| 0 | Molybdenum hexacarbonyl
|-
| +1||Cyclopentadienylmolybdenum tricarbonyl
|-
| +2||Molybdenum(II) chloride
|-
| +3||Molybdenum(III) bromide
|-
| +4||Molybdenum disulfide
|-
| +5||Molybdenum(V) chloride
|-
| +6||Molybdenum(VI) fluoride
|}
File:Phosphotungstate-3D-polyhedra.png of the phosphomolybdate anion (P[Mo12O40]3−), an example of a polyoxometalate]]
From the perspective of commerce, the most important compounds are molybdenum disulfide ({{chem|MoS|2}}) and molybdenum trioxide ({{chem|MoO|3}}). The black disulfide is the main mineral. It is roasted in air to give the trioxide:
:2 {{chem|MoS|2}} + 7 {{chem|O|2}} → 2 {{chem|MoO|3}} + 4 {{chem|SO|2}}
The trioxide, which is volatile at high temperatures, is the precursor to virtually all other Mo compounds as well as alloys. Molybdenum has several oxidation states, the most stable being +4 and +6 (bolded in the table at left).
Molybdenum(VI) oxide is soluble in strong alkaline water, forming molybdates (MoO42−). Molybdates are weaker oxidants than chromates. They tend to form structurally complex oxyanions by condensation at lower pH values, such as [Mo7O24]6− and [Mo8O26]4−. Polymolybdates can incorporate other ions, forming polyoxometalates.[{{cite journal|journal = Angewandte Chemie International Edition|volume = 30|pages=34–48|date = 1997|title = Polyoxometalate Chemistry: An Old Field with New Dimensions in Several Disciplines|first1 = Michael T.|last1 = Pope|last2= Müller |first2 = Achim|doi = 10.1002/anie.199100341}}] The dark-blue phosphorus-containing heteropolymolybdate P[Mo12O40]3− is used for the spectroscopic detection of phosphorus.[{{cite book|isbn = 978-0-8247-8433-1|pages = 280–288|editor = Nollet, Leo M. L.|date = 2000|publisher = Marcel Dekker|location = New York, NY|title = Handbook of water analysis|url=https://books.google.com/books?id=YZpW4Y4Q_PIC&pg=PA280}}]
The broad range of oxidation states of molybdenum is reflected in various molybdenum chlorides:
- Molybdenum(II) chloride MoCl2, which exists as the hexamer Mo6Cl12 and the related dianion [Mo6Cl14]2-.
- Molybdenum(III) chloride MoCl3, a dark red solid, which converts to the anion trianionic complex [MoCl6]3-.
- Molybdenum(IV) chloride MoCl4, a black solid, which adopts a polymeric structure.
- Molybdenum(V) chloride MoCl5 dark green solid, which adopts a dimeric structure.
- Molybdenum(VI) chloride MoCl6 is a black solid, which is monomeric and slowly decomposes to MoCl5 and Cl2 at room temperature.
[{{Cite journal|last1=Tamadon|first1=Farhad|last2=Seppelt|first2=Konrad|date=2013-01-07|title=The Elusive Halides VCl 5, MoCl 6, and ReCl 6|journal=Angewandte Chemie International Edition|language=en|volume=52|issue=2|pages=767–769|doi=10.1002/anie.201207552|pmid=23172658}}]
The accessibility of these oxidation states depends quite strongly on the halide counterion: although molybdenum(VI) fluoride is stable, molybdenum does not form a stable hexachloride, pentabromide, or tetraiodide.[{{Kirk-Othmer|doi=10.1002/0471238961.1315122519200905.a01.pub3|title=Molybdenum Compounds|first=Edward I.|last=Stiefel}}]
Like chromium and some other transition metals, molybdenum forms quadruple bonds, such as in Mo2(CH3COO)4 and [Mo2Cl8]4−.[{{Cite book|title=Inorganic Syntheses: Volume 36 |last1=Walton |first1=Richard A. |last2=Fanwick |first2=Phillip E. |last3=Girolami |first3=Gregory S. |last4=Murillo |first4=Carlos A. |last5=Johnstone |first5=Erik V. |date=2014 |publisher=John Wiley & Sons |isbn=978-1118744994 |editor-last=Girolami |editor-first=Gregory S. |pages=78–81 |language=en |doi=10.1002/9781118744994.ch16 |editor-last2=Sattelberger |editor-first2=Alfred P.}}] The Lewis acid properties of the butyrate and perfluorobutyrate dimers, Mo2(O2CR)4 and Rh2(O2CR) 4, have been reported.[{{Cite journal |last1=Drago |first1=Russell S. |last2=Long |first2=John R. |last3=Cosmano |first3=Richard |date=1982-06-01 |title=Comparison of the coordination chemistry and inductive transfer through the metal-metal bond in adducts of dirhodium and dimolybdenum carboxylates |journal=Inorganic Chemistry |language=en |volume=21 |issue=6 |pages=2196–2202 |doi=10.1021/ic00136a013 |issn=0020-1669}}]
The oxidation state 0 and lower are possible with carbon monoxide as ligand, such as in molybdenum hexacarbonyl, Mo(CO)6. HistoryMolybdenite—the principal ore from which molybdenum is now extracted—was previously known as molybdena. Molybdena was confused with and often utilized as though it were graphite. Like graphite, molybdenite can be used to blacken a surface or as a solid lubricant.[{{cite book |last1=Lansdown |first1=A. R. |title=Molybdenum disulphide lubrication |volume=35 |series=Tribology and Interface Engineering |publisher=Elsevier |date=1999 |isbn=978-0-444-50032-8}}] Even when molybdena was distinguishable from graphite, it was still confused with the common lead ore PbS (now called galena); the name comes from Ancient Greek {{lang|grc|Μόλυβδος}} {{lang|grc-Latn|molybdos}}, meaning lead.[{{cite web| author=Melchert, Craig| title=Greek mólybdos as a Loanword from Lydian| publisher=University of North Carolina at Chapel Hill| url=http://www.linguistics.ucla.edu/people/melchert/webpage/molybdos.pdf| access-date=2011-04-23| archive-url=https://web.archive.org/web/20131231000505/http://www.linguistics.ucla.edu/people/Melchert/webpage/molybdos.pdf| archive-date=2013-12-31| url-status=live}}]
Although (reportedly) molybdenum was deliberately alloyed with steel in one 14th-century Japanese sword (mfd. {{Circa|1330}}), that art was never employed widely and was later lost.[{{cite web |title=Molybdenum History |publisher=International Molybdenum Association |archive-url=https://web.archive.org/web/20130722102351/http://www.imoa.info/molybdenum/molydbenum_history.php |archive-date=2013-07-22 |url=http://www.imoa.info/molybdenum/molydbenum_history.php}}][{{cite book |title=Accidental use of molybdenum in old sword led to new alloy |url=https://books.google.com/books?id=yUpYAAAAMAAJ&q=Japanese+sword+molybdenum |publisher=American Iron and Steel Institute |date=1948}}] In the West in 1754, Bengt Andersson Qvist examined a sample of molybdenite and determined that it did not contain lead and thus was not galena.[{{cite web |last=Van der Krogt |first=Peter |title=Molybdenum |work=Elementymology & Elements Multidict |date=2006-01-10 |url=http://elements.vanderkrogt.net/element.php?sym=Mo |access-date=2007-05-20 |archive-url=https://web.archive.org/web/20100123002743/http://elements.vanderkrogt.net/element.php?sym=Mo |archive-date=2010-01-23 |url-status=dead}}]
