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100-462: Uchkuduk was founded in 1958, after a small prospecting party found deposits of uranium ore . In the late 1960s, the development of open pit and underground mining led to the rapid growth of the settlement, with workers, engineers and technicians from all over the Soviet Union. It was elevated to city status in 1978. Until 1979, Uchkuduk had the status of a " closed secret city ," as it supplied much of

200-434: A body-centered cubic (bcc) crystal structure . As it cools further to 1394 °C, it changes to its γ-iron allotrope, a face-centered cubic (fcc) crystal structure, or austenite . At 912 °C and below, the crystal structure again becomes the bcc α-iron allotrope. The physical properties of iron at very high pressures and temperatures have also been studied extensively, because of their relevance to theories about

300-430: A nuclear spin (− 1 ⁄ 2 ). The nuclide Fe theoretically can undergo double electron capture to Cr, but the process has never been observed and only a lower limit on the half-life of 4.4×10 years has been established. Fe is an extinct radionuclide of long half-life (2.6 million years). It is not found on Earth, but its ultimate decay product is its granddaughter, the stable nuclide Ni . Much of

400-499: A supernova for their formation, involving rapid neutron capture by starting Fe nuclei. In the far future of the universe, assuming that proton decay does not occur, cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into Fe nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting all stellar-mass objects to cold spheres of pure iron. Iron's abundance in rocky planets like Earth

500-622: A Soviet-wide hit named after the city. This Uzbekistan location article is a stub . You can help Misplaced Pages by expanding it . Uranium ore Uranium ore deposits are economically recoverable concentrations of uranium within Earth's crust . Uranium is one of the most common elements in Earth's crust, being 40 times more common than silver and 500 times more common than gold . It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction

600-454: A distorted sodium chloride structure. The binary ferrous and ferric halides are well-known. The ferrous halides typically arise from treating iron metal with the corresponding hydrohalic acid to give the corresponding hydrated salts. Iron reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides, ferric chloride being the most common. Ferric iodide is an exception, being thermodynamically unstable due to

700-755: A large hematite -rich granite breccia complex in the Gawler Craton overlain by approximately 300 metres of flat-lying sedimentary rocks of the Stuart Shelf geological province. Another example for the breccia type is the Mount Gee area in the Mount Painter Inlier, South Australia. Uranium mineralised quartz-hematite breccia is related to Palaeoproterozoic granites with uranium contents of up to 100 ppm. Hydrothermal processes at about 300 million years ago remobilised uranium from these granites and enriched them in

800-553: A macroscopic piece of iron will have a nearly zero overall magnetic field. Application of an external magnetic field causes the domains that are magnetized in the same general direction to grow at the expense of adjacent ones that point in other directions, reinforcing the external field. This effect is exploited in devices that need to channel magnetic fields to fulfill design function, such as electrical transformers , magnetic recording heads, and electric motors . Impurities, lattice defects , or grain and particle boundaries can "pin"

900-689: A maximum of 50,000 t U 3 O 8 ). Sandstone hosted uranium deposits are widespread globally and span a broad range of host rock ages. Some of the major provinces and production centers include: Significant potential remains in most of these centers as well as in Australia, Mongolia, South America, and Africa. This model type can be further subdivided into the following sub-types: Many deposits represent combinations of these types. Tabular deposits consist of irregular tabular or elongate lenticular zones of uranium mineralisation within selectively reduced sediments. The mineralised zones are oriented parallel to

1000-475: A mixture of O 2 /Ar. Iron(IV) is a common intermediate in many biochemical oxidation reactions. Numerous organoiron compounds contain formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often assessed using the technique of Mössbauer spectroscopy . Many mixed valence compounds contain both iron(II) and iron(III) centers, such as magnetite and Prussian blue ( Fe 4 (Fe[CN] 6 ) 3 ). The latter

1100-471: A result, mercury is traded in standardized 76 pound flasks (34 kg) made of iron. Iron is by far the most reactive element in its group; it is pyrophoric when finely divided and dissolves easily in dilute acids, giving Fe . However, it does not react with concentrated nitric acid and other oxidizing acids due to the formation of an impervious oxide layer, which can nevertheless react with hydrochloric acid . High-purity iron, called electrolytic iron ,

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1200-701: A significant tonnage. Very large phosphorite deposits occur in Florida , Idaho , Morocco , and some middle eastern countries. Collapse breccia pipe deposits occur within vertical, circular solution collapse structures, formed by the dissolution of limestone by groundwater. Pipes are typically filled with down-dropped coarse fragments of limestone and overlying sediments and can be from 30 to 200 metres (100 to 660 ft) wide and up to 1,000 metres (3,300 ft) deep. Primary ore minerals are uraninite and pitchblende , which occur as cavity fills and coatings on quartz grains within permeable sandstone breccias within

1300-455: A type of rock consisting of repeated thin layers of iron oxides alternating with bands of iron-poor shale and chert . The banded iron formations were laid down in the time between 3,700  million years ago and 1,800  million years ago . Materials containing finely ground iron(III) oxides or oxide-hydroxides, such as ochre , have been used as yellow, red, and brown pigments since pre-historical times. They contribute as well to

