Manganese#Chemical compounds

Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to melt, but easy to oxidize.{{cite book|publisher=Walter de Gruyter|date=1985|edition=91–100 |pages=1110–1117|isbn=978-3-11-007511-3|title=Lehrbuch der Anorganischen Chemie|first=Arnold F.|last=Holleman|author2=Wiberg, Egon|author3=Wiberg, Nils|language=de|chapter=Mangan}} Manganese and its common ions are paramagnetic.{{cite book |url=https://archive.org/details/crchandbookofche81lide |url-status=live |title=Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics |publisher=CRC press |isbn=978-0-8493-0485-9 |first=David R. |last=Lide |date=2004 |url-access=registration |access-date=7 September 2019 |page=4-136}} Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen.{{Britannica|id=361875|title=Manganese}}

{{Main|Isotopes of manganese}}

Naturally occurring manganese is composed of one stable isotope, ⁵⁵Mn. Several radioisotopes have been isolated and described, ranging in atomic weight from 46 u (⁴⁶Mn) to 72 u (⁷²Mn). The most stable are ⁵³Mn with a half-life of 3.7 million years, ⁵⁴Mn with a half-life of 312.2 days, and ⁵²Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. The primary decay mode in isotopes lighter than the most abundant stable isotope, ⁵⁵Mn, is electron capture, and the primary mode in heavier isotopes is beta decay. Manganese also has three meta states.{{NUBASE2016}}

Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion.{{cite web |url=https://www.science.org/content/article/galaxy-s-brightest-explosions-go-nuclear-unexpected-trigger-pairs-dead-stars |title=The galaxy's brightest explosions go nuclear with an unexpected trigger: pairs of dead stars |work=Science |last=Clery |first=Daniel |date=4 June 2020 |access-date=26 July 2021 }} ⁵³Mn decays to ⁵³Cr with a half-life of 3.7 million years. Because of its short half-life, ⁵³Mn is relatively rare; it is produced by the impact of cosmic rays on iron.{{cite journal |last1=Schaefer |first1=Jeorg|last2=Faestermann |first2=Thomas |title=Terrestrial manganese-53 – A new monitor of Earth surface processes |journal=Earth and Planetary Science Letters|volume=251|issue=3–4 |pages=334–345|date=2006 |doi=10.1016/j.epsl.2006.09.016 |bibcode=2006E&PSL.251..334S |last3=Herzog |first3=Gregory F. |last4=Knie |first4=Klaus |last5=Korschinek |first5=Gunther |last6=Masarik |first6=Jozef |last7=Meier |first7=Astrid |last8=Poutivtsev |first8=Michail |last9=Rugel |first9=Georg |last10=Schlüchter |first10=Christian |last11=Serifiddin |first11=Feride |last12=Winckler |first12=Gisela}} Manganese isotopic contents are typically combined with chromium isotopic contents and have found application in isotope geology and radiometric dating. Mn–Cr isotopic ratios reinforce the evidence from ²⁶Al and ¹⁰⁷Pd for the early history of the Solar System. Variations in ⁵³Cr/⁵²Cr and Mn/Cr ratios from several meteorites suggest an initial ⁵³Mn/⁵⁵Mn ratio, which indicate that Mn–Cr isotopic composition must result from in situ decay of ⁵³Mn in differentiated planetary bodies. Hence, ⁵³Mn provides additional evidence for nucleosynthetic processes immediately before the coalescence of the Solar System.{{Unbulleted list citebundle|{{cite journal|doi=10.1016/S0016-7037(99)00312-9 |title=53Mn-53Cr evolution of the early solar system|year=1999|last1=Birck|first1=J. |last2=Rotaru|last3=Allègre|journal=Geochimica et Cosmochimica Acta|volume=63|pages=4111–4117|first2=M.|first3=C.|bibcode=1999GeCoA..63.4111B |issue=23–24}}|{{cite journal |doi=10.1016/S0016-7037(98)00189-6|title=Early solar system timescales according to 53Mn-53Cr systematics |year=1998|last1=Lugmair |first1=G.|journal=Geochimica et Cosmochimica Acta|volume=62|pages=2863–2886|bibcode=1998GeCoA..62.2863L|issue=16 |last2=Shukolyukov |first2=A.}}|{{cite journal|doi=10.1023/A:1005243228503|title=On The 53Mn Heterogeneity In The Early Solar System|year=2000|last1=Shukolyukov|first1=Alexander|last2=Lugmair |journal=Space Science Reviews|volume=92|pages=225–236|first2=Günter W.|bibcode=2000SSRv...92..225S}}|{{cite journal |doi=10.1016/j.gca.2008.03.023|title=53Mn–53Cr systematics of the early Solar System revisited|year=2008|last1=Trinquier|first1=A. |last2=Birck|last3=Allègre|last4=Göpel|last5=Ulfbeck |journal=Geochimica et Cosmochimica Acta|volume=72|pages=5146–5163|first2=J.|first3=C. |first4=C.|first5=D.|bibcode=2008GeCoA..72.5146T |issue=20}}}}

Four allotropes (structural forms) of solid manganese are known, labeled α, β, γ and δ, and occur at successively higher temperatures. All are metallic, stable at standard pressure, and have a cubic crystal lattice, but they vary widely in their atomic structures.{{cite journal |last1=Young |first1=D.A. |title=Phase diagrams of the elements |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:7255152 |website=International Nuclear Information System |publisher=LNL |access-date=30 January 2023 |page=15 |date=1975}}{{cite book |last1=Dhananjayan |first1=N. |last2=Banerjee |first2=T. |title=Crystallographic modifications of manganese and their transformation characteristics. Chapter 1 of: Structure of Electro-Deposited Manganese. |date=1969 |pages=3–28 |publisher=CSIR-NML |url=https://eprints.nmlindia.org/5609/}}{{cite book | last1=Kemmitt | first1=R. D. W. | last2=Peacock | first2=R. D. | title=The Chemistry of Manganese, Technetium and Rhenium. Pergamon Texts in Inorganic Chemistry. | publisher=Elsevier Science | publication-place=Saint Louis | date=1973 | isbn=978-1-4831-3806-0 | oclc=961064866 | page=778}}

Alpha manganese (α-Mn) is the equilibrium phase at room temperature. It has a body-centered cubic lattice and is unusual among elemental metals in that it has a very complex unit cell, with 58 atoms per cell (29 atoms per primitive unit cell) with manganese atoms in four different types of surroundings (sites).{{cite journal | first1=A.J. | last1=Bradley | first2=J. | last2=Thewlis | title=The crystal structure of α-manganese | journal=Proceedings of the Royal Society of London, Series A | volume=115 | issue=771 | year=1927 | issn=0950-1207 | doi=10.1098/rspa.1927.0103 | pages=456–471| bibcode=1927RSPSA.115..456B | doi-access=free }} It is paramagnetic at room temperature and antiferromagnetic at temperatures below {{convert|95|K|C|sigfig=3}}.{{cite journal | last1=Lawson | first1=A. C. | last2=Larson | first2=Allen C. | last3=Aronson | first3=M. C. | display-authors=etal | title=Magnetic and crystallographic order in α-manganese | journal=J. Appl. Phys. | volume=76 | issue=10 | date=1994 | pages=7049–7051 | issn=0021-8979 | doi=10.1063/1.358024| bibcode=1994JAP....76.7049L }}

File:Phase diagram of manganese (1975).png

Beta manganese (β-Mn) forms when heated above the transition temperature of {{convert|973|K|C F|sigfig=3}}. It has a primitive cubic structure with 20 atoms per unit cell at two types of sites, which is as complex as that of any other elemental metal.{{cite journal | last1=Prior | first1=Timothy J | last2=Nguyen-Manh | first2=Duc | last3=Couper | first3=Victoria J | last4=Battle | first4=Peter D | title=Ferromagnetism in the beta-manganese structure: Fe_1.5Pd_0.5Mo₃N | journal=Journal of Physics: Condensed Matter | volume=16 | issue=13 | date=2004 | issn=0953-8984 | doi=10.1088/0953-8984/16/13/008 | pages=2273–2281| bibcode=2004JPCM...16.2273P | s2cid=250784683 }} It is easily obtained as a metastable phase at room temperature by rapid quenching of manganese at {{convert|850|C|K F|sigfig=3}} in ice water. It does not show magnetic ordering, remaining paramagnetic down to the lowest temperature measured (1.1 K).{{cite journal | last1=Funahashi | first1=S. | last2=Kohara | first2=T. | title=Neutron diffuse scattering in β-manganese | journal=J. Appl. Phys. | volume=55 | issue=6 | date=1984 | issn=0021-8979 | doi=10.1063/1.333561 | pages=2048–2050| bibcode=1984JAP....55.2048F }}{{cite journal | last1=Duschanek | first1=H. | last2=Mohn | first2=P. | last3=Schwarz | first3=K. | title=Antiferromagnetic and ferromagnetic gamma-manganese generalisation of the fixed-spin-moment method | journal=Physica B: Condensed Matter | volume=161 | issue=1–3 | year=1989 | issn=0921-4526 | doi=10.1016/0921-4526(89)90120-8 | pages=139–142}}

Gamma manganese (γ-Mn) forms when heated above {{convert|1370|K|C F|sigfig=3}}. It has a simple face-centered cubic structure (four atoms per unit cell). When quenched to room temperature it converts to β-Mn, but it can be stabilized at room temperature by alloying it with at least 5 percent of other elements (such as C, Fe, Ni, Cu, Pd or Au). These solute-stabilized alloys distort into a face-centered tetragonal structure.{{cite journal | last1=Bacon | first1=G E | last2=Cowlam | first2=N | title=A study of some alloys of gamma -manganese by neutron diffraction | journal=Journal of Physics C: Solid State Physics | volume=3 | issue=3 | date=1970| issn=0022-3719 | doi=10.1088/0022-3719/3/3/023 | pages=675–686| bibcode=1970JPhC....3..675B }}

Delta manganese (δ-Mn) forms when heated above {{convert|1406|K|C F|sigfig=3}} and is stable up to the manganese melting point of {{convert|1519|K|C F|sigfig=3}}. It has a body-centered cubic structure (two atoms per cubic unit cell).