By 1778 Swedish chemist Carl Wilhelm Scheele stated firmly that molybdena was (indeed) neither galena nor graphite.[{{cite web|last = Gagnon|first = Steve|title = Molybdenum|publisher = Jefferson Science Associates, LLC|url = http://education.jlab.org/itselemental/ele042.html|access-date = 2007-05-06|archive-url = https://web.archive.org/web/20070426150528/http://education.jlab.org/itselemental/ele042.html|archive-date = 2007-04-26|url-status = dead}}][{{cite journal|author = Scheele, C. W. K.|title = Versuche mit Wasserbley; Molybdaena|journal = Svenska Vetensk. Academ. Handlingar|page=238|date = 1779|volume = 40|url = http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=PPN324352840_0040}}] Instead, Scheele correctly proposed that molybdena was an ore of a distinct new element, named molybdenum for the mineral in which it resided, and from which it might be isolated. Peter Jacob Hjelm successfully isolated molybdenum using carbon and linseed oil in 1781.[{{cite journal|author = Hjelm, P. J.|title = Versuche mit Molybdäna, und Reduction der selben Erde|journal = Svenska Vetensk. Academ. Handlingar|page = 268|date = 1788|volume = 49|url = http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=PPN324352840_0009_02_NS}}]
For the next century, molybdenum had no industrial use. It was relatively scarce, the pure metal was difficult to extract, and the necessary techniques of metallurgy were immature.[{{cite book | last1 = Hoyt | first1 = Samuel Leslie | title = Metallography | volume = 2 | publisher = McGraw-Hill | date = 1921 }}][{{cite book | last1 = Krupp | first1 = Alfred | last2 = Wildberger | first2 = Andreas | title = The metallic alloys: A practical guide for the manufacture of all kinds of alloys, amalgams, and solders, used by metal-workers ... with an appendix on the coloring of alloys | publisher = H.C. Baird & Co. | date = 1888 | page = 60 }}][{{cite book | last1 = Gupta | first1 = C. K. | title = Extractive Metallurgy of Molybdenum | publisher = CRC Press | date = 1992 | isbn = 978-0-8493-4758-0}}] Early molybdenum steel alloys showed great promise of increased hardness, but efforts to manufacture the alloys on a large scale were hampered with inconsistent results, a tendency toward brittleness, and recrystallization. In 1906, William D. Coolidge filed a patent for rendering molybdenum ductile, leading to applications as a heating element for high-temperature furnaces and as a support for tungsten-filament light bulbs; oxide formation and degradation require that molybdenum be physically sealed or held in an inert gas.[{{cite book | url = https://books.google.com/books?id=ZVkZNyVI4toC&pg=PA117 | page = 117 | title = The Making of American Industrial Research: Science and Business at Ge and Bell, 1876–1926 | isbn = 978-0521522373 | last1 = Reich | first1 = Leonard S. | date = 2002-08-22 | publisher = Cambridge University Press | access-date = 2016-04-07 | archive-url = https://web.archive.org/web/20140709171645/http://books.google.com/books?id=ZVkZNyVI4toC&pg=PA117 | archive-date = 2014-07-09 | url-status = live }}] In 1913, Frank E. Elmore developed a froth flotation process to recover molybdenite from ores; flotation remains the primary isolation process.[{{cite book | url = https://books.google.com/books?id=HT4aAQAAIAAJ&q=Elmore+flotation+molybdenum+1913| page = 3 | title = Molybdenum deposits of Canada | last1 = Vokes | first1 = Frank Marcus | date = 1963}}]
During World War I, demand for molybdenum spiked; it was used both in armor plating and as a substitute for tungsten in high-speed steels. Some British tanks were protected by 75 mm (3 in) manganese steel plating, but this proved to be ineffective. The manganese steel plates were replaced with much lighter {{Convert|25|mm|inch|1|abbr=on}} molybdenum steel plates allowing for higher speed, greater maneuverability, and better protection.[[http://www.lenntech.com/periodic/elements/mo.htm Chemical properties of molibdenum – Health effects of molybdenum – Environmental effects of molybdenum] {{Webarchive|url=https://web.archive.org/web/20160120203530/http://www.lenntech.com/periodic/elements/mo.htm |date=2016-01-20}}. lenntech.com] because traditional steel melts at the temperatures produced by the propellant of the one ton shell.[{{Cite book |last=Kean |first=Sam |title=The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements |date=2011-06-06 |publisher=Back Bay Books |isbn=978-0-316-05163-7 |edition=Illustrated |pages=88–89 |language=English}}] After the war, demand plummeted until metallurgical advances allowed extensive development of peacetime applications. In World War II, molybdenum again saw strategic importance as a substitute for tungsten in steel alloys.[{{cite journal | first = Ray | last = Millholland | title = Battle of the Billions: American industry mobilizes machines, materials, and men for a job as big as digging 40 Panama Canals in one year | date = August 1941 | journal = Popular Science | page = 61 | url = https://books.google.com/books?id=xScDAAAAMBAJ&pg=PA56 | access-date = 2016-04-07 | archive-url = https://web.archive.org/web/20140709161654/http://books.google.com/books?id=xScDAAAAMBAJ&pg=PA56 | archive-date = 2014-07-09 | url-status = live }}] Occurrence and productionFile:Molly Hill molybdenite.JPG on quartz]]
Molybdenum is the 54th most abundant element in the Earth's crust with an average of 1.5 parts per million and the 25th most abundant element in the oceans, with an average of 10 parts per billion; it is the 42nd most abundant element in the Universe.[{{cite book|contribution = Molybdenum|date = 2005|title = Van Nostrand's Encyclopedia of Chemistry|pages = 1038–1040|place= New York|publisher = Wiley-Interscience|isbn=978-0-471-61525-5|editor= Considine, Glenn D.}}] The Soviet Luna 24 mission discovered a molybdenum-bearing grain (1 × 0.6 μm) in a pyroxene fragment taken from Mare Crisium on the Moon.[{{cite journal|url=http://www.minsocam.org/msa/AmMin/TOC/Abstracts/2002_Abstracts/Jan02_Abstracts/Jambor_p181_02.pdf|title=New mineral names|journal=American Mineralogist|volume=87|page=181|date=2002|author=Jambor, J.L.|display-authors=etal|access-date=2007-04-09|archive-url=https://web.archive.org/web/20070710054017/http://www.minsocam.org/msa/AmMin/TOC/Abstracts/2002_Abstracts/Jan02_Abstracts/Jambor_p181_02.pdf|archive-date=2007-07-10|url-status=live}}] The comparative rarity of molybdenum in the Earth's crust is offset by its concentration in a number of water-insoluble ores, often combined with sulfur in the same way as copper, with which it is often found. Though molybdenum is found in such minerals as wulfenite (PbMoO4) and powellite (CaMoO4), the main commercial source is molybdenite (MoS2). Molybdenum is mined as a principal ore and is also recovered as a byproduct of copper and tungsten mining.