1400-435: A very large coordination and organometallic chemistry : indeed, it was the discovery of an iron compound, ferrocene , that revolutionalized the latter field in the 1950s. Iron is sometimes considered as a prototype for the entire block of transition metals, due to its abundance and the immense role it has played in the technological progress of humanity. Its 26 electrons are arranged in the configuration [Ar]3d 4s , of which

1500-473: Is fissile (will support a neutron-mediated chain reaction ). Uranium, thorium , and one radioactive isotope of potassium ( K ) as well as their decay products are the main elements contributing to natural terrestrial radioactivity. Cosmogenic radionuclides are of less importance, but unlike the aforementioned primordial radionuclides , which date back to the formation of the planet and have since slowly decayed away, they are replenished at roughly

1600-630: Is also rarely found in basalts that have formed from magmas that have come into contact with carbon-rich sedimentary rocks, which have reduced the oxygen fugacity sufficiently for iron to crystallize. This is known as telluric iron and is described from a few localities, such as Disko Island in West Greenland, Yakutia in Russia and Bühl in Germany. Ferropericlase (Mg,Fe)O , a solid solution of periclase (MgO) and wüstite (FeO), makes up about 20% of

1700-401: Is another significant surficial deposit. Iron Iron is a chemical element ; it has the symbol Fe (from Latin ferrum  'iron') and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table . It is, by mass, the most common element on Earth , forming much of Earth's outer and inner core . It

1800-407: Is considered to be resistant to rust, due to its oxide layer. Iron forms various oxide and hydroxide compounds ; the most common are iron(II,III) oxide (Fe 3 O 4 ), and iron(III) oxide (Fe 2 O 3 ). Iron(II) oxide also exists, though it is unstable at room temperature. Despite their names, they are actually all non-stoichiometric compounds whose compositions may vary. These oxides are

1900-495: Is dissolution of uranium from the formation or nearby strata and the transport of this soluble uranium into the host unit. When the fluids change redox state, generally in contact with carbon -rich organic matter, uranium precipitates to form a 'front'. The roll front subtype deposits typically represent the largest of the sandstone-hosted uranium deposits and one of the largest uranium deposit types with an average of 21 million lb (9,500 t) U 3 O 8 . Included in this class are

2000-447: Is due to its abundant production during the runaway fusion and explosion of type Ia supernovae , which scatters the iron into space. Metallic or native iron is rarely found on the surface of the Earth because it tends to oxidize. However, both the Earth's inner and outer core , which together account for 35% of the mass of the whole Earth, are believed to consist largely of an iron alloy, possibly with nickel . Electric currents in

2100-560: Is especially concentrated along thin carbonaceous seams or carbon leaders. Strong regional scale alteration consists of pyrophyllite , chloritoid , muscovite , chlorite , quartz, rutile , and pyrite . The main elements associated with the uranium are gold and silver. Gold contents are much higher than in the Elliot Lake type with U:Au ranging between 5:1 and 500:1, which indicates that these gold-rich ores are essentially very low grade uranium deposits with gold. Sedimentological controls on

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2200-474: Is experimentally well defined for pressures less than 50 GPa. For greater pressures, published data (as of 2007) still varies by tens of gigapascals and over a thousand kelvin. Below its Curie point of 770 °C (1,420 °F; 1,040 K), α-iron changes from paramagnetic to ferromagnetic : the spins of the two unpaired electrons in each atom generally align with the spins of its neighbors, creating an overall magnetic field . This happens because

2300-482: Is far from ideal, as it does not consider that similar processes may form many deposit types, yet in a different geological setting. The following table groups the above deposit types based on their environment of deposition. Unconformity -type uranium deposits host high grades relative to other uranium deposits and include some of the largest and richest deposits known. They occur in close proximity to unconformities between relatively quartz -rich sandstones comprising

2400-443: Is in Earth's crust only amounts to about 5% of the overall mass of the crust and is thus only the fourth most abundant element in that layer (after oxygen , silicon , and aluminium ). Most of the iron in the crust is combined with various other elements to form many iron minerals . An important class is the iron oxide minerals such as hematite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), and siderite (FeCO 3 ), which are

2500-438: Is in the development stage at Patterson Lake (Triple R deposit) with an estimated mineral resource identified as; "Indicated Mineral Resources" estimated to total 2,291,000 tons at an average grade of 1.58% U 3 O 8 containing 79,610,000 pounds of U 3 O 8 . "Inferred Mineral Resources" are estimated to total 901,000 tons at an average grade of 1.30% U 3 O 8 containing 25,884,000 pounds of U 3 O 8 . The deposits of

2600-449: Is nonexistent to very weak at best, and the weak chlorite and sericite are believed to be mainly post-ore effects. Other post-depositional alteration includes pyritization , silicification , and alteration of titanium minerals. The most prominent geochemical associations with the uranium are thorium and titanium. This schematic model represents the original depositional setting. The Huronian underwent mild post-depositional folding during

