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93-656: Oklo is the only location where this phenomenon is known to have occurred, and consists of 16 sites with patches of centimeter-sized ore layers . There, self-sustaining nuclear fission reactions are thought to have taken place approximately 1.7 billion years ago, during the Statherian period of the Paleoproterozoic . Fission in the ore at Oklo continued off and on for a few hundred thousand years and probably never exceeded 100 kW of thermal power. Life on Earth at this time consisted largely of sea-bound algae and

186-483: A U concentration as low as 0.44% (almost 40% below the normal value). Subsequent examination of isotopes of fission products such as neodymium and ruthenium also showed anomalies, as described in more detail below. However, the trace radioisotope U did not deviate significantly in its concentration from other natural samples. Both depleted uranium and reprocessed uranium will usually have U concentrations significantly different from

279-511: A 3-hour cycle. Xenon-135 is the strongest known neutron poison. However, it is not produced directly in appreciable amounts but rather as a decay product of iodine-135 (or one of its parent nuclides ). Xenon-135 itself is unstable and decays to caesium-135 if not allowed to absorb neutrons. While caesium-135 is relatively long lived, all caesium-135 produced by the Oklo reactor has since decayed further to stable barium-135 . Meanwhile, xenon-136,

372-487: A by-product from processing of nickel , copper , and platinum metal ore. During electrorefining of copper and nickel, noble metals such as silver, gold, and the platinum group metals precipitate as anode mud , the feedstock for the extraction. The metals are converted to ionized solutes by any of several methods, depending on the composition of the feedstock. One representative method is fusion with sodium peroxide followed by dissolution in aqua regia , and solution in

465-458: A centimeter over several million years. The average diameter of a polymetallic nodule is between 3 and 10 cm (1 and 4 in) in diameter and are characterized by enrichment in iron, manganese, heavy metals , and rare earth element content when compared to the Earth's crust and surrounding sediment. The proposed mining of these nodules via remotely operated ocean floor trawling robots has raised

558-541: A chain reaction. Fission of uranium normally produces five known isotopes of the fission-product gas xenon ; all five have been found trapped in the remnants of the natural reactor, in varying concentrations. The concentrations of xenon isotopes, found trapped in mineral formations 2 billion years later, make it possible to calculate the specific time intervals of reactor operation: approximately 30 minutes of criticality followed by 2 hours and 30 minutes of cooling down (exponentially decreasing residual decay heat ) to complete

651-744: A different isotope signature. The level of Ru in the fission product mixture is low because fission produces neutron rich isotopes which subsequently beta decay and Ru would only be produced in appreciable quantities by double beta decay of the very long-lived (half life 7.1 × 10 years) molybdenum isotope Mo . On the timescale of when the reactors were in operation, very little (about 0.17  ppb ) decay to Ru will have occurred. Other pathways of Ru production like neutron capture in Ru or Tc (quickly followed by beta decay) can only have occurred during high neutron flux and thus ceased when

744-409: A different isotopic composition to that of natural neodymium: the latter contains 27% Nd , while that of Oklo contains less than 6%. The Nd is not produced by fission; the ore contains both fission-produced and natural neodymium. From this Nd content, we can subtract the natural neodymium and gain access to the isotopic composition of neodymium produced by

837-421: A direct result of metamorphism. These are the leading source of copper ore. Porphyry copper deposits form along convergent boundaries and are thought to originate from the partial melting of subducted oceanic plates and subsequent concentration of Cu, driven by oxidation. These are large, round, disseminated deposits containing on average 0.8% copper by weight. Hydrothermal Hydrothermal deposits are

930-449: A large source of ore. They form as a result of the precipitation of dissolved ore constituents out of fluids. Laterites form from the weathering of highly mafic rock near the equator. They can form in as little as one million years and are a source of iron (Fe), manganese (Mn), and aluminum (Al). They may also be a source of nickel and cobalt when the parent rock is enriched in these elements. Banded iron formations (BIFs) are

1023-520: A long-standing controversy between Berzelius and Osann about the composition of the residues. As Osann was not able to repeat his isolation of ruthenium, he eventually relinquished his claims. The name "ruthenium" was chosen by Osann because the analysed samples stemmed from the Ural Mountains in Russia. In 1844, Karl Ernst Claus , a Russian scientist of Baltic German descent, showed that

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1116-503: A major use of ruthenium. The ruthenium plate is applied to the electrical contact and electrode base metal by electroplating or sputtering . Ruthenium dioxide with lead and bismuth ruthenates are used in thick-film chip resistors. These two electronic applications account for 50% of the ruthenium consumption. Ruthenium is seldom alloyed with metals outside the platinum group, where small quantities improve some properties. The added corrosion resistance in titanium alloys led to