The world's production of molybdenum was 250,000 tonnes in 2011, the largest producers being China (94,000 t), the United States (64,000 t), Chile (38,000 t), Peru (18,000 t) and Mexico (12,000 t). The total reserves are estimated at 10 million tonnes, and are mostly concentrated in China (4.3 Mt), the US (2.7 Mt) and Chile (1.2 Mt). By continent, 93% of world molybdenum production is about evenly shared between North America, South America (mainly in Chile), and China. Europe and the rest of Asia (mostly Armenia, Russia, Iran and Mongolia) produce the remainder.
File:Molybdenum world production.svg
In molybdenite processing, the ore is first roasted in air at a temperature of {{convert|700|°C|°F}}. The process gives gaseous sulfur dioxide and the molybdenum(VI) oxide:
:2MoS2 + 7O2 -> 2MoO3 + 4SO2
The resulting oxide is then usually extracted with aqueous ammonia to give ammonium molybdate:
:MoO3 + 2NH3 + H2O -> (NH4)2(MoO4)
Copper, an impurity in molybdenite, is separated at this stage by treatment with hydrogen sulfide.[{{cite book|doi=10.1002/14356007.a16_655|chapter=Molybdenum and Molybdenum Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |last1=Sebenik |first1=Roger F. |last2=Burkin |first2=A. Richard |last3=Dorfler |first3=Robert R. |last4=Laferty |first4=John M. |last5=Leichtfried |first5=Gerhard |last6=Meyer-Grünow |first6=Hartmut |last7=Mitchell |first7=Philip C. H. |last8=Vukasovich |first8=Mark S. |last9=Church |first9=Douglas A. |last10=Van Riper |first10=Gary G. |last11=Gilliland |first11=James C. |last12=Thielke |first12=Stanley A. |isbn=3527306730 |s2cid=98762721 }}]
: (NH4)2Mo2O7 -> 2MoO3 + 2NH3 + H2O
Crude trioxide can be further purified by sublimation at {{convert|1100|°C|°F}}.
Metallic molybdenum is produced by reduction of the oxide with hydrogen:
:MoO3 + 3H2 -> Mo + 3H2O
The molybdenum for steel production is reduced by the aluminothermic reaction with addition of iron to produce ferromolybdenum. A common form of ferromolybdenum contains 60% molybdenum.[{{cite book|publisher = Walter de Gruyter|date = 1985|edition = 91–100|pages = 1096–1104|isbn = 978-3-11-007511-3|title = Lehrbuch der Anorganischen Chemie|author=Holleman, Arnold F. |author2=Wiberg, Egon |author3=Wiberg, Nils}}][{{cite book|last = Gupta|first = C. K.|title = Extractive Metallurgy of Molybdenum|publisher = CRC Press|date= 1992|pages = 1–2|isbn = 978-0-8493-4758-0}}]
Molybdenum had a value of approximately $30,000 per tonne as of August 2009. It maintained a price at or near $10,000 per tonne from 1997 through 2003, and reached a peak of $103,000 per tonne in June 2005.[{{cite web|title = Dynamic Prices and Charts for Molybdenum|publisher = InfoMine Inc.|date = 2007|url = http://www.infomine.com/investment/charts.aspx?c=molybdenum&u=mt&submit1=Display+Chart&x=usd&r=15y#chart|access-date = 2007-05-07|archive-url = https://web.archive.org/web/20091008202153/http://www.infomine.com/investment/charts.aspx?c=molybdenum&u=mt&submit1=Display+Chart&x=usd&r=15y#chart|archive-date = 2009-10-08|url-status = live}}] In 2008, the London Metal Exchange announced that molybdenum would be traded as a commodity.[{{cite web |title=LME to launch minor metals contracts in H2 2009 |url=http://www.lme.com/6241.asp |date=2008-09-04 |publisher=London Metal Exchange |access-date=2009-07-28 |archive-url=https://web.archive.org/web/20120722014344/http://www.lme.com/6241.asp |archive-date=2012-07-22 }}] =Mining=The Knaben mine in southern Norway, opened in 1885, was the first dedicated molybdenum mine. Closed in 1973 but reopened in 2007,[{{cite journal |doi = 10.1016/S0375-6742(96)00069-6 |title = Dispersion of tailings in the Knabena—Kvina drainage basin, Norway, 1: Evaluation of overbank sediments as sampling medium for regional geochemical mapping |date = 1997 |last1 = Langedal |first1 = M. |journal = Journal of Geochemical Exploration |volume = 58 |pages= 157–172 |issue = 2–3|bibcode = 1997JCExp..58..157L }}] it now produces {{Convert|100000|kg|ton|0}} of molybdenum disulfide per year. Large mines in Colorado (such as the Henderson mine and the Climax mine)[{{cite journal|first= Paul B. |last = Coffman |title = The Rise of a New Metal: The Growth and Success of the Climax Molybdenum Company |journal = The Journal of Business of the University of Chicago |page= 30|date = 1937 |volume = 10 |doi = 10.1086/232443}}] and in British Columbia yield molybdenite as their primary product, while many porphyry copper deposits such as the Bingham Canyon Mine in Utah and the Chuquicamata mine in northern Chile produce molybdenum as a byproduct of copper-mining. =Alloys=File:Plate of Molybdenum Copper .jpg
About 86% of molybdenum produced is used in metallurgy, with the rest used in chemical applications. The estimated global use is structural steel 35%, stainless steel 25%, chemicals 14%, tool & high-speed steels 9%, cast iron 6%, molybdenum elemental metal 6%, and superalloys 5%.[{{cite web |url=http://www.lme.com/minormetals/6782.asp |archive-url=https://web.archive.org/web/20120310004452/http://www.lme.com/minormetals/6782.asp |archive-date=2012-03-10 |title=Molybdenum |work=Industry usage |publisher=London Metal Exchange}}]
Molybdenum can withstand extreme temperatures without significantly expanding or softening, making it useful in environments of intense heat, including military armor, aircraft parts, electrical contacts, industrial motors, and supports for filaments in light bulbs.