File:Chlorid manganatý.JPG crystals – the pale pink color of Mn(II) salts is due to a spin-forbidden 3d transition.{{cite book|title=Shriver and Atkins' Inorganic Chemistry|date=2010|publisher=Oxford University Press|isbn=978-0-19-923617-6|chapter=Ch. 20}}]]

Common oxidation states of manganese are +2, +3, +4, +6, and +7, although all oxidation states from −3 to +7 have been observed. Manganese in oxidation state +7 is represented by salts of the intensely purple permanganate anion {{Chem2|MnO4-}}.{{sfn|Greenwood|Earnshaw|1997|pages=1042–1046}} Potassium permanganate is a commonly used laboratory reagent because of its oxidizing properties; it is used as a topical medicine (for example, in the treatment of fish diseases). Solutions of potassium permanganate were among the first stains and fixatives to be used in the preparation of biological cells and tissues for electron microscopy.{{cite journal |doi=10.1083/jcb.2.6.799 |last=Luft |first=J. H.|date=1956 |title=Permanganate – a new fixative for electron microscopy |journal=Journal of Biophysical and Biochemical Cytology |volume=2 |pages=799–802 |pmid=13398447 |issue=6 |pmc=2224005}}

Aside from various permanganate salts, Mn(VII) is represented by the unstable, volatile derivative Mn₂O₇. Oxyhalides (MnO₃F and MnO₃Cl) are powerful oxidizing agents. The most prominent example of Mn in the +6 oxidation state is the green anion manganate, [MnO₄]²⁻. Manganate salts are intermediates in the extraction of manganese from its ores. Compounds with oxidation states +5 are somewhat elusive, and often found associated to an oxide (O²⁻) or nitride (N³⁻) ligand.{{Unbulleted list citebundle|{{cite journal |doi=10.1021/ar400147y|title=Reactivity of Nitrido Complexes of Ruthenium(VI), Osmium(VI), and Manganese(V) Bearing Schiff Base and Simple Anionic Ligands |year=2014 |last1=Man |first1=Wai-Lun |last2=Lam |first2=William W. Y. |last3=Lau |first3=Tai-Chu |journal=Accounts of Chemical Research |volume=47 |issue=2 |pages=427–439 |pmid=24047467 }}|{{cite journal |doi=10.1021/ar700039y|title=Corrolazines: New Frontiers in High-Valent Metalloporphyrinoid Stability and Reactivity |year=2007 |last1=Goldberg |first1=David P. |journal=Accounts of Chemical Research |volume=40 |issue=7 |pages=626–634 |pmid=17580977 }}}} One example is the blue anion hypomanganate [MnO₄]³⁻.{{sfn|Greenwood|Earnshaw|1997|pages=1049–1051}}

Mn(IV) is somewhat enigmatic because it is common in nature but far rarer in synthetic chemistry. The most common Mn ore, pyrolusite, is MnO₂. It is the dark brown pigment of many cave drawings{{cite journal | doi=10.1038/srep22159 | title=Selection and Use of Manganese Dioxide by Neanderthals | year=2016 | last1=Heyes | first1=Peter J. | last2=Anastasakis | first2=Konstantinos | last3=De Jong | first3=Wiebren | last4=Van Hoesel | first4=Annelies | last5=Roebroeks | first5=Wil | last6=Soressi | first6=Marie | journal=Scientific Reports | volume=6 | page=22159 | pmid=26922901 | pmc=4770591 | bibcode=2016NatSR...622159H }} and is also a common ingredient in dry cell batteries.{{sfn|Greenwood|Earnshaw|1997|pages=1048}} Complexes of Mn(IV), such as in K₂[MnF₆], are known but are rarer than those of manganese in the lower oxidation states. Mn(IV)-OH complexes are an intermediate in some enzymes, including the oxygen-evolving center (OEC) in plants.{{sfn|Greenwood|Earnshaw|1997|pages=1056}}{{cite journal |doi=10.1021/cr4004874|title=Mn4Ca Cluster in Photosynthesis: Where and How Water is Oxidized to Dioxygen |year=2014 |last1=Yano |first1=Junko |last2=Yachandra |first2=Vittal |journal=Chemical Reviews |volume=114 |issue=8 |pages=4175–4205 |pmid=24684576 |pmc=4002066 }}

Simple derivatives of Mn³⁺ are rarely encountered but can be stabilized by suitably alkaline ligands. Manganese(III) acetate is an oxidant useful in organic synthesis. Solid compounds of manganese(III) are characterized by a strong purple-red color and a preference for distorted octahedral coordination resulting from the Jahn-Teller effect.{{Cite journal|journal=Struct Chem |date=2017 |volume=28 |pages=201–212 |doi=10.1007/s11224-016-0864-0 |title=An historic and scientific study of the properties of metal(III) tris-acetylacetonates |first1=Evrim |last1=Arslan |first2=Roger A. |last2=Lalancette |first3=Ivan |last3=Bernal|issue=1 |bibcode=2017StrCh..28..201A }} File:KMnO4 in H2O.jpg

A particularly common oxidation state for manganese in aqueous solution is +2, which has a pale pink color. Many manganese(II) compounds are known, such as the aquo complexes derived from manganese(II) sulfate (MnSO₄) and manganese(II) chloride (MnCl₂). This oxidation state is also seen in the mineral rhodochrosite (manganese(II) carbonate). Manganese(II) commonly exists with a high-spin ground state, with 5 unpaired electrons, because of its high pairing energy. There are no spin-allowed d–d transitions in manganese(II), which explain its faint color.{{Cite book|last1=Rayner-Canham |first1=Geoffrey |last2=Overton |first2=Tina |date=2003 |title=Descriptive Inorganic Chemistry |publisher=Macmillan |page=491 |isbn=0-7167-4620-4}}.

|-

| −2 || [Mn(1,5-COD)₂]²⁻

|-

| −1 || Pentacarbonylhydridomanganese

|-

| 0 || Dimanganese decacarbonyl

|-

| +1 || Methylcyclopentadienyl manganese tricarbonyl

|-

| +2 || Manganese(II) chloride, Manganese(II) carbonate, Manganese(II) oxide

|-

| +3 || Manganese(III) fluoride, Manganese(III) acetate, Manganese(III) oxide

|-

| +4 || Manganese dioxide

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| +5 || Potassium hypomanganate

|-

| +6 || Potassium manganate

|-

| +7 || Potassium permanganate, Manganese heptoxide

|-

|colspan=2 style="font-size: smaller; text-align: center"|Common oxidation states are in bold.

|}

{{main|Organomanganese chemistry}}

Manganese forms a large variety of organometallic derivatives, i.e., compounds with Mn-C bonds. The organometallic derivatives include numerous examples of Mn in its lower oxidation states, i.e. Mn(−III) up through Mn(I). This area of organometallic chemistry is attractive because Mn is inexpensive and of relatively low toxicity.{{cite journal |doi=10.1021/acs.inorgchem.9b00941 |title=Resurgence of Organomanganese(I) Chemistry. Bidentate Manganese(I) Phosphine–Phenol(ate) Complexes |date=2019 |last1=Kadassery |first1=Karthika J. |last2=MacMillan |first2=Samantha N. |last3=Lacy |first3=David C. |journal=Inorganic Chemistry |volume=58 |issue=16 |pages=10527–10535 |pmid=31247867 }}

Of greatest commercial interest is methylcyclopentadienyl manganese tricarbonyl (MMT), which is used as an anti-knock compound added to gasoline in some countries, featuring Mn(I). Consistent with other aspects of Mn(II) chemistry, manganocene ({{chem2|Mn(C5H5)2}}) is high-spin. In contrast, its neighboring metal, iron, forms an air-stable, low-spin derivative in the form of ferrocene ({{chem2|Fe(C5H5)2}}). When conducted under an atmosphere of carbon monoxide, reduction of Mn(II) salts gives dimanganese decacarbonyl {{chem2|Mn2(CO)10}}, an orange and volatile solid. The air-stability of this Mn(0) compound (and its many derivatives) reflects the powerful electron-acceptor properties of carbon monoxide. Many alkene complexes and alkyne complexes are derived from {{chem2|Mn2(CO)10}}.{{sfn|Greenwood|Earnshaw|1997|pages=1062-1069}}