2700-401: Is not like that of Mn with its weak, spin-forbidden d–d bands, because Fe has higher positive charge and is more polarizing, lowering the energy of its ligand-to-metal charge transfer absorptions. Thus, all the above complexes are rather strongly colored, with the single exception of the hexaquo ion – and even that has a spectrum dominated by charge transfer in the near ultraviolet region. On

2800-927: Is only naturally formed in supernova explosions. The primary uranium ore mineral is uraninite (UO 2 ) (previously known as pitchblende). A range of other uranium minerals can be found in various deposits. These include carnotite , tyuyamunite , torbernite and autunite . The davidite - brannerite - absite type uranium titanates, and the euxenite - fergusonite - samarskite group are other uranium minerals. A large variety of secondary uranium minerals are known, many of which are brilliantly coloured and fluorescent. The most common are gummite (a mixture of minerals), autunite (with calcium ), saleeite ( magnesium ) and torbernite (with copper ); and hydrated uranium silicates such as coffinite , uranophane (with calcium) and sklodowskite (magnesium). There are several themes of uranium ore deposit formation, which are caused by geological and chemical features of rocks and

2900-407: Is possible, but nonetheless the sequence does effectively end at Ni because conditions in stellar interiors cause the competition between photodisintegration and the alpha process to favor photodisintegration around Ni. This Ni, which has a half-life of about 6 days, is created in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in

3000-423: Is similar to that for roll front deposits except that the source of uranium may be in the watershed leading into a stream or in the bed load of the palaeochannel. This uranium is transported through groundwater and is deposited either at a reduced boundary or in ephemeral drainage systems such as those in deserts of Namibia and Australia; it is deposited in calcretised evaporation sites or even in saline lakes as

3100-548: Is somewhat different). Pieces of magnetite with natural permanent magnetization ( lodestones ) provided the earliest compasses for navigation. Particles of magnetite were extensively used in magnetic recording media such as core memories , magnetic tapes , floppies , and disks , until they were replaced by cobalt -based materials. Iron has four stable isotopes : Fe (5.845% of natural iron), Fe (91.754%), Fe (2.119%) and Fe (0.282%). Twenty-four artificial isotopes have also been created. Of these stable isotopes, only Fe has

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3200-442: Is such a strong oxidizing agent that it oxidizes ammonia to nitrogen (N 2 ) and water to oxygen: The pale-violet hex aquo complex [Fe(H 2 O) 6 ] is an acid such that above pH 0 it is fully hydrolyzed: As pH rises above 0 the above yellow hydrolyzed species form and as it rises above 2–3, reddish-brown hydrous iron(III) oxide precipitates out of solution. Although Fe has a d configuration, its absorption spectrum

3300-502: Is supposed to have an orthorhombic or a double hcp structure. (Confusingly, the term "β-iron" is sometimes also used to refer to α-iron above its Curie point, when it changes from being ferromagnetic to paramagnetic, even though its crystal structure has not changed. ) The inner core of the Earth is generally presumed to consist of an iron- nickel alloy with ε (or β) structure. The melting and boiling points of iron, along with its enthalpy of atomization , are lower than those of

3400-462: Is the fourth most abundant element in the Earth's crust , being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C (2,730 °F), about 500 °C (932 °F) higher than that required to smelt copper . Humans started to master that process in Eurasia during the 2nd millennium BC and

3500-583: Is the largest deposit of this class). These deposits are hosted in palaeochannels filled with Cenozoic sediments and sourced their uranium from uranium-rich Paleoproterozoic to Mesoproterozoic rocks of the Mount Painter Inlier and the Olary Domain of the Curnamona Province. Tectonic-lithologic controlled uranium deposits occur in sandstones adjacent to a permeable fault zone which cuts

3600-418: Is thus very important economically, and iron is the cheapest metal, with a price of a few dollars per kilogram or pound. Pristine and smooth pure iron surfaces are a mirror-like silvery-gray. Iron reacts readily with oxygen and water to produce brown-to-black hydrated iron oxides , commonly known as rust . Unlike the oxides of some other metals that form passivating layers, rust occupies more volume than

3700-590: Is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors . Globally, the distribution of uranium ore deposits is widespread on all continents, with the largest deposits found in Australia, Kazakhstan , and Canada. To date, high-grade deposits are only found in the Athabasca Basin region of Canada. Uranium deposits are generally classified based on host rocks, structural setting, and mineralogy of

3800-451: Is used as the traditional "blue" in blueprints . Iron is the first of the transition metals that cannot reach its group oxidation state of +8, although its heavier congeners ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low oxidation states similar to that of iron, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In

3900-437: Is used in chemical actinometry and along with its sodium salt undergoes photoreduction applied in old-style photographic processes. The dihydrate of iron(II) oxalate has a polymeric structure with co-planar oxalate ions bridging between iron centres with the water of crystallisation located forming the caps of each octahedron, as illustrated below. Iron(III) complexes are quite similar to those of chromium (III) with

