge in polishing. Hematite is the most important ore of iron. Extensive and richly productive deposits occur in the Lake Superior region (Michigan, Minnesota, and Wisconsin) and the Birmingham district (Alabama). The mineral is widely distributed throughout the world and is responsible for the red coloration of many sedimentary rocks.


    limonite
    [IMG]http://*******.answers.com/main/*******/wp/en/thumb/f/ff/180px-LimoniteUSGOV.jpg[/IMG]



    Limonite is an ore consisting in a mixture of hydrated iron(III) oxide-hydroxide of varying composition. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as limonite often contains a varying amount of oxide compared to hydroxide.


    Together with hematite, it has been mined as ore for the production of iron. Limonite is heavy and yellowish-brown. It is a very common amorphous substance though can be tricky to find when mined with hematite and bog ore.


    It is not a true mineral and it is composed by a mixture of similar hydrated iron oxide minerals, mostly goethite with lepidocrocite, jarosite, and others. Limonite forms mostly in or near oxidized iron and other metal ore deposits and as sedimentary beds. Limonite may occur as the cementing material in iron rich sandstones. Also known as the Lemon Rock.


    It is never crystallized into macroscopic crystals, but may have a fibrous or microcrystalline structure, and commonly occurs in concretionary forms or in compact and earthy masses; sometimes mammillary, botryoidal, reniform or stalactitic. The colour presents various shades of brown and yellow, and the streak is always brownish, a character which distinguishes it from hematite with a red, or from magnetite with a black streak. It is sometimes called brown hematite or brown iron ore

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    محب يونس
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    تاريخ التسجيل: Mar 2007
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    some ore as clay mineral

    how to measur percentage of iron

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