NationMaster - Encyclopedia: Hematite

Hematite, also spelled hæmatite, is the mineral form of Iron(III) oxide (Fe₂O₃), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and as corundum. Hematite and ilmenite form a complete solid solution at temperatures above 950°C. Hematite. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Iron(III) oxide â€” also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust â€” is one of the several oxide compounds of iron, and has paramagnetic properties. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups. ... A regular hexagon A hexagon (also known as sexagon) is a polygon with six edges and six vertices. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For other uses, see Fracture (disambiguation). ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope. ... The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across a unweathered surface. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... The differences in the spellings of British English and American English are as follows: Spelling differences between U.S. usage on one side and British and Commonwealth usage on the other are generally more conspicuous than spelling differences within the Commonwealth. ... For other uses, see Mineral (disambiguation). ... Iron(III) oxide â€” also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust â€” is one of the several oxide compounds of iron, and has paramagnetic properties. ... Iron oxide pigment There are a number of iron oxides: Iron oxides Iron(II) oxide or ferrous oxide (FeO) The black-coloured powder in particular can cause explosions as it readily ignites. ... In crystallography, the rhombohedral (or trigonal) crystal system is one of the 7 lattice point groups. ... For other uses, see Crystal (disambiguation). ... Ilmenite is a weakly magnetic iron-black or steel-gray mineral found in metamorphic and igneous rocks. ... Corundum (from Tamil kurundam) is a crystalline form of aluminium oxide and one of the rock-forming minerals. ... Fig. ...

Hematite is a mineral, colored black to steel or silver-gray, brown to reddish brown, or red. It is mined as the main ore of iron. Varieties include kidney ore, martite (pseudomorphs after magnetite), iron rose and specularite (specular hematite). While the forms of hematite vary, they all have a rust-red streak. Hematite is harder than pure iron, but much more brittle. Download high resolution version (1641x1581, 712 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1641x1581, 712 KB) Wikipedia does not have an article with this exact name. ... This article is about mineral extractions. ... This heap of iron ore pellets will be used in steel production. ... In geology, a pseudomorph is a mineral compound resulting from a substitution process in which the appearance and dimensions remain constant, but the mineral which makes up the chief component of the compound is replaced by another. ... Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. ...

Huge deposits of hematite are found in banded iron formations. Grey hematite is typically found in places where there has been standing water or mineral hot springs, such as those in Yellowstone. The mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water. Hematite can also occur without water, however, usually as the result of volcanic activity. 2. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57 F or... Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. ... Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station For other uses, see Volcano (disambiguation). ...

Clay-sized hematite crystals can also occur as a secondary mineral formed by weathering processes in soil, and along with other iron oxides or oxyhydroxides such as goethite, is responsible for the red color of many tropical, ancient, or otherwise highly weathered soils. For other uses, see Clay (disambiguation). ... Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earths atmosphere. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland For the American hard rock band, see SOiL. For the System of a Down song, see Soil (song). ... Goethite, named after the German polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low temperature environments. ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ...

The name hematite is derived from the Greek word for blood (haima) because hematite can be red, as in rouge, a powdered form of hematite. The color of hematite lends it well in use as a pigment. Iron(III) oxide â€” also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust â€” is one of the several oxide compounds of iron, and has paramagnetic properties. ... Natural Ultramarine pigment in powdered form. ...

Good specimens of hematite come from England, Mexico, Brazil, Australia and the Lake Superior region of the United States and Canada. Image File history File linksMetadata Download high resolution version (1100x821, 226 KB) Summary Rainbow Hematite from Minas Gerais, Brazil. ... Image File history File linksMetadata Download high resolution version (1100x821, 226 KB) Summary Rainbow Hematite from Minas Gerais, Brazil. ... SEM Cambridge S150 at Geological Institute, University Kiel, 1980 SEM opened sample chamber The scanning electron microscope (SEM) is a type of electron microscope capable of producing high-resolution images of a sample surface. ... For other uses, see England (disambiguation). ... For the the Quebec municipality, see Lac-SupÃ©rieur. ...

Magnetism

Hematite is an antiferromagnetic material below the Morin transition at 260 K, and a canted antiferromagnet or weakly ferromagnetic [1] above the Morin transition and below its Néel temperature at 948K, above which it is paramagnetic. In materials that exhibit antiferromagnetism, the spins of magnetic electrons align in a regular pattern with neighboring spins pointing in opposite directions. ... Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ... ... Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field. ...