4000-453: The Athabasca Basin in Canada, including the two largest high grade uranium deposits in the world, Cigar Lake with 217 million pounds (99,000 t) U 3 O 8 at an average grade of 18% and McArthur River with 324 million pounds (147,000 t) U 3 O 8 at an average grade of 17%. These deposits occur below, across and immediately above the unconformity. Additionally, another high grade discovery

4100-625: The Inkai deposit in Kazakhstan and the Smith Ranch deposit in Wyoming. Probably more significant than their larger size, roll front deposits have the advantage of being amenable to low cost in situ leach recovery. Typical characteristics: Basal channel deposits are often grouped with tabular or roll front deposits, depending on their unique characteristics. The model for formation of palaeochannel deposits

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4200-589: The McArthur River basin in the East Alligator Rivers region of the Northern Territory of Australia (including Jabiluka , Ranger , and Nabarlek ) are below the unconformity and are at the low-grade end of the unconformity deposit range but are still high grade compared to most uranium deposit types. There has been very little exploration in Australia to locate deeply concealed deposits lying above

4300-739: The Penokean orogeny around 1.9 billion years. The main regional structure is the Quirke syncline along the margins of which the majority of the known deposits are situated. Ore bodies range from subhorizontal to steeply dipping . Only one iron oxide copper gold ore deposit is known to contain economically significant quantities of uranium. Olympic Dam in South Australia is the world's largest resource of low-grade uranium and accounts for about 66% of Australia's reserves plus resources. Uranium occurs with copper, gold, silver, and rare-earth elements in

4400-537: The Variscan orogeny , extension took place and hydrothermal fluids overprinted fine grained materials in shear zones with a sulfide-chlorite alteration. Fluids from the overlying sediments entered the basement mobilising uranium and while uprising on the shear zone, the chlorite-pyrite material caused precipitation of uranium minerals in form of coffinite, pitchblende and U-Zr-silicates. This initial mineralisation event took place at about 277 million to 264 million years. During

4500-432: The supernova remnant gas cloud, first to radioactive Co, and then to stable Fe. As such, iron is the most abundant element in the core of red giants , and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth . It is also very common in the universe, relative to other stable metals of approximately the same atomic weight . Iron is the sixth most abundant element in

4600-488: The trans - chlorohydridobis(bis-1,2-(diphenylphosphino)ethane)iron(II) complex is used as a starting material for compounds with the Fe( dppe ) 2 moiety . The ferrioxalate ion with three oxalate ligands displays helical chirality with its two non-superposable geometries labelled Λ (lambda) for the left-handed screw axis and Δ (delta) for the right-handed screw axis, in line with IUPAC conventions. Potassium ferrioxalate

4700-466: The universe , and the most common refractory element. Although a further tiny energy gain could be extracted by synthesizing Ni , which has a marginally higher binding energy than Fe, conditions in stars are unsuitable for this process. Element production in supernovas greatly favor iron over nickel, and in any case, Fe still has a lower mass per nucleon than Ni due to its higher fraction of lighter protons. Hence, elements heavier than iron require

4800-570: The 3d and 4s electrons are relatively close in energy, and thus a number of electrons can be ionized. Iron forms compounds mainly in the oxidation states +2 ( iron(II) , "ferrous") and +3 ( iron(III) , "ferric"). Iron also occurs in higher oxidation states , e.g., the purple potassium ferrate (K 2 FeO 4 ), which contains iron in its +6 oxidation state. The anion [FeO 4 ] with iron in its +7 oxidation state, along with an iron(V)-peroxo isomer, has been detected by infrared spectroscopy at 4 K after cocondensation of laser-ablated Fe atoms with

4900-594: The Czech Republic. Also they are closely related to the granites, the mineralization is much younger with a time gap between granite formation and mineralisation of 20 million years. The initial uranium mineralisation consists of quartz, carbonate , fluorite and pitchblende. Remobilisation of uranium occurred at later stages producing polymetal veins containing silver, cobalt , nickel , arsenic and other elements. Large deposits of this type can contain more than 1,000 individual mineralized veins. However, only 5 to 12% of

5000-589: The Earth's surface. Items made of cold-worked meteoritic iron have been found in various archaeological sites dating from a time when iron smelting had not yet been developed; and the Inuit in Greenland have been reported to use iron from the Cape York meteorite for tools and hunting weapons. About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Native iron

5100-628: The Huronian deposits appear to be much stronger than in the Witwatersrand deposits. Ores grade from uranium through thorium to titanium -rich with decreasing pebble size and increasing distance from their source. While evidence of post- diagenetic remobilization has been identified, these effects appear far subordinate to the sedimentological controls. Ore consists of uraninite with lesser brannerite and thucholite. These occur in thin beds exhibiting graded bedding reminiscent of placer sorting. Alteration

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5200-480: The Huronian deposits are situated at the base of the sequence, whereas the mineralized horizons at Witwatersand are arguably along tectonized intraformational unconformities. Uranium minerals were derived from uraniferous pegmatites in the sediment source areas. These deposits are restricted to the Archean and early Paleoproterozoic and do not occur in sediments younger than about 2,200 million years when oxygen levels in

