how is limonite formed

Apr 29, 2018· Limonite has an earthy luster that sometimes may have a sub metallic or dull finish. Limonite is a secondary product formed from the oxidation of other iron minerals. Limonite comes in a variety of different colors – ranging from brown to yellow. Historically, Limonite has been used as a pigment - raw umber, sienna, and ocher.

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Oct 25, 2012· Gold vein stockwork in limonite from Colorado, USA. (public display, Denver Museum of Nature & Science, Denver, Colorado) The Colorado rock shown above, nicknamed "Tom's Baby", is an extremely high-grade gold ore. It was found in 1887 at Farncomb Hill, Colorado by two miners, Tom Grove and Harry Lytton. The rock was carried from the mine by Tom Grove, who held it as if he was …

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Limonite is a common ore of iron and is always secondary in its origin, formed through the alteration or solution of previously existing iron minerals. Pyrite is often found altered to limonite, the crystal form being at times preserved, giving limonite pseudomorphs.

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The name limonite properly should be restricted to impure hydrated iron oxide (with variable water content) that is colloidal, or amorphous, in character. Often brown and earthy, it is formed by alteration of other iron minerals, such as the hydration of hematite or the oxidation and hydration of siderite or pyrite.

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The localities below have been described as containing limonite, but the sources do not give enough information to determine exactly which minerals are present. FLORENCE COUNTY: Limonite occurs as a component of the oxidized ore formed on iron formation in a number of small iron mines in T.40N. R.18E., where it occurs with magnetite, grunerite ...

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Hematite's Streak: All specimens of hematite will produce a reddish streak. The streak of a mineral is its color in powdered form when scraped across a streak plate (a small piece of unglazed porcelain used to produce a small amount of mineral powder). Some specimens of hematite will produce a brilliant red streak, others will produce a reddish brown streak.

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Limonite is a matrix base of many other minerals, and the term gossan is used as a reference to Limonite when it is used as a a matrix for another mineral or has formed an undesirable staining on top of it. Limonite is extremely common and forms the coloring matter in many soils.

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Currently used for unidentified massive hydroxides and oxides of iron, with no visible crystals, and a yellow-brown streak. 'Limonite' is most commonly the mineral species goethite, but can also consist of varying proportions of lepidocrocite, hisingerite, pitticite, jarosite group species, maghemite, hematite, etc.

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Environment: Limonite is a secondary material and often accumulates due to its own resistance to weathering. Limonite is formed as a result of iron-rich materials like hematite or magnetite weathering (1). Limonite commonly forms as a precipitate around mine entrances, springs, bogs, and other shallow marine areas (1).

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Goethite varies in colour from yellow-brown to red. It is composed of about 80 to 90 percent Fe 2 O 3 and approximately 10 percent water. When dehydrated, goethite forms hematite; upon hydration, goethite becomes limonite. For detailed physical properties, see oxide mineral (table).

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Oct 26, 2008· Limonite is a recognized mineral by the IMA, although its chemical structure will vary. As a mineral, it is not classified as igneous, sedimentary, or metamorphic in the manner of rock identification

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Uses of limonite. One of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous, while the darker forms produced more earthy tones. Roasting the limonite changed it partially to hematite, producing red ochres, burnt umbers and siennas.

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Limonite often forms a cementing medium in ferruginous sands and gravels, forming "pan"; and in like manner it is the agglutinating agent in many conglomerates, like the South African "banket," where it is auriferous. In iron-shot sands the limonite may form hollow concretions, known in …

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Limonite is not a true mineral but a mixture of similar hydrated iron oxide minerals. Most of limonite is made up of Goethite. Massive Goethite and Limonite can be indistinguishable. Limonite forms mostly in or near oxidized iron and other metal ore deposits, and as sedimentary beds.

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A quartz–barite– limonite vein up to 3 m wide crops out near the hilltop. An inclined drill hole in the 1990s intersected only minor copper and gold mineralization. The boulders and pyrite precursor of the limonite suggest a hypogene advanced argillic or high sulfidation epithermal system.

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Products Produced From Limonites - Mining machinery for ... how does limonite formed – ZENIT. Limonite – Wikipedia, the free encyclopedia. Individual minerals in limonite may form crystals, but limonite does not, ...

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Limonite is formed under exogenous conditions upon decomposition of pyrite and other iron-bearing sulfides, siderite, and iron silicates. It occurs in gossan, laterite, bog ore, and other similar-type formations. Limonite forms large industrial deposits of high-grade iron ore.

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Limonite has been known to form pseudomorphs after other minerals such as pyrite, meaning that the chemical weathering transforms the crystal of pyrite into limonite but keeps the external shape of the pyrite crystal. It has also been formed from other iron oxides, hematite and magnetite; the carbonate siderite and iron rich silicates like some ...

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Limonite does not form in crystals. It occurs amorphous in earthy, massive, botryoidal, mammilary stalactitic and fibrous form. May also form as a pseudomorph after other minerals, especially Pyrite, Siderite, and Marcasite. Uses of Limonite. Limonite in an ore of iron and is used as a pigment in the manufacture of paints.

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Iron oxide concretions, iron oxide nodules, and ironstones are often mistaken for meteorites because their unusual shapes catch people's attention and they are denser than most other rocks. Hematite concretions form by precipitation of iron oxide from iron rich solutions.

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Limonite is common and occurs within concretions and cavity fillings in sedimentary rocks and as coatings on the rocks, especially sandstone. It also occurs as iron rust and accumulates around rootlets in soils. Small amounts of limonite discolor limestone, dolomite, clay, shale, sandstone, and gravel.

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Apr 29, 2018· Limonite after Pyrite is formed when pyrite begins to decompose through chemical weathering and the iron present in the mineral starts to rust. Limonite is any impure hydrated iron oxide. Limonite is mostly clay but also may contain phosphates and silica. Once the rust has started, Limonite slowly starts to form.

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Limonite is formed under exogenous conditions upon decomposition of pyrite and other iron-bearing sulfides, siderite, and iron silicates. It occurs in gossan, laterite, bog ore, and other similar-type formations. Limonite forms large industrial deposits of high-grade iron ore.

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Turquoise is an opaque, blue-to-green mineral with the chemical formula CuAl6(PO4)4(OH)8·4H2O, a hydrated copper and aluminum phosphate. It is common and useful in higher grades and has been appreciated for thousands of years as a gemstone and ornamental stone due …

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Limonite is a recognized mineral by the IMA, although its chemical structure will vary. As a mineral, it is not classified as igneous, sedimentary, or metamorphic in the manner of rock ...

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Bog iron ore is an impure limonite, usually formed by the influence of micro-organisms, and containing silica, phosphoric acid and organic matter, sometimes with manganese. The various kinds of brown and yellow ochre are mixtures of limonite with clay and other impurities; whilst in umber much manganese oxide is present. ...

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Several large and fairly rare Pyritohedral Limonite pseudomorphs after pyrite, a form well noted for this particular locality, and a highly prized find over the more commonly occuring cubic variety. Specimens from the Fruitville Pike Limonite Locality, just North of Lancaster, Lancaster Co., Pennsylvania (Dana locality). Acquired from the Jay ...

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May also form as a pseudomorph after other minerals, especially Pyrite, Siderite, and Marcasite.As a secondary mineral formed from the alteration of iron minerals.Limonite in a ore of iron and is used as a pigment in the manufacture of paints.

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Uses of limonite. One of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous, while the darker forms produced more earthy tones. Roasting the limonite changed it partially to hematite, producing red ochres, burnt umbers and siennas.

Get Price