Most high-strength steel alloys (for example, 41xx steels) contain 0.25% to 8% molybdenum.
Molybdenum is also used in steel alloys for its high corrosion resistance and weldability.[{{cite web|title = Molybdenum Statistics and Information|publisher = U.S. Geological Survey|date = 2007-05-10|url = http://minerals.usgs.gov/minerals/pubs/commodity/molybdenum/|access-date = 2007-05-10|archive-url = https://web.archive.org/web/20070519151353/http://minerals.usgs.gov/minerals/pubs/commodity/molybdenum/|archive-date = 2007-05-19|url-status = live}}] Molybdenum contributes corrosion resistance to type-300 stainless steels (specifically type-316) and especially so in the so-called superaustenitic stainless steels (such as alloy AL-6XN, 254SMO and 1925hMo). Molybdenum increases lattice strain, thus increasing the energy required to dissolve iron atoms from the surface.{{contradictory inline|date=September 2018}} Molybdenum is also used to enhance the corrosion resistance of ferritic (for example grade 444)[(2023) Stainless Steel Grades and Properties. International Molybdenum Association. https://www.imoa.info/molybdenum-uses/molybdenum-grade-stainless-steels/steel-grades.php?m=1683978651&] and martensitic (for example 1.4122 and 1.4418) stainless steels.{{citation needed|date=December 2014}}
Because of its lower density and more stable price, molybdenum is sometimes used in place of tungsten.[{{cite web|title=Molybdenum|publisher=AZoM.com Pty. Limited|date=2007|url=http://www.azom.com/article.aspx?ArticleID=616|access-date=2007-05-06|archive-url=https://web.archive.org/web/20110614171110/http://www.azom.com/article.aspx?ArticleID=616|archive-date=2011-06-14|url-status=dead}}]
TZM (Mo (~99%), Ti (~0.5%), Zr (~0.08%) and some C) is a corrosion-resisting molybdenum superalloy that resists molten fluoride salts at temperatures above {{convert|1300|°C|°F|abbr=on}}. It has about twice the strength of pure Mo, and is more ductile and more weldable, yet in tests it resisted corrosion of a standard eutectic salt (FLiBe) and salt vapors used in molten salt reactors for 1100 hours with so little corrosion that it was difficult to measure.[{{cite book|last=Smallwood|first=Robert E.|title=ASTM special technical publication 849: Refractory metals and their industrial applications: a symposium|chapter-url=https://books.google.com/books?id=agaacIr25KcC&pg=PA9|date=1984|publisher=ASTM International|isbn=978-0803102033|page=9|chapter=TZM Moly Alloy}}][{{cite web|url = http://www.energyfromthorium.com/forum/download/file.php?id=805|title = Compatibility of Molybdenum-Base Alloy TZM, with LiF-BeF2-ThF4-UF4|publisher = Oak Ridge National Laboratory Report|access-date = 2010-09-02|date = December 1969|archive-url = https://web.archive.org/web/20110710192254/http://www.energyfromthorium.com/forum/download/file.php?id=805|archive-date = 2011-07-10|url-status = dead}}] Due to its excellent mechanical properties under high temperature and high pressure, TZM alloys are extensively applied in the military industry.[{{cite web |url=https://apps.dtic.mil/sti/pdfs/AD0618935.pdf |title=A protective coating system for a TZM alloy re-entry vehicle |website=US Army |last=Levy |first=M. |date=1965 |access-date=June 3, 2024}}] It is used as the valve body of torpedo engines, rocket nozzles and gas pipelines, where it can withstand extreme thermal and mechanical stresses.[{{cite journal |last1=Yang |first1=Zhi |last2=Hu |first2=Ke |date=2018 |title=Diffusion bonding between TZM alloy and WRe alloy by spark plasma sintering |journal=Journal of Alloys and Compounds |volume=764 |pages=582–590 |doi=10.1016/j.jallcom.2018.06.111}}][{{cite patent |country=CN |status=patent |number=109590476B}}] It is also used as radiation shields in nuclear applications.[{{cite web |url=https://www.samaterials.com/content/preparation-application-of-tzm-alloy.html |title=Preparation & Application of TZM Alloy |last=Trento |first=Chin |website=Stanford Advanced Materials |date=Dec 27, 2023 |access-date=June 3, 2024}}]
Other molybdenum-based alloys that do not contain iron have only limited applications. For example, because of its resistance to molten zinc, both pure molybdenum and molybdenum-tungsten alloys (70%/30%) are used for piping, stirrers and pump impellers that come into contact with molten zinc.[{{cite book|title =Tool and manufacturing engineers handbook|first = W. H.|last = Cubberly|author2=Bakerjian, Ramon|publisher = Society of Manufacturing Engineers|isbn = 978-0-87263-351-3|url = https://books.google.com/books?id=NRXnXmFRjWYC&pg=PT421|page = 421|date =1989}}] =Pure element applications=
- Molybdenum powder is used as a fertilizer for some plants, such as cauliflower.