5300-598: The Precambrian to the Cenozoic, but because of the shallow levels at which they form, preservation favors younger age deposits. Some of the more important deposits or districts are Streltsovskoye, Russia ; Dornod, Mongolia ; and McDermitt, Nevada . The average deposit size is rather small with grades of 0.02% to 0.2% U 3 O 8 . These deposits make up only a small proportion of the world's uranium resources. The only volcanic hosted deposits currently being exploited are those of

5400-581: The Streltsovkoye district of eastern Siberia . This is in fact not a single stand-alone deposit, but 18 individual deposits occurring within the Streltsovsk caldera complex. Nevertheless, the average size of these deposits is far greater than the average volcanic type. Surficial deposits are broadly defined as Tertiary to Holocene near-surface uranium concentrations in sediments or soils. Mineralization in calcrete ( calcium and magnesium carbonates ) are

5500-908: The Triassic a further mineralisation event took place relocating uranium into quartz-carbonate-uranium veins. Another example of this mineralisation style is the Shinkolobwe deposit in Congo containing about 30,000 t of uranium. Intrusive deposits make up a large proportion of the world's uranium resources. Included in this type are those associated with intrusive rocks including alaskite , granite , pegmatite and monzonites . Major world deposits include Rossing ( Namibia ), Ilimaussaq intrusive complex ( Greenland ) and Palabora ( South Africa ). Marine sedimentary phosphorite deposits can contain low grade concentrations of uranium, up to 0.01–0.015% U 3 O 8 , within fluorite or apatite . These deposits can have

5600-595: The Witwatersrand deposits, ores are found along unconformities, shale and siltstone beds, and carbonaceous seams. The West Rand Group of sediments tend to host the most uranium within the Witwatersrand Supergroup. The uranium rich Dominion Reef is located at the base of the West Rand Supergroup. The Vaal Reef is the most uranium rich reef of the Central Rand Group of sediments. Structural controls on

5700-601: The atmosphere reached a critical level, making simple uranium oxides no longer stable in near-surface environments. Quartz pebble conglomerate uranium deposits are typically low grade but characterized by high tonnages. The Huronian deposits generally contain higher grades (0.15% U 3 O 8 ) and greater resources (as shown by the Denison and Quirke mines), however some of the Witwatersand gold deposits also contain sizeable low grade (0.01% U 3 O 8 ) uranium resources. In

5800-611: The basal portion of relatively undeformed sedimentary basins and deformed metamorphic basement rocks . These sedimentary basins are typically of Proterozoic age, however some Phanerozoic examples exist. Phanerozoic unconformity-related deposits occur in Proterozoic metasediments below an unconformity at the base of overlying Phanerozoic sandstone. These deposits are small and low-grade (e.g., Bertholene and Aveyron deposits in France). The highest grade uranium deposits are found in

5900-450: The brown deposits present in a sizeable number of streams. Due to its electronic structure, iron has a very large coordination and organometallic chemistry. Many coordination compounds of iron are known. A typical six-coordinate anion is hexachloroferrate(III), [FeCl 6 ] , found in the mixed salt tetrakis(methylammonium) hexachloroferrate(III) chloride . Complexes with multiple bidentate ligands have geometric isomers . For example,

6000-683: The color of various rocks and clays , including entire geological formations like the Painted Hills in Oregon and the Buntsandstein ("colored sandstone", British Bunter ). Through Eisensandstein (a jurassic 'iron sandstone', e.g. from Donzdorf in Germany) and Bath stone in the UK, iron compounds are responsible for the yellowish color of many historical buildings and sculptures. The proverbial red color of

6100-464: The cores of the Earth and other planets. Above approximately 10 GPa and temperatures of a few hundred kelvin or less, α-iron changes into another hexagonal close-packed (hcp) structure, which is also known as ε-iron . The higher-temperature γ-phase also changes into ε-iron, but does so at higher pressure. Some controversial experimental evidence exists for a stable β phase at pressures above 50 GPa and temperatures of at least 1500 K. It

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6200-554: The deposit. The most widely used classification scheme was developed by the International Atomic Energy Agency and subdivides deposits into 15 categories. Uranium is a silvery-gray, weakly radioactive metallic chemical element . It has the chemical symbol U and atomic number 92. The most common isotopes in natural uranium are U (99.274%) and U (0.711%). All uranium isotopes present in natural uranium are radioactive and fissionable , and U

6300-521: The direction of groundwater flow, but on a small scale the ore zones may cut across sedimentary features of the host sandstone. Deposits of this nature commonly occur within palaeochannels cut in the underlying basement rocks. Tabular sandstone uranium deposits contain many of the highest grades of the sandstone class, however the average deposit size is very small. Roll-front uranium deposits are generally hosted within permeable and porous sandstones or conglomerates . The mechanism for deposit formation