1209-419: A minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst . A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks . Ruthenium

1302-430: A mixture of chlorine with hydrochloric acid . Osmium , ruthenium, rhodium , and iridium are insoluble in aqua regia and readily precipitate, leaving the other metals in solution. Rhodium is separated from the residue by treatment with molten sodium bisulfate. The insoluble residue, containing Ru, Os, and Ir is treated with sodium oxide, in which Ir is insoluble, producing dissolved Ru and Os salts. After oxidation to

1395-427: A much higher Ru concentration than otherwise naturally occurring (27–30% vs. 12.7%). This anomaly could be explained by the decay of Tc to Ru . In the bar chart, the normal natural isotope signature of ruthenium is compared with that for fission product ruthenium which is the result of the fission of U with thermal neutrons. The fission ruthenium has

1488-447: A negative void coefficient of reactivity, something employed as a safety mechanism in human-made light water reactors . After cooling of the mineral deposit, the water returned, and the reaction restarted, completing a full cycle every 3 hours. The fission reaction cycles continued for hundreds of thousands of years and ended when the ever-decreasing fissile materials, coupled with the build-up of neutron poisons , no longer could sustain

1581-644: A number of ecological concerns. The extraction of ore deposits generally follows these steps. Progression from stages 1–3 will see a continuous disqualification of potential ore bodies as more information is obtained on their viability: With rates of ore discovery in a steady decline since the mid 20th century, it is thought that most surface level, easily accessible sources have been exhausted. This means progressively lower grade deposits must be turned to, and new methods of extraction must be developed. Some ores contain heavy metals , toxins, radioactive isotopes and other potentially negative compounds which may pose

1674-824: A risk to the environment or health. The exact effects an ore and its tailings have is dependent on the minerals present. Tailings of particular concern are those of older mines, as containment and remediation methods in the past were next to non-existent, leading to high levels of leaching into the surrounding environment. Mercury and arsenic are two ore related elements of particular concern. Additional elements found in ore which may have adverse health affects in organisms include iron, lead, uranium, zinc, silicon, titanium, sulfur, nitrogen, platinum, and chromium. Exposure to these elements may result in respiratory and cardiovascular problems and neurological issues. These are of particular danger to aquatic life if dissolved in water. Ores such as those of sulphide minerals may severely increase

1767-513: A single mineral, but it is mixed with other valuable minerals and with unwanted or valueless rocks and minerals. The part of an ore that is not economically desirable and that cannot be avoided in mining is known as gangue . The valuable ore minerals are separated from the gangue minerals by froth flotation , gravity concentration, electric or magnetic methods, and other operations known collectively as mineral processing or ore dressing . Mineral processing consists of first liberation, to free

1860-552: A sizeable portion of international trade in raw materials both in value and volume. This is because the worldwide distribution of ores is unequal and dislocated from locations of peak demand and from smelting infrastructure. Most base metals (copper, lead, zinc, nickel) are traded internationally on the London Metal Exchange , with smaller stockpiles and metals exchanges monitored by the COMEX and NYMEX exchanges in

1953-401: A third of fission events over the course of normal burnup in modern human-made light water reactors ), then fission product yields amount to roughly 129 kilograms (284 lb) of technetium-99 (since decayed to ruthenium-99), 108 kilograms (238 lb) of zirconium-93 (since decayed to niobium -93), 198 kilograms (437 lb) of caesium-135 (since decayed to barium-135, but the real value

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2046-471: A trend that continues to this day – naming an element after a country. Approximately 30.9 tonnes of ruthenium were consumed in 2016, 13.8 of them in electrical applications, 7.7 in catalysis, and 4.6 in electrochemistry. Because it hardens platinum and palladium alloys, ruthenium is used in electrical contacts , where a thin film is sufficient to achieve the desired durability. With its similar properties to and lower cost than rhodium, electric contacts are

2139-486: A variety of geological processes generally referred to as ore genesis and can be classified based on their deposit type. Ore is extracted from the earth through mining and treated or refined , often via smelting , to extract the valuable metals or minerals. Some ores, depending on their composition, may pose threats to health or surrounding ecosystems. The word ore is of Anglo-Saxon origin, meaning lump of metal . In most cases, an ore does not consist entirely of

