hematite

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Related to hematitic: red hematite, specularite, specular hematite

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 ?
Further holes are underway at Grouse Island, near where zones of similar hematitic, brecciated and dravite altered and sandstone mineralization was mapped this past summer.
Freshly broken surfaces exhibit interstitial matrix that ranges from fine-grained, clean quartz sandstone and siltstone, hematitic claystone and cements.
At Cerro Oro gold-silver mineralization is hosted in sericitic and argillically altered 2-3MA volcanic tuffs and flows of the Combia Formation associated with extensive multidirectional hematitic fractures zones.
It is expected that Eklama complex will produce high-grade hematitic iron ore.
The sulphide mineralisation was primarily pyrite with minor chalcopyrite (copper sulphide) accompanied by strong chlorite and in places siliceous and hematitic (jasperoidal) alteration.
Below the unconformity, the drillholes intercepted hematitic alteration zones with similarities to typical feeder zones for classical unconformity style deposits.
85 for the Rhodic Acrudox and 0 for the Xanthic Acrustox, indicating that the former can be classified as hematitic (Hm/Hm+Gt >0.
The Round Top project rhyolite was divided into five different alteration phases based on the intensity of hematitic and hydrothermal alteration.
The mineralisation is primarily pyrite with minor chalcopyrite (copper sulphide) accompanied by strong chlorite and in places siliceous and hematitic (jasperoidal) alteration.
5 g/t Au in a zone with hematitic alteration, disseminated pyrite and quartz-carbonate stringers.
The project covers the eastern limb and fold hinge area of the Millidie Syncline, including the Robinson Range Formation, which is a Proterozoic sequence of banded iron-formation, siltstone and hematitic shale.
A gradual progression from Fe sandstone clasts to hematitic concentric nodules with a goethitic cortex and then to goethitic uniform/ gradational nodules can be observed.