The magnetic structure of a-hematite was the subject of considerable discussion and debate in the 1950s because it appeared to be ferromagnetic with a Curie temperature of around 1000 K, but with an extremely tiny moment (0.002mB). Adding to the surprise was a transition with a decrease in temperature at around 260 K to a phase with no net magnetic moment.^{[citation needed]} Image File history File links Size of this preview: 640 Ã— 600 pixelsFull resolution (732 Ã— 686 pixel, file size: 114 KB, MIME type: image/jpeg) Source: Chris Ralph. ... Image File history File links Size of this preview: 640 Ã— 600 pixelsFull resolution (732 Ã— 686 pixel, file size: 114 KB, MIME type: image/jpeg) Source: Chris Ralph. ...

Dzialoshinksi and later Moriya showed that the system is essentially antiferromagnetic but that the low symmetry of the cation sites allows spin–orbit coupling to cause canting of the moments when they are in the plane perpendicular to the c axis. The disappearance of the moment with a decrease in temperature at 260 K is caused by a change in the anisotropy which causes the moments to align along the c axis. In this configuration, spin canting does not reduce the energy.^{[citation needed]}

Hematite is part of a complex solid solution oxyhydroxide system having various degrees of water, hydroxyl group, and vacancy substitutions that affect the mineral's magnetic and crystal chemical properties.^[3] Two other end-members are referred to as protohematite and hydrohematite.

Hematite on Mars

The spectral signature of hematite was seen on the planet Mars by the infrared spectrometer on the NASA Mars Global Surveyor ("MGS") and 2001 Mars Odyssey spacecraft in orbit around Mars ^[4]. The mineral was seen in abundance at two sites^[5]. on the planet, the Terra Meridiani site, near the Martian equator at 0° longitude, and the second site Aram Chaos near the Valles Marineris ^[6]. Several other sites also showed hematite, e.g., Aureum Chaos ^[7]. Because terrestrial hematite is typically a mineral formed in aqueous environments, or by aqueous alteration, this detection was scientifically interesting enough that the second of the two Mars Exploration Rovers was targeted to a site in the Terrra Meridiani region designated Meridiani Planum. In-situ investigations by the Opportunity rover showed a significant amount of hematite, much of it in the form of small spherules that were informally tagged by the science team "blueberries" (a term which is somewhat confusing, since in spectrally-correct color images they are, in fact, silver-grey in color). Analysis indicates that these spherules are apparently concretions formed from a water solution. The image is from one of the Mars Exploration Rovers File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The image is from one of the Mars Exploration Rovers File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Spheules still in their originating strata Martian spherules, also known as blueberries, are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Spectrometer A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. ... For other uses, see NASA (disambiguation). ... The Mars Global Surveyor (MGS) was a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... Artists concept of the 2001 Mars Odyssey Spacecraft 2001 Mars Odyssey is an unmanned spacecraft orbiting the planet Mars. ... Sinus Meridiani is a feature name for an albedo feature on Mars stretching east-west just south of that planets equator. ... Aram Chaos is the circular depression in the top left. ... Valles Marineris cuts a wide swath across the face of Mars Valles Marineris (Latin for Mariner Valley, named after the Mariner 9 Mars orbiter of 1971-72 which discovered it. ... Artists Concept of Rover on Mars (credit: Maas Digital LLC) NASAs Mars Exploration Rover (MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers â€” Spirit and Opportunity â€” to explore the Martian surface and geology. ... Mars Exploration Rover Opportunity looks southwest across Meridiani Planum; the Rovers discarded backshell and parachute are visible in the distance Hematite deposits in Meridiani Planum mapped from orbit, with Opportunity rover landing site ellipse Meridiani Planum is a plain located 2 degrees south of Mars equator, in the westernmost... The launch patch for Opportunity, featuring Duck Dodgers (Daffy Duck). ... Spheules still in their originating strata Martian spherules, also known as blueberries, are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars. ... 1. ...

Jewelry

Hematite's popularity in jewelry was at its highest in Europe during the Victorian era, while in the last 50 years it has been popular in North America, especially in the western United States where it is found in jewelry and art created by Native Americans. Care should be taken in handling hematite items due to the material's susceptibility to damage. The Victorian era of the United Kingdom marked the height of the British Industrial Revolution and the apex of the British Empire. ... North American redirects here. ... This article is about the people indigenous to the United States. ...

Encyclopedia > Hematite

Contents

Magnetism

Hematite on Mars

Jewelry

See also

References

External links