2232-687: Is a biological stain used to stain polyanionic molecules such as pectin and nucleic acids for light microscopy and electron microscopy . The beta-decaying isotope 106 of ruthenium is used in radiotherapy of eye tumors, mainly malignant melanomas of the uvea . Ruthenium-centered complexes are being researched for possible anticancer properties. Compared with platinum complexes, those of ruthenium show greater resistance to hydrolysis and more selective action on tumors. Ruthenium tetroxide exposes latent fingerprints by reacting on contact with fatty oils or fats with sebaceous contaminants and producing brown/black ruthenium dioxide pigment. Electronics

2325-483: Is a mineral deposit occurring in high enough concentration to be economically viable. An ore deposit is one occurrence of a particular ore type. Most ore deposits are named according to their location, or after a discoverer (e.g. the Kambalda nickel shoots are named after drillers), or after some whimsy, a historical figure, a prominent person, a city or town from which the owner came, something from mythology (such as

2418-453: Is a rare transition metal belonging to the platinum group of the periodic table . Like the other metals of the platinum group, ruthenium is unreactive to most chemicals. Karl Ernst Claus , a Russian scientist of Baltic-German ancestry, discovered the element in 1844 at Kazan State University and named it in honor of Russia , using the Latin name Ruthenia . Ruthenium is usually found as

2511-431: Is a very rare mineral (Ir replaces part of Ru in its structure). Ruthenium has a relatively high fission product yield in nuclear fission; and given that its most long-lived radioisotope has a half life of "only" around a year, there are often proposals to recover ruthenium in a new kind of nuclear reprocessing from spent fuel . An unusual ruthenium deposit can also be found at the natural nuclear fission reactor that

2604-444: Is black. Of the dihalides, difluoride is not known, dichloride is brown, dibromide is black, and diiodide is blue. The only known oxyhalide is the pale green ruthenium(VI) oxyfluoride, RuOF 4 . Ruthenium forms a variety of coordination complexes. Examples are the many pentaammine derivatives [Ru(NH 3 ) 5 L] that often exist for both Ru(II) and Ru(III). Derivatives of bipyridine and terpyridine are numerous, best known being

2697-410: Is considered alluvial if formed via river, colluvial if by gravity, and eluvial when close to their parent rock. Polymetallic nodules , also called manganese nodules, are mineral concretions on the sea floor formed of concentric layers of iron and manganese hydroxides around a core. They are formed by a combination of diagenetic and sedimentary precipitation at the estimated rate of about

2790-494: Is contained in spent nuclear fuel , both as a direct fission product and as a product of neutron absorption by long-lived fission product Tc . After allowing the unstable isotopes of ruthenium to decay, chemical extraction could yield ruthenium for use in all applications of ruthenium. Ruthenium can also be produced by deliberate nuclear transmutation from Tc . Given its relatively long half life, high fission product yield and high chemical mobility in

2883-610: Is found in about 100  parts per trillion in the Earth's crust, making it the 78th most abundant element . It is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury , Ontario , Canada, and in pyroxenite deposits in South Africa . The native form of ruthenium

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2976-518: Is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America . Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario , and in pyroxenite deposits in South Africa . Ruthenium, a polyvalent hard white metal, is a member of the platinum group and is in group 8 of the periodic table: Whereas all other group 8 elements have two electrons in

3069-496: Is known to be superconductive at temperatures below 10.6 K . Ruthenium is the only 4d transition metal that can assume the group oxidation state +8, and even then it is less stable there than the heavier congener osmium: this is the first group from the left of the table where the second and third-row transition metals display notable differences in chemical behavior. Like iron but unlike osmium, ruthenium can form aqueous cations in its lower oxidation states of +2 and +3. Ruthenium

3162-499: Is mostly used as an intermediate in the purification of ruthenium from ores and radiowastes. Dipotassium ruthenate (K 2 RuO 4 , +6) and potassium perruthenate (KRuO 4 , +7) are also known. Unlike osmium tetroxide, ruthenium tetroxide is less stable, is strong enough as an oxidising agent to oxidise dilute hydrochloric acid and organic solvents like ethanol at room temperature, and is easily reduced to ruthenate ( RuO 4 ) in aqueous alkaline solutions; it decomposes to form

3255-464: Is naturally present in the rocks of the earth, and the abundance of fissile U was at least 3% or higher at all times prior to reactor startup. Uranium is soluble in water only in the presence of oxygen . Therefore, increasing oxygen levels during the aging of the Earth may have allowed uranium to be dissolved and transported with groundwater to places where a high enough concentration could accumulate to form rich uranium ore bodies. Without