In Mn(CH₃)₂(dmpe)₂, Mn(II) is low spin, which contrasts with the high spin character of its precursor, MnBr₂(dmpe)₂ (dmpe = (CH₃)₂PCH₂CH₂P(CH₃)₂).{{cite journal |doi=10.1021/ja00360a054|title=Hydrido, alkyl, and ethylene 1,2-bis(dimethylphosphino)ethane complexes of manganese and the crystal structures of MnBr2(dmpe)2, [Mn(AlH4)(dmpe)2]2 and MnMe2(dmpe)2 |year=1983 |last1=Girolami |first1=Gregory S. |last2=Wilkinson |first2=Geoffrey |last3=Thornton-Pett |first3=Mark |last4=Hursthouse |first4=Michael B. |journal=Journal of the American Chemical Society |volume=105 |issue=22 |pages=6752–6753 |bibcode=1983JAChS.105.6752G }} Polyalkyl and polyaryl derivatives of manganese often exist in higher oxidation states, reflecting the electron-releasing properties of alkyl and aryl ligands. One example is [Mn(CH₃)₆]²⁻.{{cite journal |author1=Robert J. Morris |author2=Gregory S. Girolami |title=Permethylmanganates. Synthesis and characterization of divalent [MnMe₄^2-], trivalent [MnMe₅^2-], and tetravalent [MnMe₆^2-] |journal=Journal of the American Chemical Society |date=1988 |volume=110 |issue=18 |pages=6245–6246 |doi=10.1021/ja00226a049 |publisher=ACS Publications |pmid=22148809 |bibcode=1988JAChS.110.6245M |language=en}}

The origin of the name manganese is complex. In ancient times, two black minerals were identified from the regions of the Magnetes (either Magnesia, located within modern Greece, or Magnesia ad Sipylum, located within modern Turkey).{{cite web |last1=languagehat |title=MAGNET. |url=http://languagehat.com/magnet/ |website=languagehat.com |access-date=18 June 2020 |language=en |date=28 May 2005}} They were both called magnes from their place of origin, but were considered to differ in sex. The male magnes attracted iron, and was the iron ore now known as lodestone or magnetite, and which probably gave us the term magnet. The female magnes ore did not attract iron, but was used to decolorize glass. This female magnes was later called magnesia, known now in modern times as pyrolusite or manganese dioxide.{{Cite book |last=Pliny the Elder |url=https://www.gutenberg.org/cache/epub/62704/pg62704-images.html |title=Natural History of Pliny. BOOK XXXVI. THE NATURAL HISTORY OF STONES. |chapter=Chapter 25—THE MAGNET: THREE REMEDIES |author-link=Pliny the Elder}} Neither this mineral nor elemental manganese is magnetic. In the 16th century, manganese dioxide was called manganesum (note the two Ns instead of one) by glassmakers, possibly as a corruption and concatenation of two words, since alchemists and glassmakers eventually had to differentiate a magnesia nigra (the black ore) from magnesia alba (a white ore, also from Magnesia, also useful in glassmaking). Italian physician Michele Mercati called magnesia nigra manganesa, and finally the metal isolated from it became known as manganese ({{Langx|de|Mangan}}). The name magnesia was eventually used to refer only to the white magnesia alba (magnesium oxide), which provided the name magnesium for the free element when it was isolated much later.{{cite web|last=Calvert|first=J. B.|url=http://mysite.du.edu/~jcalvert/phys/chromang.htm|title=Chromium and Manganese|access-date=10 December 2022|date=24 January 2003|url-status=dead|archive-url=https://web.archive.org/web/20161231161307/http://mysite.du.edu/~jcalvert/phys/chromang.htm|archive-date=31 December 2016}}

File:Lascaux painting.jpg, France, use manganese-based pigments.{{cite journal|doi=10.1088/0957-0233/14/9/310|title=Analysis of rock art painting and technology of Palaeolithic painters|date=2003|last=Chalmin|first=Emilie |author2=Menu, Michel |author3=Vignaud, Colette|journal=Measurement Science and Technology|volume=14|pages=1590–1597|issue=9|s2cid=250842390 }}]]

Manganese dioxide, which is abundant in nature, has long been used as a pigment. The cave paintings in Gargas that are 30,000 to 24,000 years old are made from the mineral form of MnO₂ pigments.{{cite journal|doi=10.1007/s00339-006-3510-7|title=Minerals discovered in paleolithic black pigments by transmission electron microscopy and micro-X-ray absorption near-edge structure|date=2006|last1=Chalmin|first1=E.|last2=Vignaud|first2=C. |last3=Salomon|first3=H.|last4=Farges|first4=F.|last5=Susini|first5=J. |last6= Menu|first6=M.|journal=Applied Physics A|volume=83 |pages=213–218|issue=12|bibcode=2006ApPhA..83..213C|hdl=2268/67458|s2cid=9221234|url=http://orbi.ulg.ac.be/bitstream/2268/67458/1/fulltext.pdf}}

Manganese compounds were used by Egyptian and Roman glassmakers, either to add to, or remove, color from glass.{{cite journal |doi=10.1126/science.133.3467.1824|date=1961|last=Sayre|first=E. V.|author2=Smith, R. W.|title=Compositional Categories of Ancient Glass |volume=133|issue=3467|pages=1824–1826|journal=Science|pmid=17818999|bibcode=1961Sci...133.1824S|s2cid=25198686}} Use as "glassmakers soap" continued through the Middle Ages until modern times and is evident in 14th-century glass from Venice.

File:Gahn Johan Gottlieb.jpg.]]

Because it was used in glassmaking, manganese dioxide was available for experiments by alchemists, the first chemists. Ignatius Gottfried Kaim (1770) and Johann Glauber (17th century) discovered that manganese dioxide could be converted to permanganate, a useful laboratory reagent.{{cite journal|journal=Centaurus|volume=19|issue=4|title=The Discovery of an Element|first=E.|last=Rancke-Madsen|doi=10.1111/j.1600-0498.1975.tb00329.x|pages=299–313|date=1975|bibcode=1975Cent...19..299R}} By the mid-18th century, the Swedish chemist Carl Wilhelm Scheele used manganese dioxide to produce chlorine. First, hydrochloric acid, or a mixture of dilute sulfuric acid and sodium chloride was made to react with manganese dioxide, and later hydrochloric acid from the Leblanc process was used and the manganese dioxide was recycled by the Weldon process.{{cite book |author1=Peter Schmittinger |author2=Thomas Florkiewicz |author3=L. Calvert Curlin |author4=Benno Lüke |author5=Robert Scannell |author6=Thomas Navin |author7=Erich Zelfel |author8=Rüdiger Bartsch |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |isbn=9783527306732 |page=532 |language=en |chapter=Chlorine |doi = 10.1002/14356007.a06_399.pub3}}

Scheele and others were aware that pyrolusite (mineral form of manganese dioxide) contained a new element. Johan Gottlieb Gahn isolated an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon.{{cite journal |title=The metal manganese and its properties: also ores, and the production of ferro-manganese and its history |first=Robert |last=Hadfield |date=1927 |journal=The Journal of the Iron and Steel Institute |volume=115 |number=1 |pages=251–252 |url=https://books.google.com/books?id=aNVnjpEKb_oC&pg=PA251}} Ignatius Gottfried Kaim also may have reduced manganese dioxide to isolate the metal, but that is uncertain.{{cite journal |last1=Miśkowiec |first1=Paweł |date=2022 |title=Name game: the naming history of the chemical elements—part 1—from antiquity till the end of 18th century |journal=Foundations of Chemistry |volume= 25|issue= |pages= 29–51|doi=10.1007/s10698-022-09448-5 |doi-access=free }}{{cite web |title=Braunstein |url=https://www.mindat.org/min-40120.html |website=mindat.org |publisher=Mindat |access-date=23 April 2025}}

The manganese content of some iron ores used in Greece led to speculations that steel produced from that ore contains additional manganese, making the Spartan steel exceptionally hard.{{cite journal|doi=10.1002/ajim.20524|date=2007|title=From lead to manganese through mercury: mythology, science, and lessons for prevention|volume=50|issue=11|pages=779–787 |journal=American Journal of Industrial Medicine|pmid=17918211|last1=Alessio|first1=L.|last2=Campagna|first2=M.|last3=Lucchini|first3=R.}} Around the beginning of the 19th century, manganese was used in steelmaking and several patents were granted. In 1816, it was documented that iron alloyed with manganese was harder but not more brittle. In 1837, British academic James Couper noted an association between miners' heavy exposure to manganese and a form of Parkinson's disease.{{Cite journal |last=Blanc |first=Paul D. |date=2018 |title=The early history of manganese and the recognition of its neurotoxicity, 1837–1936 |url=https://linkinghub.elsevier.com/retrieve/pii/S0161813X17300657 |journal=NeuroToxicology |language=en |volume=64 |pages=5–11 |doi=10.1016/j.neuro.2017.04.006|bibcode=2018NeuTx..64....5B }} In 1912, United States patents were granted for protecting firearms against rust and corrosion with manganese phosphate electrochemical conversion coatings, and the process has seen widespread use ever since.{{cite book|title=Production of Manganese Ferroalloys|publisher=Tapir Academic Press |date=2007|isbn=978-82-519-2191-6|chapter=History of omanganese|pages=11–12|author=Olsen, Sverre E.|author2=Tangstad, Merete |author3=Lindstad, Tor}}

