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 ?
Haematite ore is found in Canada, Spain, Britain and Russia.
Rock-art described by archaeologists as belonging to the most recent phase of 'freshwater', 'contact' or 'X-ray' styles usually involves substantial amounts of pigment such as white pipe-clay, which, unlike red haematite pigments, does not permeate deep into the grain of the sandstone and therefore exfoliates easily.
Opportunity was working on the Meridiani Planum, a flat plain containing the iron-rich mineral grey haematite.
These resemble the Vendian and Cambrian claystones of the East European craton, where primary haematite pigmentation suggests the absence of organic matter reducer during the early diagenesis of sediments.
He said: ``The old workings are fascinating and are probably one of the finest haematite mines in Wales.
She sports a cross tattoo on the back of her neck and her favourite accessory is her navel ring - a little silver hoop with a haematite ball.
Haematite to make immortal The precious heirloom bones, the family bones.
torso of a female figure, rock crystal frog, lapis lazuli Maat, bone Nechbet, and royal heads, one of obsidian and a second of haematite.
The investigation indicates that the red part contains haematite and has been subjected to strongly oxidizing firing.
The outcropping quartz veins within the shear show abundant haematite, copper oxide and visible gold mineralisation.
Meanwhile, the Minister said the Government was still considering applications for relief by junior haematite miners, after he announced potential haematite royalty deferrals in December.
Using Raman microscopy, in sample Ml we detected cr-quartz, amorphous charcoal, haematite and pyrochroite.