6400-401: The domains in the new positions, so that the effect persists even after the external field is removed – thus turning the iron object into a (permanent) magnet . Similar behavior is exhibited by some iron compounds, such as the ferrites including the mineral magnetite , a crystalline form of the mixed iron(II,III) oxide Fe 3 O 4 (although the atomic-scale mechanism, ferrimagnetism ,

6500-479: The earlier 3d elements from scandium to chromium , showing the lessened contribution of the 3d electrons to metallic bonding as they are attracted more and more into the inert core by the nucleus; however, they are higher than the values for the previous element manganese because that element has a half-filled 3d sub-shell and consequently its d-electrons are not easily delocalized. This same trend appears for ruthenium but not osmium . The melting point of iron

6600-405: The element uranium. The basic themes of uranium ore genesis are host mineralogy, reduction-oxidation potential , and porosity . Uranium is a highly soluble and radioactive heavy metal . It can be easily dissolved, transported and precipitated within groundwater by subtle changes in oxidation conditions. Uranium does not usually form very insoluble mineral species, which is a further factor in

6700-406: The exception of iron(III)'s preference for O -donor instead of N -donor ligands. The latter tend to be rather more unstable than iron(II) complexes and often dissociate in water. Many Fe–O complexes show intense colors and are used as tests for phenols or enols . For example, in the ferric chloride test , used to determine the presence of phenols, iron(III) chloride reacts with a phenol to form

6800-462: The global stock of iron in use in society is 2,200 kg per capita. More-developed countries differ in this respect from less-developed countries (7,000–14,000 vs 2,000 kg per capita). Ocean science demonstrated the role of the iron in the ancient seas in both marine biota and climate. Iron shows the characteristic chemical properties of the transition metals , namely the ability to form variable oxidation states differing by steps of one and

6900-487: The largest of the surficial deposits. They are interbedded with Tertiary sand and clay, which are usually cemented by calcium and magnesium carbonates. Surficial deposits also occur in peat bogs , karst caverns and soils. Surficial deposits account for approximately 4% of world uranium resources. The Yeelirrie deposit is by far the world's largest surficial deposit, averaging 0.15% U 3 O 8 . Langer Heinrich in Namibia

7000-547: The late phase of magmatic activity when hot fluids derived from the magma precipitate uranium on cracks within the newly formed granite. Such mineralisation contributed much to the uranium production of France. Veins hosted by metasedimentary units in the exocontact of granites are the most important sources of uranium mineralisation in central Europe including the world class deposits Schneeberg-Schlema-Alberoda in Germany (96,000 t uranium content) as well as Pribram (50,000 t uranium content) and Jachymov (~10,000 t uranium content) in

7100-449: The liquid outer core are believed to be the origin of the Earth's magnetic field . The other terrestrial planets ( Mercury , Venus , and Mars ) as well as the Moon are believed to have a metallic core consisting mostly of iron. The M-type asteroids are also believed to be partly or mostly made of metallic iron alloy. The rare iron meteorites are the main form of natural metallic iron on

7200-446: The literature, this mineral phase of the lower mantle is also often called magnesiowüstite. Silicate perovskite may form up to 93% of the lower mantle, and the magnesium iron form, (Mg,Fe)SiO 3 , is considered to be the most abundant mineral in the Earth, making up 38% of its volume. While iron is the most abundant element on Earth, most of this iron is concentrated in the inner and outer cores. The fraction of iron that

7300-407: The major ores of iron . Many igneous rocks also contain the sulfide minerals pyrrhotite and pentlandite . During weathering , iron tends to leach from sulfide deposits as the sulfate and from silicate deposits as the bicarbonate. Both of these are oxidized in aqueous solution and precipitate in even mildly elevated pH as iron(III) oxide . Large deposits of iron are banded iron formations ,

7400-775: The metal and thus flakes off, exposing more fresh surfaces for corrosion. Chemically, the most common oxidation states of iron are iron(II) and iron(III) . Iron shares many properties of other transition metals, including the other group 8 elements , ruthenium and osmium . Iron forms compounds in a wide range of oxidation states , −4 to +7. Iron also forms many coordination compounds ; some of them, such as ferrocene , ferrioxalate , and Prussian blue have substantial industrial, medical, or research applications. The body of an adult human contains about 4 grams (0.005% body weight) of iron, mostly in hemoglobin and myoglobin . These two proteins play essential roles in oxygen transport by blood and oxygen storage in muscles . To maintain

7500-606: The meteorites Semarkona and Chervony Kut, a correlation between the concentration of Ni, the granddaughter of Fe, and the abundance of the stable iron isotopes provided evidence for the existence of Fe at the time of formation of the Solar System . Possibly the energy released by the decay of Fe, along with that released by Al , contributed to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of Ni present in extraterrestrial material may bring further insight into

7600-559: The necessary levels, human iron metabolism requires a minimum of iron in the diet. Iron is also the metal at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals. At least four allotropes of iron (differing atom arrangements in the solid) are known, conventionally denoted α , γ , δ , and ε . The first three forms are observed at ordinary pressures. As molten iron cools past its freezing point of 1538 °C, it crystallizes into its δ allotrope, which has

