hematite

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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 (ocherocher
, mixture of varying proportions of iron oxide and clay, used as a pigment. It occurs naturally as yellow ocher (yellow or yellow-brown in color), the iron oxide being limonite, or as red ocher, the iron oxide being hematite.
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) 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. See limonitelimonite
or brown hematite
, yellowish to dark brown mineral, a hydrated oxide of iron, FeO(OH)·nH2O, occurring commonly in deposits of secondary origin, i.e., those formed by the alteration of minerals containing iron.
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Hematite

 

a widely distributed ferrous mineral, Fe203, containing up to 70 percent iron. Hematite is crystallized in a trigonal system. Its crystals are steel gray with a semimetallic shine. Depending on the mineral aggregate structures and the crystallic concretion shapes, a distinction is made among (1) hematite iron glance (macrocrystalline concretions); (2) ferrous mica (flaky aggregates); (3) ferrous rosette (crystal concretions reminiscent of corollas of dog rose); (4) red ironstone (dense red microcrystallic units); (5) kidney ore (red dense reniform conglomerations); and (6) martite (dense or porous ore formations). On the mineralogical scale, the hardness is 5.5-6; the density, 5,260 kg per cu m. The powder is cherry red in color. The melting point is 1594° C.

Together with magnetite, geothite, and quartz, hematite is formed in deposits of different genetic types and in various rocks, when the oxidizing potential of the medium is sufficiently high. Hematite ores are ferrous ores of great importance, being used for smelting cast iron and steel. Iron content in solid hematite ores fluctuates from 50 percent to 65 percent. The largest deposits are connected with the oldest Precambrian ferriferous quartzites (jaspilites).

In the USSR the Krivoi Rog hematite ore deposit (in the Ukrainian SSR), the Kursk Magnetic Anomaly, and the Urals and Siberian deposits are well known. The biggest deposits abroad are situated near Lake Superior, Birmingham, and elsewhere in the USA; in the state of Minas Gerais in Brazil; and in Canada (Labrador), India (states of Bihar, Orissa, and Madhya Pradesh), and several countries of Africa.

hematite

[′hē·mə‚tīt]
(mineralogy)
Fe2O3 An iron mineral crystallizing in the rhombohedral system; the most important ore of iron, it is dimorphous with maghemite, occurs in black metallic-looking crystals, in reniform masses or fibrous aggregates, or in reddish earthy forms. Also known as bloodstone; red hematite; red iron ore; red ocher; rhombohedral iron ore.
References in periodicals archive ?
A few grains of Fe-oxides, dolomite, muscovite, biotite, plagioclase feldspars, chlorite, limonite, haematite, rutile, and ilmenite were also present.
As maghaemite subsequently inverts to haematite during heating, the cooling curve loses susceptibility (about 60%).
The reopening of Iron Baron is the latest chapter in Arrium Mining s haematite extension program that aims to extend the life of its operation in the Middleback Ranges.
The larger of the two haematite occurrences has an exploration target potential of 20 to 25 million tonnes at a grade of 55-60% Fe.
For this reason, we have re-focused our exploration activities on to this project, and have so far been rewarded with outstanding haematite bearing intersections of up to 33.
New prospecting, detailed magnetic surveying and a revised prospectivity model have upgraded the potential for shallow haematite as Direct Shipping Ore (DSO).
9 million metric tons per year (mt/y) of haematite ore, at a stripping ratio of 3.
Tenders are invited for Supply Of Iron Ore Concentrate Haematite From Indigenous Sources.
Haematite is a very hard stone, whereas red ochre is finely ground powder, or paste.
The fragments of vitrified ceramics, tuyere, quartz, haematite and dense slag with flow marks found during the excavation suggest that these structures were furnaces used for iron smelting.
The railway line was opened in 1889 to carry lead and haematite to Prestatyn from local works and was upgraded to carry passengers in 1903.
Proxies for the environmental factors used in the spatial modelling Theme Name of surrogate Description variable Soil and Kaolinite, Mite, Clay mineral abundances parent Smectite material PCI, PC2, PC3 First three principal components of vis-NIR spectra representing soil organic and mineral composition: PCI represents soil with abundant haematite PC2 represents soil rich in organic matter PC3 represents soil with which abundant smectite, illite and goethite Total dose, K, Gamma radiometrics dose and U and Th concentrations in % and mg [kg.