- Elemental molybdenum is used in NO, NO2, NOx analyzers in power plants for pollution controls. At {{convert|350|°C|°F|abbr=on}}, the element acts as a catalyst for NO2/NOx to form NO molecules for detection by infrared light.
[{{cite journal|doi = 10.1023/A:1010730821844|date = 2001|last1= Lal|first1 = S.|last2 = Patil|first2 = R. S.|s2cid = 20441999|journal = Environmental Monitoring and Assessment|volume = 68|pages= 37–50|pmid = 11336410|title = Monitoring of atmospheric behaviour of NOx from vehicular traffic|issue = 1| bibcode=2001EMnAs..68...37L }}]
- Molybdenum anodes replace tungsten in certain low voltage X-ray sources for specialized uses such as mammography.
[{{cite book|title=Physics of Medical X-Ray Imaging|chapter-url=http://ric.uthscsa.edu/personalpages/lancaster/DI-II_Chapters/DI_chap4.pdf|chapter=Ch. 4: Physical determinants of contrast|author=Lancaster, Jack L.|publisher=University of Texas Health Science Center|url-status=dead|archive-url=https://web.archive.org/web/20151010172937/http://ric.uthscsa.edu/personalpages/lancaster/DI-II_Chapters/DI_chap4.pdf|archive-date=2015-10-10}}]
- The radioactive isotope molybdenum-99 is used to generate technetium-99m, used for medical imaging
[Gray, Theodore (2009). The Elements. Black Dog & Leventhal. pp. 105–107. {{ISBN|1-57912-814-9}}.] The isotope is handled and stored as the molybdate.[{{cite journal|doi = 10.1146/annurev.me.20.020169.001023|pmid = 4894500|date = 1969|last1 = Gottschalk|first1 = A.|title = Technetium-99m in clinical nuclear medicine|volume = 20|pages = 131–40|journal = Annual Review of Medicine|issue=1}}]
=Compound applications=
- Molybdenum disulfide (MoS2) is used as a solid lubricant and a high-pressure high-temperature (HPHT) anti-wear agent. It forms strong films on metallic surfaces and is a common additive to HPHT greases — in the event of a catastrophic grease failure, a thin layer of molybdenum prevents contact of the lubricated parts.
[{{cite journal|doi =10.1016/0043-1648(67)90187-1|title =Molybdenum disulfide as a lubricant: A review of the fundamental knowledge |date =1967|last1 =Winer|first1 =W.|journal =Wear|volume =10|pages=422–452|issue =6|hdl =2027.42/33266 |url =https://deepblue.lib.umich.edu/bitstream/2027.42/33266/1/0000658.pdf|hdl-access =free}}]
- When combined with small amounts of cobalt, MoS2 is also used as a catalyst in the hydrodesulfurization (HDS) of petroleum. In the presence of hydrogen, this catalyst facilitates the removal of nitrogen and especially sulfur from the feedstock, which otherwise would poison downstream catalysts. HDS is one of the largest scale applications of catalysis in industry.
[{{cite book| author =Topsøe, H. |author2=Clausen, B. S. |author3=Massoth, F. E. | title =Hydrotreating Catalysis, Science and Technology| publisher = Springer-Verlag| location= Berlin| date = 1996}}]
- Molybdenum oxides are important catalysts for selective oxidation of organic compounds. The production of the commodity chemicals acrylonitrile and formaldehyde relies on MoOx-based catalysts.
- Molybdenum disilicide (MoSi2) is an electrically conducting ceramic with primary use in heating elements operating at temperatures above 1500 °C in air.
[{{cite book|url=https://books.google.com/books?id=FbMfaqSgOxsC&pg=PA141|page=141|title=Electroceramics: materials, properties, applications|author=Moulson, A. J. |author2=Herbert, J. M.|publisher=John Wiley and Sons|date=2003|isbn=978-0-471-49748-6}}]
- Molybdenum trioxide (MoO3) is used as an adhesive between enamels and metals.
- Lead molybdate (wulfenite) co-precipitated with lead chromate and lead sulfate is a bright-orange pigment used with ceramics and plastics.
[[http://www.imoa.info/ International Molybdenum Association] {{Webarchive|url=https://web.archive.org/web/20080309010036/http://www.imoa.info/ |date=2008-03-09 }}. imoa.info.]
- The molybdenum-based mixed oxides are versatile catalysts in the chemical industry. Some examples are the catalysts for the oxidation of carbon monoxide, propylene to acrolein and acrylic acid, the ammoxidation of propylene to acrylonitrile.
[{{cite book|editor=Fierro, J. G. L. |title=Metal Oxides, Chemistry and Applications|date=2006|publisher=CRC Press|pages=414–455}}][{{cite book|author1=Centi, G. |author2=Cavani, F. |author3=Trifiro, F. |title=Selective Oxidation by Heterogeneous Catalysis|date=2001|publisher=Kluwer Academic/Plenum Publishers|pages=363–384}}]
- Molybdenum carbides, nitride and phosphides can be used for hydrotreatment of rapeseed oil.
[{{cite journal |last1=Horáček |first1=Jan |last2=Akhmetzyanova |first2=Uliana |last3=Skuhrovcová |first3=Lenka |last4=Tišler |first4=Zdeněk |last5=de Paz Carmona |first5=Héctor |title=Alumina-supported MoNx, MoCx and MoPx catalysts for the hydrotreatment of rapeseed oil |journal=Applied Catalysis B: Environmental |date=1 April 2020 |volume=263 |pages=118328 |doi=10.1016/j.apcatb.2019.118328 |s2cid=208758175 |language=en |issn=0926-3373|doi-access=free |bibcode=2020AppCB.26318328H }}]
- Ammonium heptamolybdate is used in biological staining.
[{{cite journal |last1=De Carlo |first1=Sacha |last2=Harris |first2=J. Robin |title=Negative staining and cryo-negative staining of macromolecules and viruses for TEM |journal=Micron |volume=42 |date=2011 |issue=2 |pmid=20634082 |pmc=2978762 |doi=10.1016/j.micron.2010.06.003 |pages=117–131}}]
- Molybdenum coated soda lime glass is used in CIGS (copper indium gallium selenide) solar cells, called CIGS solar cells.