7700-436: The orbitals of those two electrons (d z and d x − y ) do not point toward neighboring atoms in the lattice, and therefore are not involved in metallic bonding. In the absence of an external source of magnetic field, the atoms get spontaneously partitioned into magnetic domains , about 10 micrometers across, such that the atoms in each domain have parallel spins, but some domains have other orientations. Thus

7800-533: The origin and early history of the Solar System . The most abundant iron isotope Fe is of particular interest to nuclear scientists because it represents the most common endpoint of nucleosynthesis . Since Ni (14 alpha particles ) is easily produced from lighter nuclei in the alpha process in nuclear reactions in supernovae (see silicon burning process ), it is the endpoint of fusion chains inside extremely massive stars . Although adding more alpha particles

7900-444: The other hand, the pale green iron(II) hexaquo ion [Fe(H 2 O) 6 ] does not undergo appreciable hydrolysis. Carbon dioxide is not evolved when carbonate anions are added, which instead results in white iron(II) carbonate being precipitated out. In excess carbon dioxide this forms the slightly soluble bicarbonate, which occurs commonly in groundwater, but it oxidises quickly in air to form iron(III) oxide that accounts for

8000-581: The oxidizing power of Fe and the high reducing power of I : Ferric iodide, a black solid, is not stable in ordinary conditions, but can be prepared through the reaction of iron pentacarbonyl with iodine and carbon monoxide in the presence of hexane and light at the temperature of −20 °C, with oxygen and water excluded. Complexes of ferric iodide with some soft bases are known to be stable compounds. The standard reduction potentials in acidic aqueous solution for some common iron ions are given below: The red-purple tetrahedral ferrate (VI) anion

8100-497: The past work on isotopic composition of iron has focused on the nucleosynthesis of Fe through studies of meteorites and ore formation. In the last decade, advances in mass spectrometry have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work is driven by the Earth and planetary science communities, although applications to biological and industrial systems are emerging. In phases of

8200-682: The pipe. Resources within individual pipes can range up to 2500 tonnes U 3 O 8 at an average grade of between 0.3 and 1.0% U 3 O 8 . The best known examples of this deposit type are in the Arizona breccia pipe uranium mineralization in the US, where several of these deposits have been mined. Volcanic deposits occur in felsic to intermediate volcanic to volcaniclastic rocks and associated caldera subsidence structures, comagmatic intrusions, ring dykes and diatremes . Mineralization occurs either as structurally controlled veins and breccias discordant to

8300-414: The principal ores for the production of iron (see bloomery and blast furnace). They are also used in the production of ferrites , useful magnetic storage media in computers, and pigments. The best known sulfide is iron pyrite (FeS 2 ), also known as fool's gold owing to its golden luster. It is not an iron(IV) compound, but is actually an iron(II) polysulfide containing Fe and S 2 ions in

8400-423: The quartz-hematite breccias. The breccias in the area host a low grade resource of about 31,400 t U 3 O 8 at 615 ppm in average. Vein deposits play a special role in the history of uranium: the term "pitchblende" (" pechblende ") originates from German vein deposits when they were mined for silver in the 16th century. Franz Ernst Brückmann made the first mineralogical description of the mineral in 1727, and

8500-614: The raw material for nuclear weapons in the Soviet military arsenal. The mining operations are now under the control of the Navoi Mining and Metallurgy Combinat (NMMC), which continues to mine and process uranium using in-situ leach processes. The company also produces gold by the same process. Aeroflot Flight 5143 crashed near Uchkuduk on July 10, 1985. This was the deadliest air disaster in Uzbek and Soviet history. The Uzbek group Yalla made

8600-464: The regional scale are normal faults while on the deposit scale are bedding parallel shears and thrusts. Textural evidence indicates that the uranium and gold have been remobilized to their current sites; however the debate continues if the original deposition was detrital or was entirely hydrothermal, or alternatively related to high grade diagenesis . Uranium minerals are typically uraninite with lesser uranothorite, brannerite, and coffinite. The uranium

8700-404: The same rate they decay by the bombardment of Earth with cosmic rays . Uranium has the highest atomic weight of the naturally occurring elements and is approximately 70% denser than lead , but it is not as dense as tungsten , gold , platinum , iridium , or osmium . It is always found combined with other elements. Along with all elements having atomic weights higher than that of iron , it

8800-501: The sandstone/mudstone sequence. Mineralisation forms tongue-shaped ore zones along the permeable sandstone layers adjacent to the fault. Often there are mineralised zones 'stacked' vertically on top of each other within sandstone units adjacent to the fault zone. Quartz pebble conglomerate hosted uranium deposits are of historical significance as the major source of primary production for several decades after World War II . This type of deposit has been identified in eight localities around

8900-437: The second half of the 3d transition series, vertical similarities down the groups compete with the horizontal similarities of iron with its neighbors cobalt and nickel in the periodic table, which are also ferromagnetic at room temperature and share similar chemistry. As such, iron, cobalt, and nickel are sometimes grouped together as the iron triad . Unlike many other metals, iron does not form amalgams with mercury . As