3348-481: Is not as far off the trend in the 4d series as manganese in the 3d transition series.) Unlike the lighter congener iron, ruthenium is paramagnetic at room temperature, as iron also is above its Curie point . The reduction potentials in acidic aqueous solution for some common ruthenium species are shown below: Naturally occurring ruthenium is composed of seven stable isotopes . Additionally, 34 radioactive isotopes have been discovered. Of these radioisotopes ,

3441-500: Is not attacked by acids (even aqua regia ) but is attacked by sodium hypochlorite at room temperature, and halogens at high temperatures. Ruthenium is most readily attacked by oxidizing agents. Small amounts of ruthenium can increase the hardness of platinum and palladium . The corrosion resistance of titanium is increased markedly by the addition of a small amount of ruthenium. The metal can be plated by electroplating and by thermal decomposition. A ruthenium– molybdenum alloy

3534-411: Is only 0.72%. A natural nuclear reactor is therefore no longer possible on Earth without heavy water or graphite . The Oklo uranium ore deposits are the only known sites in which natural nuclear reactors existed. Other rich uranium ore bodies would also have had sufficient uranium to support nuclear reactions at that time, but the combination of uranium, water, and physical conditions needed to support

3627-454: Is probably lower as its parent nuclide, xenon-135, is a strong neutron poison and will have absorbed neutrons before decaying to Cs in some cases), 28 kilograms (62 lb) of palladium-107 (since decayed to silver), 86 kilograms (190 lb) of strontium-90 (long since decayed to zirconium), and 185 kilograms (408 lb) of caesium-137 (long since decayed to barium). The natural reactor of Oklo has been used to check if

3720-656: Is reduced by cold dilute potassium hydroxide to form black potassium perruthenate, KRuO 4 , with ruthenium in the +7 oxidation state. Potassium perruthenate can also be produced by oxidising potassium ruthenate, K 2 RuO 4 , with chlorine gas. The perruthenate ion is unstable and is reduced by water to form the orange ruthenate. Potassium ruthenate may be synthesized by reacting ruthenium metal with molten potassium hydroxide and potassium nitrate . Some mixed oxides are also known, such as M Ru O 3 , Na 3 Ru O 4 , Na 2 Ru 2 O 7 , and M 2 Ln Ru O 6 . The highest known ruthenium halide

3813-427: Is the hexafluoride , a dark brown solid that melts at 54 °C. It hydrolyzes violently upon contact with water and easily disproportionates to form a mixture of lower ruthenium fluorides, releasing fluorine gas. Ruthenium pentafluoride is a tetrameric dark green solid that is also readily hydrolyzed, melting at 86.5 °C. The yellow ruthenium tetrafluoride is probably also polymeric and can be formed by reducing

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3906-416: Is the first in a downward trend in the melting and boiling points and atomization enthalpy in the 4d transition metals after the maximum seen at molybdenum , because the 4d subshell is more than half full and the electrons are contributing less to metallic bonding. ( Technetium , the previous element, has an exceptionally low value that is off the trend due to its half-filled [Kr]4d 5s configuration, though it

3999-457: Is the largest use of ruthenium. Ru metal is particularly nonvolatile, which is advantageous in microelectronic devices. Ru and its main oxide RuO 2 have comparable electrical resistivities. Copper can be directly electroplated onto ruthenium, particular applications include barrier layers , transistor gates, and interconnects. Ru films can be deposited by chemical vapor deposition using volatile complexes such as ruthenium tetroxide and

4092-587: The Parker 51 fountain pen was fitted with the "RU" nib, a 14K gold nib tipped with 96.2% ruthenium and 3.8% iridium . Ruthenium is a component of mixed-metal oxide (MMO) anodes used for cathodic protection of underground and submerged structures, and for electrolytic cells for such processes as generating chlorine from salt water. The fluorescence of some ruthenium complexes is quenched by oxygen, finding use in optode sensors for oxygen. Ruthenium red , [(NH 3 ) 5 Ru-O-Ru(NH 3 ) 4 -O-Ru(NH 3 ) 5 ] ,

4185-643: The Tricastin uranium enrichment site at Pierrelatte, France, routine mass spectrometry comparing UF 6 samples from the Oklo mine showed a discrepancy in the amount of the U isotope. Where the usual concentrations of U were 0.72% the Oklo samples showed only 0.60%. This was a significant difference—the samples bore 17% less U than expected. This discrepancy required explanation, as all civilian uranium handling facilities must meticulously account for all fissionable isotopes to ensure that none are diverted into