The invention of the Leclanché cell in 1866 and the subsequent improvement of batteries containing manganese dioxide as cathodic depolarizer increased the demand for manganese dioxide. Until the development of batteries with nickel–cadmium and lithium, most batteries contained manganese. The zinc–carbon battery and the alkaline battery normally use industrially produced manganese dioxide because naturally occurring manganese dioxide contains impurities. In the 20th century, manganese dioxide was widely used as the cathode for commercial disposable dry batteries of both the standard (zinc–carbon) and alkaline types.{{cite journal|doi=10.1002/ciuz.19800140502|title=Moderne Verfahren der Großchemie: Braunstein |date=1980|last=Preisler|first=Eberhard|journal=Chemie in unserer Zeit|language=de|volume=14|pages=137–148|issue=5}}

Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. This application was first recognized by the British metallurgist Robert Forester Mushet (1811–1891), who introduced the element to the steel manufacture process in 1856 in the form of spiegeleisen.{{Cite web |archive-url=https://web.archive.org/web/20180402225736/http://youle.info/history/fh_material/Making_of_Sheffield/13-LIVES.TXT |archive-date=2 April 2018 |url-status=usurped |url=http://youle.info/history/fh_material/Making_of_Sheffield/13-LIVES.TXT |title=SHEFFIELD'S LIFE STORIES. |access-date=2 April 2018}}

{{See also|Category:Manganese minerals}}

Manganese comprises about 1000 ppm (0.1%) of the Earth's crust and is the 12th most abundant element.{{cite book|title=Nature's Building Blocks: An A-Z Guide to the Elements|last=Emsley|first=John|publisher=Oxford University Press|date=2001|location=Oxford, UK|isbn=978-0-19-850340-8|chapter=Manganese|pages=[https://archive.org/details/naturesbuildingb0000emsl/page/249 249–253]|chapter-url=https://books.google.com/books?id=j-Xu07p3cKwC|url=https://archive.org/details/naturesbuildingb0000emsl/page/249}} Soil contains 7–9000 ppm of manganese with an average of 440 ppm. The atmosphere contains 0.01 μg/m³. Manganese occurs principally as pyrolusite (MnO₂), braunite (Mn²⁺Mn³⁺₆)SiO₁₂),{{cite journal|pages=65–71 |journal=Contributions to Mineralogy and Petrology|title=Geochemistry of braunite and associated phases in metamorphosed non-calcareous manganese ores of India|first=P. K.|last=Bhattacharyya|author2=Dasgupta, Somnath |author3=Fukuoka, M. |author4=Roy Supriya |doi=10.1007/BF00371403|date=1984|volume=87|issue=1|bibcode=1984CoMP...87...65B|s2cid=129495326}} psilomelane {{chem2|(Ba,H2O)2Mn5O10}}, and to a lesser extent as rhodochrosite (MnCO₃).

File:World Manganese Production 2006.svg

The most important manganese ore is pyrolusite (MnO₂). Other economically important manganese ores usually show a close spatial relation to the iron ores, such as sphalerite.{{Cite journal|last1=Cook|first1=Nigel J.|last2=Ciobanu|first2=Cristiana L.|last3=Pring|first3=Allan|last4=Skinner|first4=William|last5=Shimizu|first5=Masaaki|last6=Danyushevsky|first6=Leonid|last7=Saini-Eidukat|first7=Bernhardt|last8=Melcher|first8=Frank|date=2009|title=Trace and minor elements in sphalerite: A LA-ICPMS study|url=https://linkinghub.elsevier.com/retrieve/pii/S0016703709003263|journal=Geochimica et Cosmochimica Acta|language=en|volume=73|issue=16|pages=4761–4791|doi=10.1016/j.gca.2009.05.045|bibcode=2009GeCoA..73.4761C}} Land-based resources are large but irregularly distributed. About 80% of the known world manganese resources are in South Africa; other important manganese deposits are in Ukraine, Australia, India, China, Gabon and Brazil.

Manganese is mainly mined in South Africa, Australia, China, Gabon, Brazil, India, Kazakhstan, Ghana, Ukraine and Malaysia.{{Cite journal|doi = 10.1007/s11837-018-2769-4|title = Review of Manganese Processing for Production of TRIP/TWIP Steels, Part 1: Current Practice and Processing Fundamentals|journal = JOM |volume = 70|issue = 5|pages = 680–690|year = 2018|last1 = Elliott|first1 = R|last2 = Coley|first2 = K|last3 = Mostaghel|first3 = S|last4 = Barati|first4 = M|bibcode = 2018JOM....70e.680E|s2cid = 139950857}} In South Africa, most identified deposits are located near Hotazel in the Northern Cape Province, (Kalahari manganese fields), with a 2011 estimate of 15 billion tons. In 2011 South Africa produced 3.4 million tons, topping all other nations.{{cite web |url=http://www.mbendi.com/indy/ming/mang/af/sa/p0005.htm |title=Manganese Mining in South Africa – Overview |publisher=MBendi Information Services |access-date=10 December 2022 |url-status=dead |archive-url=https://web.archive.org/web/20160205194737/http://www.mbendi.com/indy/ming/mang/af/sa/p0005.htm |archive-date=5 February 2016}}

{{Main|Manganese nodule}}

An abundant resource of manganese in the form of manganese nodules found on the ocean floor.{{cite book |last1=Hein |first1=James R. |title=Encyclopedia of Marine Geosciences - Manganese Nodules |date=January 2016 |publisher=Springer |pages=408–412 |url=https://www.researchgate.net/publication/306107551 |access-date=2 February 2021}} These nodules, which are composed of 29% manganese,{{cite web |last1=International Seabed Authority |title=Polymetallic Nodules |url=https://isa.org.jm/files/files/documents/eng7.pdf |website=isa.org |publisher=International Seabed Authority |access-date=2 February 2021 |archive-date=23 October 2021 |archive-url=https://web.archive.org/web/20211023145629/https://isa.org.jm/files/files/documents/eng7.pdf |url-status=dead }} are located along the ocean floor. The environmental impacts of nodule collection are of interest.{{Cite journal|last1=Oebius|first1=Horst U|last2=Becker|first2=Hermann J|last3=Rolinski|first3=Susanne|last4=Jankowski|first4=Jacek A|date=January 2001|title=Parametrization and evaluation of marine environmental impacts produced by deep-sea manganese nodule mining|url=http://dx.doi.org/10.1016/s0967-0645(01)00052-2|journal=Deep Sea Research Part II: Topical Studies in Oceanography|volume=48|issue=17–18|pages=3453–3467|doi=10.1016/s0967-0645(01)00052-2|bibcode=2001DSRII..48.3453O|issn=0967-0645}}{{cite journal |last1=Thompson |first1=Kirsten F. |last2=Miller |first2=Kathryn A. |last3=Currie |first3=Duncan |last4=Johnston |first4=Paul |last5=Santillo |first5=David |title=Seabed Mining and Approaches to Governance of the Deep Seabed |journal=Frontiers in Marine Science |date=2018 |volume=5 |page=480 |doi=10.3389/fmars.2018.00480 |s2cid=54465407 |doi-access=free |bibcode=2018FrMaS...5..480T |hdl=10871/130176 |hdl-access=free }} According to 1978 estimate, the ocean floor has 500 billion tons of manganese nodules.{{cite journal|doi=10.1016/j.micron.2008.10.005|pages=350–358|date=2009|title=Manganese/polymetallic nodules: micro-structural characterization of exolithobiontic- and endolithobiontic microbial biofilms by scanning electron microscopy|volume=40 |issue=3|pmid=19027306|journal=Micron |author1=Wang, X|author2=Schröder, HC|author3=Wiens, M|author4=Schlossmacher, U|author5=Müller, WEG}} {{As of|2025|April}}, attempts to find economically viable methods of harvesting manganese nodules are still ongoing, however, none has been commercialized.{{Cite web |title=Exploration Contracts |url=https://www.isa.org.jm/exploration-contracts/ |access-date=4 April 2025 |publisher=International Seabed Authority|date=17 March 2022 }}