- Phosphomolybdic acid is a stain used in thin-layer chromatography
[{{cite web | title = Stains for Developing TLC Plates | url = https://www.chemistry.mcmaster.ca/adronov/resources/Stains_for_Developing_TLC_Plates.pdf | publisher = McMaster University}}] and trichrome staining in histochemistry.[{{cite journal |last1= Everett |first1= M.M. |last2= Miller |first2= W.A. |date= 1974 |title= The role of phosphotungstic and phosphomolybdic acids in connective tissue staining I. Histochemical studies |journal= The Histochemical Journal |volume= 6 |issue= 1 |pages= 25–34 |doi= 10.1007/BF01011535|pmid= 4130630 }}]
Biological role{{Main|Molybdenum in biology}}
Molybdenum, despite its low concentration in the environment, is a critically important element for Earth's biosphere due to its presence in the most common nitrogenases. Without molybdenum, nitrogen fixation would be greatly reduced, and a large part of biosynthesis as we know it would not occur. Molybdenum is also essential to many individual organisms as a component of enzymes, particularly as part of the molybdopterin class of cofactors. =Mo-containing enzymes=Molybdenum is an essential element in most organisms; a 2008 research paper speculated that a scarcity of molybdenum in the Earth's early oceans may have strongly influenced the evolution of eukaryotic life (which includes all plants and animals).[{{cite journal |last2=Lyons|first2=T. W. |last3=Bekker|first3=A.|last4=Shen|first4=Y. |last5=Poulton |first5=S. W. |last6=Chu |first6=X.|last7=Anbar|first7=A. D. |date=2008 |title=Tracing the stepwise oxygenation of the Proterozoic ocean |journal=Nature|volume=452|issue=7186 |pages=456–460 |bibcode=2008Natur.452..456S |doi=10.1038/nature06811 |pmid=18368114 |last1=Scott |first1=C.|s2cid=205212619 |doi-access= }}]
At least 50 molybdenum-containing enzymes have been identified, mostly in bacteria.[{{cite journal |title=Synthetic Analogues and Reaction Systems Relevant to the Molybdenum and Tungsten Oxotransferases |journal=Chem. Rev. |date=2004 |volume=104 |pages=1175–1200 |doi=10.1021/cr020609d |first1=John H. |last1=Enemark |first2=J. Jon A. |last2 =Cooney |first3=Jun-Jieh |last3=Wang |first4=R. H. |last4 =Holm |pmid=14871153 |issue=2}}][{{cite journal |doi=10.1016/j.bbamcr.2006.03.013 |pages=621–635 |pmid=16784786 |date=2006 |last1=Mendel |first1=Ralf R. |last2=Bittner |first2=Florian |title=Cell biology of molybdenum |journal=Biochimica et Biophysica Acta (BBA) - Molecular Cell Research |volume=1763 |issue=7}}] Those enzymes include aldehyde oxidase, sulfite oxidase and xanthine oxidase.[{{cite journal |title=The Mononuclear Molybdenum Enzymes |author=Russ Hille |author2=James Hall |author3=Partha Basu|journal=Chem. Rev. |year=2014 |volume=114 |issue=7 |pages=3963–4038 |doi=10.1021/cr400443z |pmid=24467397 |pmc=4080432}}]
In terms of function, molybdoenzymes catalyze the oxidation and sometimes reduction of certain small molecules in the process of regulating nitrogen, sulfur, and carbon.[{{cite journal |title=A structural comparison of molybdenum cofactor-containing enzymes |journal=FEMS Microbiol. Rev. |date=1999 |volume=22 |doi=10.1111/j.1574-6976.1998.tb00384.x |pmid=9990727 |issue=5 |pages=503–521 |last1=Kisker |first1=C. |last2=Schindelin |first2=H. |last3=Baas |first3=D. |last4=Rétey |first4=J. |last5=Meckenstock |first5=R. U. |last6=Kroneck |first6=P. M. H. |url=http://www.ioc.uni-karlsruhe.de/Professoren/Retey/fems_micro_reviews_1999_22_503.pdf |access-date=2017-10-25 |archive-url=https://web.archive.org/web/20170810025617/https://www.ioc.uni-karlsruhe.de/Professoren/Retey/fems_micro_reviews_1999_22_503.pdf |archive-date=2017-08-10 |url-status=live |doi-access=free}}] In some animals, and in humans, the oxidation of xanthine to uric acid, a process of purine catabolism, is catalyzed by xanthine oxidase, a molybdenum-containing enzyme. The activity of xanthine oxidase is directly proportional to the amount of molybdenum in the body. An extremely high concentration of molybdenum reverses the trend and can inhibit purine catabolism and other processes. Molybdenum concentration also affects protein synthesis, metabolism, and growth.
Mo is a component in most nitrogenases. Among molybdoenzymes, nitrogenases are unique in lacking the molybdopterin.[{{cite book]
|first1=Ralf R. |last1=Mendel
|editor1-first=Lucia |editor1-last=Banci |series=Metal Ions in Life Sciences |volume=12
|chapter= Chapter 15 Metabolism of Molybdenum
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|doi=10.1007/978-94-007-5561-10_15 |doi-broken-date=1 November 2024
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|editor2=Martha E. Sosa Torres
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Nitrogenases catalyze the production of ammonia from atmospheric nitrogen:
:
The biosynthesis of the FeMoco active site is highly complex.[{{cite journal|title = A newly discovered role for iron-sulfur clusters|first1 = Patricia C.| doi = 10.1073/pnas.0805713105| journal=PNAS| date=2008|volume=105|pages=11589–11590 |pmid = 18697949| last1 = Dos Santos|last2 = Dean|first2 = Dennis R.|issue = 33|pmc = 2575256|bibcode = 2008PNAS..10511589D |doi-access = free}}]
File:FeMoco cluster.svg active site of nitrogenase]]
File:Molybdenum cofactor.svg, which has bound an oxidized molybdenum(VI) atom through adjacent sulfur (or occasionally selenium) atoms. Except for the ancient nitrogenases, all known Mo-using enzymes use this cofactor.]]