4278-459: The fissile isotope U made up about 3.1% of the natural uranium, which is comparable to the amount used in some of today's reactors. (The remaining 96.9% was U and roughly 55 ppm U , neither of which is fissile by slow or moderated neutrons.) Because U has a shorter half-life than U , and thus decays more rapidly, the current abundance of U in natural uranium

4371-762: The luminescent tris(bipyridine)ruthenium(II) chloride . Ruthenium forms a wide range compounds with carbon–ruthenium bonds. Grubbs' catalyst is used for alkene metathesis. Ruthenocene is analogous to ferrocene structurally, but exhibits distinctive redox properties. The colorless liquid ruthenium pentacarbonyl converts in the absence of CO pressure to the dark red solid triruthenium dodecacarbonyl . Ruthenium trichloride reacts with carbon monoxide to give many derivatives including RuHCl(CO)(PPh 3 ) 3 and Ru(CO) 2 (PPh 3 ) 3 ( Roper's complex ). Heating solutions of ruthenium trichloride in alcohols with triphenylphosphine gives tris(triphenylphosphine)ruthenium dichloride (RuCl 2 (PPh 3 ) 3 ), which converts to

4464-490: The organoruthenium compound ( cyclohexadiene )Ru(CO) 3 . Many ruthenium-containing compounds exhibit useful catalytic properties. Solutions containing ruthenium trichloride are highly active for olefin metathesis . Such catalysts are used commercially for the production of polynorbornene for example. Well defined ruthenium carbene and alkylidene complexes show similar reactivity but are only used on small-scale. The Grubbs' catalysts for example have been employed in

4557-498: The secular equilibrium of 55 ppm U relative to U . This is due to U being enriched together with U and due to it being both consumed by neutron capture and produced from U by fast neutron induced (n,2n) reactions in nuclear reactors. In Oklo any possible deviation of U concentration present at the time the reactor was active would have long since decayed away. U must have also been present in higher than usual ratios during

4650-562: The US and Japan. For detailed petrographic descriptions of ore minerals see Tables for the Determination of Common Opaque Minerals by Spry and Gedlinske (1987). Below are the major economic ore minerals and their deposits, grouped by primary elements. [REDACTED] Media related to Ores at Wikimedia Commons Ruthenium αa 5.77 αc 8.80 Ruthenium is a chemical element ; it has symbol Ru and atomic number 44. It

4743-752: The United States and the Shanghai Futures Exchange in China. The global Chromium market is currently dominated by the United States and China. Iron ore is traded between customer and producer, though various benchmark prices are set quarterly between the major mining conglomerates and the major consumers, and this sets the stage for smaller participants. Other, lesser, commodities do not have international clearing houses and benchmark prices, with most prices negotiated between suppliers and customers one-on-one. This generally makes determining

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4836-553: The acidity of their immediate surroundings and of water, with numerous, long lasting impacts on ecosystems. When water becomes contaminated it may transport these compounds far from the tailings site, greatly increasing the affected range. Uranium ores and those containing other radioactive elements may pose a significant threat if leaving occurs and isotope concentration increases above background levels. Radiation can have severe, long lasting environmental impacts and cause irreversible damage to living organisms. Metallurgy began with

4929-589: The asteroid Vesta discovered shortly before) from South American platinum ores in 1807. He published an announcement of his discovery in 1808. His work was never confirmed, however, and he later withdrew his claim of discovery. Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827. They examined residues that were left after dissolving crude platinum from the Ural Mountains in aqua regia . Berzelius did not find any unusual metals, but Osann thought he found three new metals, which he called pluranium, ruthenium, and polinium. This discrepancy led to

5022-473: The atomic fine-structure constant α might have changed over the past 2 billion years. That is because α influences the rate of various nuclear reactions. For example, Sm captures a neutron to become Sm , and since the rate of neutron capture depends on the value of α , the ratio of the two samarium isotopes in samples from Oklo can be used to calculate the value of α from 2 billion years ago. Several studies have analysed

5115-411: The chain reaction was unique, as far as is currently known, to the Oklo ore bodies. It is also possible that other natural nuclear fission reactors were once operating but have since been geologically disturbed so much as to be unrecognizable, possibly even "diluting" the uranium so far that the isotope ratio would no longer serve as a "fingerprint". Only a small part of the continental crust and no part of

5208-502: The compounds prepared by Gottfried Osann contained small amounts of ruthenium, which Claus had discovered the same year. Claus isolated ruthenium from the platinum residues of rouble production while he was working in Kazan University , Kazan , the same way its heavier congener osmium had been discovered four decades earlier. Claus showed that ruthenium oxide contained a new metal and obtained 6 grams of ruthenium from