In 1972, the CIA's Project Azorian, through billionaire Howard Hughes, commissioned the ship Hughes Glomar Explorer with the cover story of harvesting manganese nodules from the sea floor.{{Cite news|url=https://www.bbc.com/news/science-environment-42994812|title=The CIA secret on the ocean floor|date=19 February 2018|work=BBC News|access-date=3 May 2018|language=en-GB}} This cover story triggered a rush of activity to collect manganese nodules. The real mission of Hughes Glomar Explorer was to raise a sunken Soviet submarine, the K-129, with the goal of retrieving Soviet code books.{{cite web |url=http://www2.gwu.edu/~nsarchiv/nukevault/ebb305/index.htm |title=Project Azorian: The CIA's Declassified History of the Glomar Explorer |publisher=National Security Archive at George Washington University |date=12 February 2010 |access-date=18 September 2013}}

Manganese also occurs in the oceanic environment, as dissolved manganese (dMn), which is found throughout the world's oceans, 90% of which originates from hydrothermal vents.{{Cite journal|last1=Hernroth|first1=Bodil|last2=Tassidis|first2=Helena|last3=Baden|first3=Susanne P.|date=March 2020|title=Immunosuppression of aquatic organisms exposed to elevated levels of manganese: From global to molecular perspective|url=http://dx.doi.org/10.1016/j.dci.2019.103536|journal=Developmental & Comparative Immunology|volume=104|pages=103536|doi=10.1016/j.dci.2019.103536|pmid=31705914|s2cid=207935992|issn=0145-305X}} Particulate Mn develops in buoyant plumes over an active vent source, while the dMn behaves conservatively.{{Cite journal|last1=Ray|first1=Durbar|last2=Babu|first2=E. V. S. S. K.|last3=Surya Prakash|first3=L.|date=1 January 2017|title=Nature of Suspended Particles in Hydrothermal Plume at 3°40'N Carlsberg Ridge:A Comparison with Deep Oceanic Suspended Matter|journal=Current Science|volume=112|issue=1|pages=139|doi=10.18520/cs/v112/i01/139-146 |issn=0011-3891|doi-access=free}} Mn concentrations vary between the water columns of the ocean. At the surface, dMn is elevated due to input from external sources such as rivers, dust, and shelf sediments. Coastal sediments normally have lower Mn concentrations, but can increase due to anthropogenic discharges from industries such as mining and steel manufacturing, which enter the ocean from river inputs. Surface dMn concentrations can also be elevated biologically through photosynthesis and physically from coastal upwelling and wind-driven surface currents. Internal cycling such as photo-reduction from UV radiation can also elevate levels by speeding up the dissolution of Mn-oxides and oxidative scavenging, preventing Mn from sinking to deeper waters.{{Cite journal|last1=Sim|first1=Nari|last2=Orians|first2=Kristin J.|date=October 2019|title=Annual variability of dissolved manganese in Northeast Pacific along Line-P: 2010–2013|url=http://dx.doi.org/10.1016/j.marchem.2019.103702|journal=Marine Chemistry|volume=216|pages=103702|doi=10.1016/j.marchem.2019.103702|bibcode=2019MarCh.21603702S |s2cid=203151735|issn=0304-4203}} Elevated levels at mid-depths can occur near mid-ocean ridges and hydrothermal vents. The hydrothermal vents release dMn enriched fluid into the water. The dMn can then travel up to 4,000 km due to the microbial capsules present, preventing exchange with particles, lowing the sinking rates. Dissolved Mn concentrations are even higher when oxygen levels are low. Overall, dMn concentrations are normally higher in coastal regions and decrease when moving offshore.

Manganese occurs in soils in three oxidation states: the divalent cation, Mn²⁺ and as brownish-black oxides and hydroxides containing Mn (III,IV), such as MnOOH and MnO₂. Soil pH and oxidation-reduction conditions affect which of these three forms of Mn is dominant in a given soil. At pH values less than 6 or under anaerobic conditions, Mn(II) dominates, while under more alkaline and aerobic conditions, Mn(III,IV) oxides and hydroxides predominate. These effects of soil acidity and aeration state on the form of Mn can be modified or controlled by microbial activity. Microbial respiration can cause both the oxidation of Mn²⁺ to the oxides, and it can cause reduction of the oxides to the divalent cation.{{Cite book|last1=Bartlett|first1=Richmond|title=Chemical Processes in Soils|last2=Ross|first2=Donald|publisher=Soil Science Society of America|year=2005|editor-last=Tabatabai|editor-first=M.A.|series=SSSA Book Series, no. 8|location=Madison, Wisconsin|pages=461–487|chapter=Chemistry of Redox Processes in Soils|lccn=2005924447|editor-last2=Sparks|editor-first2=D.L.}}

The Mn(III,IV) oxides exist as brownish-black stains and small nodules on sand, silt, and clay particles. These surface coatings on other soil particles have high surface area and carry negative charge. The charged sites can adsorb and retain various cations, especially heavy metals (e.g., Cr³⁺, Cu²⁺, Zn²⁺, and Pb²⁺). In addition, the oxides can adsorb organic acids and other compounds. The adsorption of the metals and organic compounds can then cause them to be oxidized while the Mn(III,IV) oxides are reduced to Mn²⁺ (e.g., Cr³⁺ to Cr(VI) and colorless hydroquinone to tea-colored quinone polymers).{{Cite book|last1=Dixon|first1=Joe B.|title=Soil Mineralogy with Environmental Applications|last2=White|first2=G. Norman|publisher=Soil Science Society of America|year=2002|editor-last=Dixon|editor-first=J.B.|series=SSSA Book Series no. 7|location=Madison, Wisconsin|pages=367–386|chapter=Manganese Oxides|lccn=2002100258|editor-last2=Schulze|editor-first2=D.G.}}

{{see also|Manganese production by country}}

A significant proportion of the manganese ore mined, around 85% in the United States, is used in iron and steel production, such as in the production of ferromanganese.{{cite web |author1=Ji-Eun Kim |title=Manganese Statistics and Information |url=https://www.usgs.gov/centers/national-minerals-information-center/manganese-statistics-and-information |website=USGS |publisher=National Minerals Information Center |access-date=23 April 2025 |language=en}} For the production of ferromanganese, the manganese ore is mixed with iron ore and carbon, and then reduced either in a blast furnace or in an electric arc furnace.{{cite book|title=Industrial Minerals & Rocks: Commodities, Markets, and Uses |edition=7th|publisher=SME|date=2006|isbn=978-0-87335-233-8|chapter=Manganese|first=L. A.|last=Corathers |author2=Machamer, J. F. |chapter-url=https://books.google.com/books?id=zNicdkuulE4C&pg=PA631|pages=631–636}} The resulting ferromanganese has a manganese content of 30–80%. Pure manganese used for the production of iron-free alloys is produced by leaching manganese ore with sulfuric acid and a subsequent electrowinning process.{{cite journal|doi=10.1016/j.hydromet.2007.08.010 |title=Manganese metallurgy review. Part I: Leaching of ores/secondary materials and recovery of electrolytic/chemical manganese dioxide|date=2007|last=Zhang|first=Wensheng|author2=Cheng, Chu Yong|journal=Hydrometallurgy|volume=89 |pages=137–159|issue=3–4|bibcode=2007HydMe..89..137Z }}

File:Manganese Process Flow Diagram.jpg

A more progressive extraction process involves directly reducing (a low grade) manganese ore by heap leaching. This is done by percolating natural gas through the bottom of the heap; the natural gas provides the heat (needs to be at least 850 °C) and the reducing agent (carbon monoxide). This reduces all of the manganese ore to manganese oxide (MnO), which is a leachable form. The ore then travels through a grinding circuit to reduce the particle size of the ore to between 150 and 250 μm, increasing the surface area to aid leaching. The ore is then added to a leach tank of sulfuric acid and ferrous iron (Fe²⁺) in a 1.6:1 ratio. The iron reacts with the manganese dioxide (MnO₂) to form iron hydroxide (FeO(OH)) and elemental manganese (Mn).

This process yields greater than 90% recovery of the manganese. For further purification, the manganese can then be sent to an electrowinning facility.{{cite web|url=http://www.americanmanganeseinc.com/wp-content/uploads/2011/08/American-Manganese-Phase-II-August-19-2010-Final-Report-Internet-Version-V2.pdf|title=The Recovery of Manganese from low grade resources: bench scale metallurgical test program completed|date=2010|author=Chow, Norman|author2=Nacu, Anca|author3=Warkentin, Doug|author4=Aksenov, Igor|author5=Teh, Hoe|name-list-style=amp|publisher=Kemetco Research Inc.|url-status=dead|archive-url=https://web.archive.org/web/20120202065633/http://www.americanmanganeseinc.com/wp-content/uploads/2011/08/American-Manganese-Phase-II-August-19-2010-Final-Report-Internet-Version-V2.pdf|archive-date=2 February 2012}}

File:M1917helmet.jpg, a variant of Brodie helmet, made from Hadfield steel manganese alloy]]

Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties. Manganese has no satisfactory substitute in these applications in metallurgy. Steelmaking,{{cite book|isbn=978-0-87170-858-8|pages=56–57|first=John D. |last=Verhoeven |date=2007 |publisher=ASM International |location=Materials Park, Ohio |title=Steel metallurgy for the non-metallurgist}} including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Manganese is a key component of low-cost stainless steel.Manganese USGS 2006{{cite journal |doi=10.1007/BF02648339 |title=Mechanism of work hardening in Hadfield manganese steel |date=1981 |last1=Dastur|first1=Y. N. |journal=Metallurgical Transactions A|volume=12|pages=749–759|last2=Leslie|first2=W. C.|issue=5|bibcode=1981MTA....12..749D|s2cid=136550117}} Often ferromanganese (usually about 80% manganese) is the intermediate in modern processes.

