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 ?
This process results in characteristic red, hematitic nodules with a yellow, goethitic cortex.
It is a hematitic schist (about 23% of the deposit) and similar to the Rosa mineralization.
Gold Recovery by Ore Type Recovery per Mine Plan Life of Mine Cutoff Grade (Au) (g/mt) Crusher Ore: Hematitic 80% 0.
The host rocks for most of the mineral occurrences and the unit overlying the most intense portion of the magnetic anomaly is a brecciated, hematitic felsic volcanic rock, locally with veins of purple fluorite and disseminated pyrite.
The core of essentially barren hematite-quartz breccias is surrounded by complexly intermingled granitic and hematitic breccias about 1 km in width and extending almost 5 km in a NW-SE direction.
Mineralization previously documented on Eagle Nest is very fine-grained to visible flaky gold, with oxidized copper ores and staining, in a linear, lenticular ore body with a steeply dipping fault zone cutting metamorphic Mesozoic, red, hematitic shale.
Strong argillic and hematitic alteration was observed at approximately 845 feet when the hole passed from upper-plate chert into carbonate rocks presumed to be part of the lower plate assemblage.
Veins cut in the trenching and drilling comprise vein breccias with strong silicification, hematitic gossans, and oxide copper minerals.
The helicopter-borne geophysical data will further delineate the strike and extent of known radioactive mineralization; map any radioactive boulder trains, help define hematitic fractures, map structures, identify any mafic intrusives, and map the extent of the sedimentary basin.
The El Realito project is unique in the Mulatos district in that it contains an extensive area of intense hematitic oxidation with local visible gold in outcrop.
The hole was begun on June 15, 2004 in an area of intensive hematitic breccia.