5301-473: The concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral. Minerals of interest are generally oxides , sulfides , silicates , or native metals such as copper or gold . Ore bodies are formed by

5394-643: The construction of unsanctioned nuclear weapons . Further, as fissile material is the reason for mining uranium in the first place, the missing 17% was also of direct economic concern. Thus the French Alternative Energies and Atomic Energy Commission (CEA) began an investigation. A series of measurements of the relative abundances of the two most significant isotopes of uranium mined at Oklo showed anomalous results compared to those obtained for uranium from other mines. Further investigations into this uranium deposit discovered uranium ore with

5487-465: The development of a special alloy with 0.1% ruthenium. Ruthenium is also used in some advanced high-temperature single-crystal superalloys , with applications that include the turbines in jet engines . Several nickel based superalloy compositions are described, such as EPM-102 (with 3% Ru), TMS-162 (with 6% Ru), TMS-138, and TMS-174, the latter two containing 6% rhenium . Fountain pen nibs are frequently tipped with ruthenium alloy. From 1944 onward,

5580-471: The dioxide above 100 °C. Unlike iron but like osmium, ruthenium does not form oxides in its lower +2 and +3 oxidation states. Ruthenium forms di chalcogenides , which are diamagnetic semiconductors crystallizing in the pyrite structure. Ruthenium sulfide (RuS 2 ) occurs naturally as the mineral laurite . Like iron, ruthenium does not readily form oxoanions and prefers to achieve high coordination numbers with hydroxide ions instead. Ruthenium tetroxide

5673-417: The direct working of native metals such as gold, lead and copper. Placer deposits, for example, would have been the first source of native gold. The first exploited ores were copper oxides such as malachite and azurite, over 7000 years ago at Çatalhöyük . These were the easiest to work, with relatively limited mining and basic requirements for smelting. It is believed they were once much more abundant on

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5766-410: The environment, Tc is among the most often proposed non- actinides for commercial scale nuclear transmutation. Tc has a relatively large neutron cross section , and because technetium has no stable isotopes, there would not be a problem of neutron activation of stable isotopes. Significant amounts of Tc are produced in nuclear fission. They are also produced as a byproduct of

5859-424: The first eukaryotes , living under a 2% oxygen atmosphere. However even this meager oxygen was likely essential to the concentration of uranium into fissionable ore bodies, as uranium dissolves in water only in the presence of oxygen. Before the planetary-scale production of oxygen by the early photosynthesizers groundwater-moderated natural nuclear reactors are not thought to have been possible. In May 1972, at

5952-432: The fission chain reaction stopped. The natural nuclear reactor at Oklo formed when a uranium-rich mineral deposit became inundated with groundwater , which could act as a moderator for the neutrons produced by nuclear fission. A chain reaction took place, producing heat that caused the groundwater to boil away; without a moderator that could slow the neutrons, however, the reaction slowed or stopped. The reactor thus had

6045-407: The fission of U . The two isotopes Nd and Nd lead to the formation of Nd and Nd by neutron capture. This excess must be corrected (see above) to obtain agreement between this corrected isotopic composition and that deduced from fission yields. Similar investigations into the isotopic ratios of ruthenium at Oklo found

6138-458: The highest concentration of any single metal available. They are composed of chert beds alternating between high and low iron concentrations. Their deposition occurred early in Earth's history when the atmospheric composition was significantly different from today. Iron rich water is thought to have upwelled where it oxidized to Fe (III) in the presence of early photosynthetic plankton producing oxygen. This iron then precipitated out and deposited on

6231-455: The hydride complex chlorohydridotris(triphenylphosphine)ruthenium(II) (RuHCl(PPh 3 ) 3 ). Though naturally occurring platinum alloys containing all six platinum-group metals were used for a long time by pre-Columbian Americans and known as a material to European chemists from the mid-16th century, not until the mid-18th century was platinum identified as a pure element. That natural platinum contained palladium, rhodium, osmium and iridium

6324-626: The main tin source, began. Some 3000 years ago, the smelting of iron ores began in Mesopotamia . Iron oxide is quite abundant on the surface and forms from a variety of processes. Until the 18th century gold, copper, lead, iron, silver, tin, arsenic and mercury were the only metals mined and used. In recent decades, Rare Earth Elements have been increasingly exploited for various high-tech applications. This has led to an ever-growing search for REE ore and novel ways of extracting said elements. Ores (metals) are traded internationally and comprise

6417-516: The mined platinum group metal (PGM) mixtures varies widely, depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2% (1992). Ruthenium, osmium, and iridium are considered the minor platinum group metals. Ruthenium, like the other platinum group metals, is obtained commercially as