Molybdate is transported in the body as MoO42−.[{{cite web |last=Mitchell |first=Phillip C. H. |title=Overview of Environment Database |publisher=International Molybdenum Association |date=2003 |url=http://hse.imoa.info/Default.asp?Page=110 |archive-url=https://web.archive.org/web/20071018005253/http://hse.imoa.info/Default.asp?Page=110 |archive-date=2007-10-18 |access-date=2007-05-05}}] = Excretion =Most molybdenum is excreted from the human body as molybdate in the urine. Furthermore, urinary excretion of molybdenum increases as dietary molybdenum intake increases. Small amounts of molybdenum are excreted from the body in the feces by way of the bile; small amounts also can be lost in sweat and in hair.[{{Cite book|last1=Gropper|first1=Sareen S.|url=https://books.google.com/books?id=9-C5DQAAQBAJ|title=Advanced Nutrition and Human Metabolism|last2=Smith|first2=Jack L.|last3=Carr|first3=Timothy P.|date=2016-10-05|publisher=Cengage Learning|isbn=978-1-337-51421-7|language=en}}][{{Cite journal|last1=Turnlund|first1=J. R.|last2=Keyes|first2=W. R.|last3=Peiffer|first3=G. L.|date=October 1995|title=Molybdenum absorption, excretion, and retention studied with stable isotopes in young men at five intakes of dietary molybdenum|journal=The American Journal of Clinical Nutrition|volume=62|issue=4|pages=790–796|doi=10.1093/ajcn/62.4.790|issn=0002-9165|pmid=7572711|doi-access=free}}] =Excess and copper antagonism=High levels of molybdenum can interfere with the body's uptake of copper, producing copper deficiency. Molybdenum prevents plasma proteins from binding to copper, and it also increases the amount of copper that is excreted in urine. Ruminants that consume high levels of molybdenum suffer from diarrhea, stunted growth, anemia, and achromotrichia (loss of fur pigment). These symptoms can be alleviated by copper supplements, either dietary and injection.[{{cite journal|last = Suttle|first = N. F.|title = Recent studies of the copper-molybdenum antagonism|journal = Proceedings of the Nutrition Society|volume = 33|issue = 3|pages = 299–305|date= 1974|doi = 10.1079/PNS19740053|pmid = 4617883|doi-access = free}}] The effective copper deficiency can be aggravated by excess sulfur.[Hauer, Gerald [http://www.bisoncentre.com/index.php?option=com_content&view=article&id=59&Itemid=256 Copper deficiency in cattle] {{Webarchive|url=https://web.archive.org/web/20110910172605/http://www.bisoncentre.com/index.php?option=com_content&view=article&id=59&Itemid=256 |date=2011-09-10 }}. Bison Producers of Alberta. Accessed Dec. 16, 2010.]
Copper reduction or deficiency can also be deliberately induced for therapeutic purposes by the compound ammonium tetrathiomolybdate, in which the bright red anion tetrathiomolybdate is the copper-chelating agent. Tetrathiomolybdate was first used therapeutically in the treatment of copper toxicosis in animals. It was then introduced as a treatment in Wilson's disease, a hereditary copper metabolism disorder in humans; it acts both by competing with copper absorption in the bowel and by increasing excretion. It has also been found to have an inhibitory effect on angiogenesis, potentially by inhibiting the membrane translocation process that is dependent on copper ions.[{{cite journal|author = Nickel, W|title = The Mystery of nonclassical protein secretion, a current view on cargo proteins and potential export routes|journal = Eur. J. Biochem.|date = 2003|volume = 270|pages = 2109–2119|doi = 10.1046/j.1432-1033.2003.03577.x|pmid=12752430|issue = 10|doi-access = free}}] This is a promising avenue for investigation of treatments for cancer, age-related macular degeneration, and other diseases that involve a pathologic proliferation of blood vessels.[{{cite journal|author=Brewer GJ|title=Treatment of Wilson disease with ammonium tetrathiomolybdate: III. Initial therapy in a total of 55 neurologically affected patients and follow-up with zinc therapy |journal=Arch Neurol |date=2003 |volume=60 |issue=3 |pages=379–85 |pmid=12633149 |doi=10.1001/archneur.60.3.379|last2=Hedera|first2=P.|last3=Kluin|first3=K. J.|last4=Carlson|first4=M.|last5=Askari|first5=F.|last6=Dick|first6=R. B.|last7=Sitterly|first7=J.|last8=Fink|first8=J. K.|doi-access=}}][{{cite journal|pmid=10656425|date=2000|last1=Brewer|first1=G. J.|last2=Dick|first2=R. D.|last3=Grover|first3=D. K.|last4=Leclaire|first4=V.|last5=Tseng|first5=M.|last6=Wicha|first6=M.|last7=Pienta|first7=K.|last8=Redman|first8=B. G.|last9=Jahan|first9=T.|last10=Sondak |first10=V. K.|last11=Strawderman |first11=M.|last12=LeCarpentier |first12=G.|last13=Merajver |first13=S. D.| title=Treatment of metastatic cancer with tetrathiomolybdate, an anticopper, antiangiogenic agent: Phase I study|volume=6|issue=1|pages=1–10|journal=Clinical Cancer Research}}]
In some grazing livestock, most strongly in cattle, molybdenum excess in the soil of pasturage can produce scours (diarrhea) if the pH of the soil is neutral to alkaline; see teartness. =Mammography=Molybdenum targets are used in mammography because they produce X-rays in the energy range of 17-20 keV, which is optimal for imaging soft tissues like the breast.[{{cite web |url=https://www.sputtertargets.net/blog/why-is-molybdenum-used-in-mammography-for-breast-cancer.html |title=Why is Molybdenum Target Used in Mammography for Breast Cancer? |last=Green |first=Julissa |website=Sputter Targets |access-date=Aug 2, 2024}}][{{cite book |year=2016 |title=IARC Working Group on the Evaluation of Cancer-Preventive Interventions: Breast cancer screening |publisher=Lyon (FR): International Agency for Research on Cancer |chapter=2. Screening Techniques |url=https://www.ncbi.nlm.nih.gov/books/NBK546557/ |access-date=Sep 2, 2024}}] The characteristic X-rays emitted from molybdenum provide high contrast between different types of tissues, allowing for the effective visualization of microcalcifications and other subtle abnormalities in breast tissue.[{{cite journal |first1=Qi-Hang |last1=Su |first2=Yan |last2=Zhang |year=2020 |title=Application of molybdenum target X-ray photography in imaging analysis of caudal intervertebral disc degeneration in rats |journal=World J Clin Cases |volume=8 |issue=6 |pages=3431–3439 |doi=10.12998/wjcc.v8.i16.3431 |doi-access=free |pmc=7457105 |pmid=32913849}}] This energy range also minimizes radiation dose while maximizing image quality, making molybdenum targets particularly suitable for breast cancer screening.[{{cite journal |first1=Khaled |last1=Alkhalifah |first2=Akram |last2=Asbeutah |year=2020 |title=Image Quality and Radiation Dose for Fibrofatty Breast using Target/filter Combinations in Two Digital Mammography Systems |journal=J Clin Imaging Sci |volume=10 |issue=56 |page=56 |doi=10.25259/JCIS_30_2020 |pmc=7533093 |pmid=33024611}}] Dietary recommendationsIn 2000, the then U.S. Institute of Medicine (now the National Academy of Medicine, NAM) updated its Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for molybdenum. If there is not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) is used instead.