9000-632: The sedimentary sequence and often occur immediately above and below the mineralised horizon. Uranium is mobile under oxidising conditions and precipitates under reducing conditions, and thus the presence of a reducing environment is essential for the formation of uranium deposits in sandstone. Primary mineralization consists of pitchblende and coffinite, with weathering producing secondary mineralization. Sandstone deposits constitute about 18% of world uranium resources. Orebodies of this type are commonly low to medium grade (0.05–0.4% U 3 O 8 ) and individual orebodies are small to medium in size (ranging up to

9100-507: The stratigraphy and less commonly as stratabound mineralization either in extrusive rocks or permeable sedimentary facies . Mineralization may be primary, that is magmatic-related or as secondary mineralization due to leaching, remobilization and re-precipitation. The principal uranium mineral in volcanic deposits is pitchblende, which is usually associated with molybdenite and minor amounts of lead, tin and tungsten mineralization. Volcanic hosted uranium deposits occur in host rocks spanning

9200-547: The surface of Mars is derived from an iron oxide-rich regolith . Significant amounts of iron occur in the iron sulfide mineral pyrite (FeS 2 ), but it is difficult to extract iron from it and it is therefore not exploited. In fact, iron is so common that production generally focuses only on ores with very high quantities of it. According to the International Resource Panel 's Metal Stocks in Society report ,

9300-471: The unconformity similar to those in Canada. It is possible that very high grade deposits occur in the sandstones above the unconformity in the Alligator Rivers/ Arnhem Land area. Sandstone deposits are contained within medium to coarse-grained sandstones deposited in a continental fluvial or marginal marine sedimentary environment . Impermeable shale or mudstone units are interbedded in

9400-529: The use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age . In the modern world , iron alloys, such as steel , stainless steel , cast iron and special steels , are by far the most common industrial metals, due to their mechanical properties and low cost. The iron and steel industry

9500-546: The vein areas carry mineralization and although massive lenses of pitchblende can occur, the overall ore grade is only about 0.1% uranium. The Bohemian Massif contains shear zone hosted uranium deposits with the most important one being Rozna-Olsi in Moravia northwest of Brno . Rozna is currently the only operating uranium mine in central Europe with a total uranium content of 23,000 t and an average grade of 0.24%. The formation of this mineralisation occurred in several stages. After

9600-929: The vein deposit Jachymov in the Czech Republic became the type locality for uraninite. In 1789 German chemist Martin Heinrich Klaproth discovered the element uranium in a sample of pitchblende from the Johanngeorgenstadt vein deposit. The first industrial production of uranium was made from the Jachymov deposit, and Marie and Pierre Curie used the tailings of the mine for their discovery of polonium and radium . Vein deposits consist of uranium minerals filling in cavities such as cracks, veins, fractures, breccias, and stockworks associated with steeply dipping fault systems. There are three major subtypes of vein style uranium mineralisation: Intragranitic veins form in

9700-455: The volume of the lower mantle of the Earth, which makes it the second most abundant mineral phase in that region after silicate perovskite (Mg,Fe)SiO 3 ; it also is the major host for iron in the lower mantle. At the bottom of the transition zone of the mantle, the reaction γ- (Mg,Fe) 2 [SiO 4 ] ↔ (Mg,Fe)[SiO 3 ] + (Mg,Fe)O transforms γ-olivine into a mixture of silicate perovskite and ferropericlase and vice versa. In

9800-549: The water evaporates. Some particularly rich uranium deposits are formed in palaeochannels which are filled in the lower parts by lignite or brown coal , which acts as a particularly efficient reductive trap for uranium. Sometimes, elements such as scandium , gold and silver may be concentrated within these lignite-hosted uranium deposits. The Frome Embayment in South Australia hosts several deposits of this type including Honeymoon , Oban, Beverley and Four-Mile (which

9900-762: The wide variety of geological conditions and places in which uranium mineralization may accumulate. Uranium is an incompatible element within magmas , and as such it tends to become accumulated within highly fractionated and evolved granite melts, particularly alkaline examples. These melts tend to become highly enriched in uranium, thorium and potassium, and may in turn create internal pegmatites or hydrothermal systems into which uranium may dissolve. The International Atomic Energy Agency (IAEA) assigns uranium deposits to 15 main categories of deposit types, according to their geological setting and genesis of mineralization, arranged according to their approximate economic significance. The IAEA classification scheme works well but

10000-812: The world. The most significant deposits are in the Huronian Supergroup in Elliot Lake , Ontario , Canada and in the Witwatersrand Supergroup of South Africa . These deposits make up approximately 13% of the world's uranium resources. Quartz pebble conglomerate hosted uranium deposits formed from the transport and deposition of uraninite in a fluvial sedimentary environment and are defined as stratiform and stratabound placer deposits . Host rocks are typically submature to supermature, polymictic conglomerates and sandstones deposited in alluvial fan and braided stream environments. The host conglomerates of

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