6510-423: The most abundant isotope, Ru, is electron capture while the primary mode after is beta emission . The primary decay product before Ru is technetium and the primary decay product after is rhodium . Ru is a product of fission of a nucleus of uranium or plutonium . High concentrations of detected atmospheric Ru were associated with an alleged undeclared nuclear accident in Russia in 2017. Ruthenium

6603-471: The most common. The most prevalent precursor is ruthenium trichloride , a red solid that is poorly defined chemically but versatile synthetically. Ruthenium can be oxidized to ruthenium(IV) oxide (RuO 2 , oxidation state +4), which can, in turn, be oxidized by sodium metaperiodate to the volatile yellow tetrahedral ruthenium tetroxide , RuO 4 , an aggressive, strong oxidizing agent with structure and properties analogous to osmium tetroxide . RuO 4

6696-452: The most stable are Ru with a half-life of 373.59 days, Ru with a half-life of 39.26 days and Ru with a half-life of 2.9 days. Fifteen other radioisotopes have been characterized with atomic weights ranging from 89.93  Da ( Ru) to 114.928 Da ( Ru). Most of these have half-lives that are less than five minutes; the exceptions are Ru (half-life: 1.643 hours) and Ru (half-life: 4.44 hours). The primary decay mode before

6789-526: The name of a god or goddess) or the code name of the resource company which found it (e.g. MKD-5 was the in-house name for the Mount Keith nickel sulphide deposit ). Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis . The following is a general categorization of the main ore deposit types: Magmatic deposits are ones who originate directly from magma These are ore deposits which form as

6882-403: The new aerobic environment available on Earth at the time, these concentrations probably could not have taken place. It is estimated that nuclear reactions in the uranium in centimeter- to meter-sized veins consumed about five tons of U and elevated temperatures to a few hundred degrees Celsius. Most of the non-volatile fission products and actinides have only moved centimeters in

6975-582: The ocean floor. The banding is thought to be a result of changing plankton population. Sediment Hosted Copper forms from the precipitation of a copper rich oxidized brine into sedimentary rocks. These are a source of copper primarily in the form of copper-sulfide minerals. Placer deposits are the result of weathering, transport, and subsequent concentration of a valuable mineral via water or wind. They are typically sources of gold (Au), platinum group elements (PGE), sulfide minerals , tin (Sn), tungsten (W), and rare-earth elements (REEs). A placer deposit

7068-403: The oceanic crust reaches the age of the deposits at Oklo or an age during which isotope ratios of natural uranium would have allowed a self sustaining chain reaction with water as a moderator. Another factor which probably contributed to the start of the Oklo natural nuclear reactor at 2 billion years, rather than earlier, was the increasing oxygen content in the Earth's atmosphere . Uranium

7161-403: The ore from the gangue, and concentration to separate the desired mineral(s) from it. Once processed, the gangue is known as tailings , which are useless but potentially harmful materials produced in great quantity, especially from lower grade deposits. An ore deposit is an economically significant accumulation of minerals within a host rock. This is distinct from a mineral resource in that it

7254-448: The outermost shell, in ruthenium the outermost shell has only one electron (the final electron is in a lower shell). This anomaly is also observed in the neighboring metals niobium (41), molybdenum (42), and rhodium (45). Ruthenium has four crystal modifications and does not tarnish at ambient conditions; it oxidizes upon heating to 800 °C (1,070 K). Ruthenium dissolves in fused alkalis to give ruthenates ( RuO 4 ). It

7347-400: The part of crude platinum that is insoluble in aqua regia . Choosing the name for the new element, Claus stated: "I named the new body, in honour of my Motherland, ruthenium. I had every right to call it by this name because Mr. Osann relinquished his ruthenium and the word does not yet exist in chemistry." The name itself derives from the Latin word Ruthenia . In doing so, Claus started

7440-432: The pentafluoride with iodine . Among the binary compounds of ruthenium, these high oxidation states are known only in the oxides and fluorides. Ruthenium trichloride is a well-known compound, existing in a black α-form and a dark brown β-form: the trihydrate is red. Of the known trihalides, trifluoride is dark brown and decomposes above 650 °C, tribromide is dark-brown and decomposes above 400 °C, and triiodide

7533-483: The preparation of drugs and advanced materials. Some ruthenium complexes are highly active catalysts for transfer hydrogenations (sometimes referred to as "borrowing hydrogen" reactions). Chiral ruthenium complexes, introduced by Ryoji Noyori , are employed for the enantioselective hydrogenation of ketones , aldehydes , and imines . A typical catalyst is (cymene)Ru(S,S-Ts DPEN ): A Nobel Prize in Chemistry