An AI of 2 micrograms (μg) of molybdenum per day was established for infants up to 6 months of age, and 3 μg/day from 7 to 12 months of age, both for males and females. For older children and adults, the following daily RDAs have been established for molybdenum: 17 μg from 1 to 3 years of age, 22 μg from 4 to 8 years, 34 μg from 9 to 13 years, 43 μg from 14 to 18 years, and 45 μg for persons 19 years old and older. All these RDAs are valid for both sexes. Pregnant or lactating females from 14 to 50 years of age have a higher daily RDA of 50 μg of molybdenum.
As for safety, the NAM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of molybdenum, the UL is 2000 μg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).[{{cite book | last1 = Institute of Medicine | s2cid = 44243659 | title = Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc | chapter = Molybdenum | publisher = The National Academies Press | year = 2000 | location = Washington, DC | pages = 420–441 | chapter-url = https://www.nap.edu/read/10026/chapter/13| doi = 10.17226/10026 | pmid = 25057538 | isbn = 978-0-309-07279-3 | author1-link = Institute of Medicine }}]
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the United States. For women and men ages 15 and older, the AI is set at 65 μg/day. Pregnant and lactating women have the same AI. For children aged 1–14 years, the AIs increase with age from 15 to 45 μg/day. The adult AIs are higher than the U.S. RDAs,[{{cite web| title = Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies| year = 2017| url = https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf| access-date = 2017-09-10| archive-url = https://web.archive.org/web/20170828082247/https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf| archive-date = 2017-08-28| url-status = dead}}] but on the other hand, the European Food Safety Authority reviewed the same safety question and set its UL at 600 μg/day, which is much lower than the U.S. value.[{{citation| title = Tolerable Upper Intake Levels For Vitamins And Minerals| publisher = European Food Safety Authority| year = 2006| url = http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf| access-date = 2017-09-10| archive-url = https://web.archive.org/web/20160316225123/http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf| archive-date = 2016-03-16| url-status = dead}}] =Labeling=For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For molybdenum labeling purposes, 100% of the Daily Value was 75 μg, but as of May 27, 2016 it was revised to 45 μg.[{{cite web |url=https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf |title=Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels. FR page 33982. |access-date=September 10, 2017 |archive-url=https://web.archive.org/web/20160808164651/https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf |archive-date=August 8, 2016 |url-status=live }}][{{cite web | title=Daily Value Reference of the Dietary Supplement Label Database (DSLD) | website=Dietary Supplement Label Database (DSLD) | url=https://www.dsld.nlm.nih.gov/dsld/dailyvalue.jsp | access-date=16 May 2020 | archive-date=7 April 2020 | archive-url=https://web.archive.org/web/20200407073956/https://dsld.nlm.nih.gov/dsld/dailyvalue.jsp | url-status=dead }}] A table of the old and new adult daily values is provided at Reference Daily Intake. Food sourcesAverage daily intake varies between 120 and 240 μg/day, which is higher than dietary recommendations.[{{cite journal|doi=10.1007/BF01811327|title=The role of molybdenum in human biology|date=1983|last=Coughlan|first = M. P.|s2cid=10114173|journal=Journal of Inherited Metabolic Disease|volume=6|pages=70–77|pmid=6312191|issue=S1}}] Pork, lamb, and beef liver each have approximately 1.5 parts per million of molybdenum. Other significant dietary sources include green beans, eggs, sunflower seeds, wheat flour, lentils, cucumbers, and cereal grain. PrecautionsMolybdenum dusts and fumes, generated by mining or metalworking, can be toxic, especially if ingested (including dust trapped in the sinuses and later swallowed).[{{cite web|title = Material Safety Data Sheet – Molybdenum|publisher = The REMBAR Company, Inc.|date= 2000-09-19|url = http://www.rembar.com/MSDSmo.htm|access-date = 2007-05-13 |archive-url = https://web.archive.org/web/20070323103727/http://www.rembar.com/MSDSmo.htm |archive-date = March 23, 2007}}][{{cite web|title = Material Safety Data Sheet – Molybdenum Powder|publisher = CERAC, Inc.|date= 1994-02-23|url = http://asp.cerac.com/CatalogNet/default.aspx?p=msdsFile&msds=m000121.htm|archive-url = https://web.archive.org/web/20110708132733/http://asp.cerac.com/CatalogNet/default.aspx?p=msdsFile&msds=m000121.htm|archive-date = 2011-07-08|access-date = 2007-10-19}}] OSHA regulations specify the maximum permissible molybdenum exposure in an 8-hour day as 5 mg/m3. Chronic exposure to 60 to 600 mg/m3 can cause symptoms including fatigue, headaches and joint pains.[{{cite web|title = NIOSH Documentation for IDLHs Molybdenum|publisher = National Institute for Occupational Safety and Health|date = 1996-08-16|url = https://www.cdc.gov/niosh/idlh/moly-mo.html|access-date = 2007-05-31|archive-url = https://web.archive.org/web/20070807130614/http://www.cdc.gov/niosh/idlh/moly-mo.html|archive-date = 2007-08-07|url-status = live}}] At levels of 5000 mg/m3, molybdenum is immediately dangerous to life and health.[{{Cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Molybdenum|url = https://www.cdc.gov/niosh/npg/npgd0433.html|website = www.cdc.gov|access-date = 2015-11-20|archive-url = https://web.archive.org/web/20151120130010/http://www.cdc.gov/niosh/npg/npgd0433.html|archive-date = 2015-11-20|url-status = live}}] Bibliography
- {{Cite book |title=Lettera di Giulio Candida al signor Vincenzo Petagna – Sulla formazione del molibdeno |year=1785 |location=Naples |publisher=Giuseppe Maria Porcelli |url=https://archive.org/details/bub_gb_o_CjRnWqSNgC/page/n0 |ref=gcandida-molibdeno}}
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