Small amounts of manganese improve the workability of steel at high temperatures by forming a high-melting sulfide and preventing the formation of a liquid iron sulfide at the grain boundaries. If the manganese content reaches 4%, the embrittlement of the steel becomes a dominant feature. The embrittlement decreases at higher manganese concentrations and reaches an acceptable level at 8%. Steel containing 8 to 15% of manganese has a high tensile strength of up to 863 MPa.{{cite book|isbn=978-1-4086-2616-0 |pages=351–352|title=Iron and Steel|first=John Henry |last=Stansbie|publisher=Read Books|url=https://books.google.com/books?id=FyogLqUxW1cC&pg=PA351 |date=2007}}{{cite book|isbn=978-0-07-136076-0|pages=585–587|last=Brady|first=George S.|author2=Clauser, Henry R. |author3=Vaccari. John A. |date=2002|publisher=McGraw-Hill|location=New York, NY|title=Materials Handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors|url=https://books.google.com/books?id=vIhvSQLhhMEC&pg=PA585}} Steel with 12% manganese was discovered in 1882 by Robert Hadfield and is still known as Hadfield steel (mangalloy). It was used for British military steel helmets and later by the U.S. military.{{cite journal|title=Sir Robert Abbott Hadfield F.R.S. (1858–1940), and the Discovery of Manganese Steel Geoffrey Tweedale|journal=Notes and Records of the Royal Society of London|volume=40|issue=1 |date=1985|pages=63–74|doi=10.1098/rsnr.1985.0004|first=Geoffrey|last=Tweedale|jstor=531536|s2cid=73176861 |doi-access=}}

{{Main|Aluminium alloy}}

Manganese is used in production of alloys with aluminium. Aluminium with roughly 1.5% manganese has increased resistance to corrosion through grains that absorb impurities which would lead to galvanic corrosion.{{cite web |url=http://www.suppliersonline.com/propertypages/2024.asp|title=Chemical properties of 2024 aluminum allow|access-date=30 April 2009 |publisher=Metal Suppliers Online, LLC.}} The corrosion-resistant aluminium alloys 3004 and 3104 (0.8 to 1.5% manganese) are used for most beverage cans.{{cite book |title=Introduction to aluminum alloys and tempers|first=John Gilbert |last=Kaufman|publisher=ASM International|date=2000|isbn=978-0-87170-689-8|chapter=Applications for Aluminium Alloys and Tempers |pages=93–94|chapter-url=https://books.google.com/books?id=idmZIDcwCykC&pg=PA93}} Before 2000, more than 1.6 million tonnes of those alloys were used; at 1% manganese, this consumed 16,000 tonnes of manganese.

Manganese(IV) oxide was used in the original type of dry cell battery as an electron acceptor from zinc, and is the blackish material in carbon–zinc type flashlight cells. The manganese dioxide is reduced to the manganese oxide-hydroxide MnO(OH) during discharging, preventing the formation of hydrogen at the anode of the battery.

:MnO₂ + H₂O + e⁻ → MnO(OH) + {{chem|OH|-}}

The same material also functions in newer alkaline batteries (usually battery cells), which use the same basic reaction, but a different electrolyte mixture. In 2002, more than 230,000 tons of manganese dioxide was used for this purpose.{{cite journal|doi=10.1016/S0167-2738(00)00722-0|title=Batteries fifty years of materials development|date=2000|last=Dell|first=R. M.|journal=Solid State Ionics|volume=134|issue=1–2|pages=139–158}}

Copper alloys of manganese, such as Manganin, are commonly found in metal element shunt resistors used for measuring relatively large amounts of current. These alloys have very low temperature coefficient of resistance and are resistant to sulfur. This makes the alloys particularly useful in harsh automotive and industrial environments.{{cite web |title=WSK1216 |url=https://www.vishay.com/docs/30189/wsk1216.pdf |website=vishay |publisher=Vishay Intertechnology |access-date=30 April 2022}}

Manganese oxide and sulfate are components of fertilizers. In the year 2000, an estimated 20,000 tons of these compounds were used in fertilizers in the US alone. A comparable amount of Mn compounds was also used in animal feeds.{{cite book |doi=10.1002/14356007.a16_123 |chapter=Manganese Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2000 |last1=Reidies |first1=Arno H. |isbn=9783527303854 }}

Methylcyclopentadienyl manganese tricarbonyl is an additive in some unleaded gasoline to boost octane rating and reduce engine knocking.{{cite web |title=EPA Comments on the Gasoline Additive MMT |url=https://www.epa.gov/gasoline-standards/epa-comments-gasoline-additive-mmt |website=epa.gov |date=5 October 2015 |publisher=EPA |access-date=25 June 2023}}

Manganese(IV) oxide (manganese dioxide, MnO₂) is used as a reagent in organic chemistry for the oxidation of benzylic alcohols (where the hydroxyl group is adjacent to an aromatic ring).{{cite book |author1=Gérard Cahiez |author2=Mouâd Alami |author3=Richard J. K. Taylor |author4=Mark Reid |author5=Jonathan S. Foot |author6=Lee Fader |author7=Vikas Sikervar |author8=Jagadish Pabba |title=Encyclopedia of Reagents for Organic Synthesis |date=2017 |isbn=9780470842898 |chapter=Manganese Dioxide |doi = 10.1002/047084289X.rm021.pub4}} Manganese dioxide has been used since antiquity to oxidize and neutralize the greenish tinge in glass from trace amounts of iron contamination.{{cite journal |doi=10.1007/s11837-998-0024-0|title=Glassmaking in renaissance Italy: The innovation of venetian cristallo|date=1998|last=Mccray |first=W. Patrick|journal=JOM|volume=50|pages=14–19|issue=5|bibcode=1998JOM....50e..14M|s2cid=111314824}} MnO₂ is also used in the manufacture of oxygen and chlorine and in drying black paints. In some preparations, it is a brown pigment for paint and is a constituent of natural umber.{{cite book |title=Shorter Oxford English Dictionary |url=https://archive.org/details/shorteroxfordeng00will_0 |publisher=Oxford University Press |year=2002 |isbn=978-0-19-860457-0 |quote=A red brown earth containing iron and manganese oxides and darker than ochre and sienna, used to make various pigments. |edition=5th}}

Tetravalent manganese is used as an activator in red-emitting phosphors. While many compounds are known which show luminescence,{{cite journal|journal=RSC Advances |date=2016|volume=6|issue=89|pages=86285–86296|first=Daquin|last=Chen|author2=Zhou, Yang |author3=Zhong, Jiasong |title=A review on Mn⁴⁺ activators in solids for warm white light-emitting diodes|doi=10.1039/C6RA19584A|bibcode=2016RSCAd...686285C}} the majority are not used in commercial application due to low efficiency or deep red emission.{{cite journal|journal=Journal of Luminescence |date=2016|volume=177|pages=354–360|first=Florian|last=Baur|author2=Jüstel, Thomas|title=Dependence of the optical properties of Mn⁴⁺ activated A₂Ge₄O₉ (A=K,Rb) on temperature and chemical environment|doi=10.1016/j.jlumin.2016.04.046|bibcode=2016JLum..177..354B}}{{Cite journal|last1=Jansen|first1=T.|last2=Gorobez|first2=J.|last3=Kirm|first3=M.|last4=Brik|first4=M. G.|last5=Vielhauer|first5=S.|last6=Oja|first6=M.|last7=Khaidukov|first7=N. M.|last8=Makhov|first8=V. N.|last9=Jüstel|first9=T.|date=1 January 2018|title=Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺ Inverse Garnet for High Power Phosphor Converted LEDs|journal=ECS Journal of Solid State Science and Technology|volume=7|issue=1|pages=R3086–R3092|doi=10.1149/2.0121801jss|s2cid=103724310 |doi-access=free}} However, several Mn⁴⁺ activated fluorides were reported as potential red-emitting phosphors for warm-white LEDs.{{Cite journal|last1=Jansen|first1=Thomas|last2=Baur|first2=Florian|last3=Jüstel|first3=Thomas|title=Red emitting K₂NbF₇:Mn⁴⁺ and K₂TaF₇:Mn⁴⁺ for warm-white LED applications|journal=Journal of Luminescence|volume=192|pages=644–652|doi=10.1016/j.jlumin.2017.07.061|year=2017|bibcode=2017JLum..192..644J}}{{Cite journal|last1=Zhou|first1=Zhi|last2=Zhou|first2=Nan|last3=Xia|first3=Mao|last4=Yokoyama|first4=Meiso|last5=Hintzen|first5=H. T. (Bert)|date=6 October 2016|title=Research progress and application prospects of transition metal Mn⁴⁺-activated luminescent materials|journal=Journal of Materials Chemistry C|volume=4|issue=39|pages=9143–9161|doi=10.1039/c6tc02496c}} But to this day, only K₂SiF₆:Mn⁴⁺ is commercially available for use in warm-white LEDs.{{cite web|url=https://energy.gov/sites/prod/files/2015/02/f19/setlur_emitters_2015.pdf|title=TriGain LED phosphor system using red Mn⁴⁺-doped complex fluorides|publisher=GE Global Research |access-date=10 December 2022}}