7626-431: The price of ores of this nature opaque and difficult. Such metals include lithium , niobium - tantalum , bismuth , antimony and rare earths . Most of these commodities are also dominated by one or two major suppliers with >60% of the world's reserves. China is currently leading in world production of Rare Earth Elements. The World Bank reports that China was the top importer of ores and metals in 2005 followed by

7719-400: The product of neutron capture in xenon-135 decays extremely slowly via double beta decay and thus scientists were able to determine the neutronics of this reactor by calculations based on those isotope ratios almost two billion years after it stopped fissioning uranium. A key factor that made the reaction possible was that, at the time the reactor went critical 1.7 billion years ago,

7812-463: The relative concentrations of radioactive isotopes left behind at Oklo, and most have concluded that nuclear reactions then were much the same as they are today, which implies that α was the same too. Ore deposit Ore is natural rock or sediment that contains one or more valuable minerals , typically including metals , concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to

7905-471: The surface than today. After this, copper sulphides would have been turned to as oxide resources depleted and the Bronze Age progressed. Lead production from galena smelting may have been occurring at this time as well. The smelting of arsenic-copper sulphides would have produced the first bronze alloys. The majority of bronze creation however required tin, and thus the exploitation of cassiterite,

7998-419: The time the reactor was operating, but due to its half life of 2.348 × 10 years being almost two orders of magnitude shorter than the time elapsed since the reactor operated, it has decayed to roughly 1.4 × 10 its original value and thus basically nothing and below any abilities of current equipment to detect. This loss in U is exactly what happens in a nuclear reactor. A possible explanation

8091-490: The use of Tc in nuclear medicine , because this isomer decays to Tc . Exposing the Tc target to strong enough neutron radiation will eventually yield appreciable quantities of ruthenium, which can be chemically separated while consuming Tc . The oxidation states of ruthenium range from 0 to +8, and −2. The properties of ruthenium and osmium compounds are often similar. The +2, +3, and +4 states are

8184-419: The veins during the last 2 billion years. Studies have suggested this as a useful natural analogue for nuclear waste disposal. The overall mass defect from the fission of five tons of U is about 4.6 kilograms (10 lb). Over its lifetime the reactor produced roughly 100 megatonnes of TNT (420 PJ) in thermal energy, including neutrinos . If one ignores fission of plutonium (which makes up roughly

8277-490: The volatile oxides, RuO 4 is separated from OsO 4 by precipitation of (NH 4 ) 3 RuCl 6 with ammonium chloride or by distillation or extraction with organic solvents of the volatile osmium tetroxide. Hydrogen is used to reduce ammonium ruthenium chloride, yielding a powder. The product is reduced using hydrogen, yielding the metal as a powder or sponge metal that can be treated with powder metallurgy techniques or argon - arc welding . Ruthenium

8370-555: Was active in Oklo , Gabon, some two billion years ago. Indeed, the isotope ratio of ruthenium found there was one of several ways used to confirm that a nuclear fission chain reaction had indeed occurred at that site in the geological past. Uranium is no longer mined at Oklo, and there have never been serious attempts to recover any of the platinum group metals present there. Roughly 30 tonnes of ruthenium are mined each year, and world reserves are estimated at 5,000 tonnes. The composition of

8463-513: Was awarded in 2001 to Ryōji Noyori for contributions to the field of asymmetric hydrogenation . Ruthenium-promoted cobalt catalysts are used in Fischer–Tropsch synthesis . Ruthenium-based compounds are components of dye-sensitized solar cells , which are proposed as low-cost solar cell system. Little is known about the health effects of ruthenium and it is relatively rare for people to encounter ruthenium compounds. Metallic ruthenium

8556-670: Was discovered in the first decade of the 19th century. Platinum in alluvial sands of Russian rivers gave access to raw material for use in plates and medals and for the minting of ruble coins , starting in 1828. Residues from platinum production for coinage were available in the Russian Empire, and therefore most of the research on them was done in Eastern Europe. It is possible that the Polish chemist Jędrzej Śniadecki isolated element 44 (which he called "vestium" after

8649-456: Was that the uranium ore had operated as a natural fission reactor in the distant geological past. Other observations led to the same conclusion, and on 25 September 1972 the CEA announced their finding that self-sustaining nuclear chain reactions had occurred on Earth about 2 billion years ago. Later, other natural nuclear fission reactors were discovered in the region. The neodymium found at Oklo has

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