File:1945-P-Jefferson-War-Nickel-Reverse.JPG

The metal is occasionally used in coins; until 2000, the only United States coin to use manganese was the "wartime" nickel from 1942 to 1945.{{cite journal|journal=Western Journal of Medicine |date=2001|volume=175|issue=2|pages=112–114|first=Raymond T.|last=Kuwahara|author2=Skinner III, Robert B. |author3=Skinner Jr., Robert B. |title=Nickel coinage in the United States|doi=10.1136/ewjm.175.2.112|pmid=11483555|pmc=1071501}} An alloy of 75% copper and 25% nickel was traditionally used for the production of nickel coins. However, because of shortage of nickel metal during the war, it was substituted by more available silver and manganese, thus resulting in an alloy of 56% copper, 35% silver and 9% manganese. Since 2000, dollar coins, for example the Sacagawea dollar and the Presidential $1 coins, are made from a brass containing 7% of manganese with a pure copper core.{{cite web|url=http://www.usmint.gov/mint_programs/golden_dollar_coin/index.cfm?action=sacDesign|title=Design of the Sacagawea dollar|publisher=United States Mint|access-date=4 May 2009|archive-date=22 April 2021|archive-url=https://web.archive.org/web/20210422194127/https://www.usmint.gov/learn/coin-and-medal-programs?action=sacdesign|url-status=dead}}

Manganese compounds have been used as pigments and for the coloring of ceramics and glass. The brown color of ceramic is sometimes the result of manganese compounds.{{cite book|title=Ceramics for the Archaeologist|first=Anna Osler|last=Shepard|publisher=Carnegie Institution of Washington|date=1956|pages=40–42|isbn=978-0-87279-620-1|chapter=Manganese and Iron–Manganese Paints}} In the glass industry, manganese compounds are used for two effects. Manganese(III) reacts with iron(II) to reduce strong green color in glass by forming less-colored iron(III) and slightly pink manganese(II), compensating for the residual color of the iron(III). Larger quantities of manganese are used to produce pink colored glass. In 2009, Mas Subramanian and associates at Oregon State University discovered that manganese can be combined with yttrium and indium to form an intensely blue, non-toxic, inert, fade-resistant pigment, YInMn Blue,{{Cite journal |last1=Li |first1=Jun |last2=Lorger |first2=Simon |last3=Stalick |first3=Judith K. |last4=Sleight |first4=Arthur W. |last5=Subramanian |first5=M. A. |date=2016-10-03 |title=From Serendipity to Rational Design: Tuning the Blue Trigonal Bipyramidal Mn 3+ Chromophore to Violet and Purple through Application of Chemical Pressure |url=https://pubs.acs.org/doi/10.1021/acs.inorgchem.6b01639 |journal=Inorganic Chemistry |language=en |volume=55 |issue=19 |pages=9798–9804 |doi=10.1021/acs.inorgchem.6b01639 |pmid=27622607 |issn=0020-1669}} the first new blue pigment discovered in 200 years.{{cite web |url=https://ideas.ted.com/how-on-earth-do-you-discover-a-brand-new-blue-pigment-by-accident/ |title=How on earth do you discover a brand-new blue pigment? By accident. |date=June 28, 2018 |first=Elian |last=Silverman |publisher=TED Ideas |access-date=June 26, 2024}}

File:Arginase.jpeg – the manganese atoms are shown in yellow.]]{{Main|Manganese in biology}}

Many classes of enzymes contain manganese cofactors including oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Other enzymes containing manganese are arginase and a Mn-containing superoxide dismutase (Mn-SOD). Some reverse transcriptases of many retroviruses (although not lentiviruses such as HIV) contain manganese. Manganese-containing polypeptides are the diphtheria toxin, lectins, and integrins.{{cite journal |doi=10.1021/acs.accounts.7b00343 |title=Manganese–Oxygen Intermediates in O–O Bond Activation and Hydrogen-Atom Transfer Reactions |year=2017 |last1=Rice |first1=Derek B. |last2=Massie |first2=Allyssa A. |last3=Jackson |first3=Timothy A. |journal=Accounts of Chemical Research |volume=50 |issue=11 |pages=2706–2717 |pmid=29064667 }}

The oxygen-evolving complex (OEC), containing four atoms of manganese, is a part of photosystem II contained in the thylakoid membranes of chloroplasts. The OEC is responsible for the terminal photooxidation of water during the light reactions of photosynthesis, i.e., it is the catalyst that makes the O₂ produced by plants.{{cite journal|last1=Umena|first1=Yasufumi|last2=Kawakami|first2=Keisuke|last3=Shen|first3=Jian-Ren|last4=Kamiya |first4=Nobuo|title=Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 Å|journal=Nature|volume=473|issue=7345|pages=55–60|doi=10.1038/nature09913|pmid=21499260|date=May 2011|bibcode=2011Natur.473...55U|s2cid=205224374|url=http://ousar.lib.okayama-u.ac.jp/files/public/4/47455/20160528084139320094/Nature_473_55–60.pdf}}{{cite encyclopedia|last=Dismukes|first=G. Charles|author2=Willigen, Rogier T. van|title=Manganese: The Oxygen-Evolving Complex & Models Based in part on the article Manganese: Oxygen-Evolving Complex & Models by Lars-Erik Andréasson & Tore Vänngård which appeared in the Encyclopedia of Inorganic Chemistry, First Edition, First Edition|date=2006|encyclopedia=Encyclopedia of Inorganic Chemistry|doi=10.1002/0470862106.ia128|chapter=Manganese: The Oxygen-Evolving Complex & Models|isbn=978-0470860786}}

Manganese is an essential human dietary element and is present as a coenzyme in several biological processes, which include macronutrient metabolism, bone formation, and free radical defense systems. Manganese is a critical component in dozens of proteins and enzymes.{{cite book

|last1=Erikson|first1=Keith M. |last2=Ascher |first2=Michael

|editor1-last=Sigel|editor1-first=Astrid

|editor2-last=Freisinger|editor2-first=Eva

|editor3-last=Sigel|editor3-first=Roland K. O.

|editor4-last=Carver|editor4-first=Peggy L.

|title=Essential Metals in Medicine:Therapeutic Use and Toxicity of Metal Ions in the Clinic

|series=Metal Ions in Life Sciences |volume=19 |date=2019 |publisher=de Gruyter GmbH|location=Berlin

|isbn=978-3-11-052691-2

|doi=10.1515/9783110527872-016

|pmid=30855111

|pages=253–266|chapter=Chapter 10. Manganese: Its Role in Disease and Health|s2cid=73725546 }}

The human body contains about 12 mg of manganese, mostly in the bones. The soft tissue remainder is concentrated in the liver and kidneys. In the human brain, the manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes.{{cite journal|doi=10.1016/S0165-0173(02)00234-5|title=Manganese action in brain function|date=2003 |last=Takeda |first=A.|journal=Brain Research Reviews|volume=41|issue=1|pmid=12505649|pages=79–87|s2cid=1922613}}

The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for minerals in 2001. For manganese, there was not sufficient information to set EARs and RDAs, so needs are described as estimates for Adequate Intakes (AIs). As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of manganese, the adult UL is set at 11 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).{{cite book|chapter=Manganese|chapter-url=https://www.nap.edu/read/10026/chapter/12 |title=Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Chromium, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Chromium|publisher= National Academy Press|year= 2001|pages=394–419|pmid=25057538|isbn=978-0-309-07279-3|author1=Institute of Medicine (US) Panel on Micronutrients }} Manganese deficiency is rare.See {{cite web|url=http://lpi.oregonstate.edu/mic/minerals/manganese |title=Manganese|work=Micronutrient Information Center|publisher=Oregon State University Linus Pauling Institute|date=23 April 2014}}

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 people ages 15 and older, the AI is set at 3.0 mg/day. AIs for pregnancy and lactation are 3.0 mg/day. For children ages 1–14 years, the AIs increase with age from 0.5 to 2.0 mg/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}} The EFSA reviewed the same safety question and decided that there was insufficient information to set a UL.{{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}}

For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For manganese labeling purposes, 100% of the Daily Value was 2.0 mg, but as of 27 May 2016 it was revised to 2.3 mg to bring it into agreement with the RDA.{{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.}}{{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.

Excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease.{{cite book |first1=Daiana|last1=Silva Avila|first2=Robson|last2=Luiz Puntel|first3=Michael|last3=Aschner|chapter=Manganese in Health and Disease |editor=Astrid Sigel|editor2=Helmut Sigel |editor3=Roland K. O. Sigel|title=Interrelations between Essential Metal Ions and Human Diseases|series=Metal Ions in Life Sciences

|volume=13|date=2013|publisher=Springer|pages=199–227|doi=10.1007/978-94-007-7500-8_7|pmid=24470093|pmc=6589086|isbn=978-94-007-7499-5}}

{{main|Manganese deficiency (medicine)|l1=Manganese deficiency}}

Manganese deficiency in humans, which is rare, results in a number of medical problems. A deficiency of manganese causes skeletal deformation in animals and inhibits the production of collagen in wound healing.{{cite journal |last1=Wang |first1=Cui-Yue |last2=Xia |first2=Wei-Hao |last3=Wang |first3=Lin |last4=Wang |first4=Zhen-Yong |title=Manganese deficiency induces avian tibial dyschondroplasia by inhibiting chondrocyte proliferation and differentiation |url=https://www.sciencedirect.com/science/article/abs/pii/S0034528821002691 |journal=Research in Veterinary Science |pages=164–170 |doi=10.1016/j.rvsc.2021.08.018 |date=1 November 2021|volume=140 |pmid=34481207 }}

Waterborne manganese has a greater bioavailability than dietary manganese. According to results from a 2010 study,{{cite journal|doi=10.1289/ehp.1002321 |volume=119|pages=138–143|pmid=20855239 |issue=1 |pmc=3018493|year=2011 |last1=Bouchard |first1=M. F |title=Intellectual impairment in school-age children exposed to manganese from drinking water |journal=Environmental Health Perspectives |last2=Sauvé |first2=S |last3=Barbeau |first3=B |last4=Legrand |first4=M |last5=Bouffard |first5=T |last6=Limoges |first6=E |last7=Bellinger |first7=D. C |last8=Mergler |first8=D |bibcode=2011EnvHP.119..138B }} higher levels of exposure to manganese in drinking water are associated with increased intellectual impairment and reduced intelligence quotients in school-age children. It is hypothesized that long-term exposure due to inhaling the naturally occurring manganese in shower water puts up to 8.7 million Americans at risk.{{cite journal|doi=10.1081/CLT-100102427|pmid=10382563|title=Manganese|date=1999 |author=Barceloux, Donald |journal=Clinical Toxicology|volume=37|last2=Barceloux|first2=Donald|issue=2|pages=293–307}} However, data indicates that the human body can recover from certain adverse effects of overexposure to manganese if the exposure is stopped and the body can clear the excess.{{cite journal|pmid=8143974 |year=1994 |last1=Devenyi |first1=A. G |title=Dystonia, hyperintense basal ganglia, and high whole blood manganese levels in Alagille's syndrome |journal=Gastroenterology |volume=106 |issue=4 |pages=1068–71 |last2=Barron |first2=T. F |last3=Mamourian |first3=A. C |doi=10.1016/0016-5085(94)90769-2|s2cid=2711273 }}

Mn levels can increase in seawater when hypoxic periods occur.{{Cite journal|last1=Hernroth|first1=Bodil|last2=Krång|first2=Anna-Sara|last3=Baden|first3=Susanne|date=February 2015|title=Bacteriostatic suppression in Norway lobster (Nephrops norvegicus) exposed to manganese or hypoxia under pressure of ocean acidification|url=http://dx.doi.org/10.1016/j.aquatox.2014.11.025|journal=Aquatic Toxicology|volume=159|pages=217–224|doi=10.1016/j.aquatox.2014.11.025|pmid=25553539|bibcode=2015AqTox.159..217H |issn=0166-445X}} Since 1990 there have been reports of Mn accumulation in marine organisms including fish, crustaceans, mollusks, and echinoderms. Specific tissues are targets in different species, including the gills, brain, blood, kidney, and liver/hepatopancreas. Physiological effects have been reported in these species. Mn can affect the renewal of immunocytes and their functionality, such as phagocytosis and activation of pro-phenoloxidase, suppressing the organisms' immune systems. This causes the organisms to be more susceptible to infections. As climate change occurs, pathogen distributions increase, and in order for organisms to survive and defend themselves against these pathogens, they need a healthy, strong immune system. If their systems are compromised from high Mn levels, they will not be able to fight off these pathogens and die.

File:Methylcyclopentadienyl manganese tricarbonyl.tif (MMT)]]

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an additive developed to replace lead compounds for gasolines to improve the octane rating. MMT is used only in a few countries. When exposed to the environment, fuels containing methylcyclopentadienyl manganese tricarbonyl degrade, releasing manganese into water and soils.{{cite journal |author1=Arthur W. Garrison |author2=N. Lee Wolfe |author3=Robert R. Swank Jr. |author4=Mark G. Cipollone |title=Environmental fate of methylcyclopentadienyl manganese tricarbonyl |journal=Environmental Toxicology and Chemistry |date=1995 |volume=14 |issue=11 |pages=1859–1864 |doi=10.1002/etc.5620141107 |bibcode=1995EnvTC..14.1859G |language=en}}

Manganese levels in the air decreased between 1953 and 1982, with higher levels in 1953.Agency for Toxic Substances and Disease Registry (2012) [http://www.atsdr.cdc.gov/toxprofiles/tp151-c6.pdf 6. Potential for human exposure], in [https://www.atsdr.cdc.gov/toxprofiledocs/index.html?id=102&tid=23 Toxicological Profile for Manganese], Atlanta, GA: U.S. Department of Health and Human Services. In general, breathing air with more than 5 micrograms of manganese per cubic meter can cause symptoms of manganese exposure. In lab-grown human kidney cells, higher levels of a protein called ferroportin are linked to lower manganese levels inside the cells and reduced cell damage, shown by better glutamate uptake and less leakage of a damage marker known as lactate dehydrogenase.{{cite journal|pmid=20002294|last1=Yin|first1=Z.|date=2010|pages=1190–8|issue=5|volume=112|last2=Jiang|first2=H.|journal=Journal of Neurochemistry|last3=Lee|first3=E. S.|last4=Ni|first4=M.|last5=Erikson|first5=K. M.|last6=Milatovic|first6=D.|last7=Bowman|first7=A. B.|last8=Aschner|first8=M.|title=Ferroportin is a manganese-responsive protein that decreases manganese cytotoxicity and accumulation |url=http://libres.uncg.edu/ir/uncg/f/K_Erickson_Ferroportin_2009.pdf|pmc=2819584|doi=10.1111/j.1471-4159.2009.06534.x}}

Manganese exposure in United States is regulated by the Occupational Safety and Health Administration (OSHA).{{cite web|title=Safety and Health Topics: Manganese Compounds (as Mn)|url=https://web.archive.org/web/20170801002948/https://www.osha.gov/dts/chemicalsampling/data/CH_250190.html|publisher=U.S. Occupational Safety and Health Administration}} People can be exposed to manganese in the workplace by breathing it in or swallowing it. OSHA has set the legal limit (permissible exposure limit) for manganese exposure in the workplace as 5 mg/m³ over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1 mg/m³ over an 8-hour workday and a short term limit of 3 mg/m³. At levels of 500 mg/m³, manganese is immediately dangerous to life and health.{{cite web|title=NIOSH Pocket Guide to Chemical Hazards – Manganese compounds and fume (as Mn)|url=https://www.cdc.gov/niosh/npg/npgd0379.html|publisher=Centers for Disease Control|access-date=19 November 2015}} In other countries, such as Germany, a general ceiling value for airborne manganese has been set to 0.5 mg/m³ ({{interlanguage link|Maximale Arbeitsplatz-Konzentration|de}}) and the maximium level of manganese in the body has been set to 20 mg/L.

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Manganese is essential for human health, albeit in milligram amounts. The current maximum safe concentration under U.S. EPA rules is 50 μg Mn/L.{{cite web|title=Drinking Water Contaminants|url=http://water.epa.gov/drink/contaminants/index.cfm|publisher=US EPA|access-date=2 February 2015}}

Manganese overexposure is most frequently associated with manganism, a rare neurological disorder associated with excessive manganese ingestion or inhalation. Historically, persons employed in the production or processing of manganese alloys{{cite book |author1=Brent Furbee |title=Clinical Neurotoxicology |date=2009 |publisher=Elsevier |isbn=9780323052603 |pages=293-301 |url=https://www.sciencedirect.com/science/article/abs/pii/B9780323052603500320 |access-date=5 May 2025 |chapter=Manganese}}Baselt, R. (2008) Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, pp. 883–886, {{ISBN|0-9626523-7-7}}.{{cite journal|doi=10.1023/A:1021970120965|date=2002|author=Normandin, Louise|journal=Metabolic Brain Disease |volume=17|pages=375–87|pmid=12602514|last2=Hazell|first2=A. S.|title=Manganese neurotoxicity: an update of pathophysiologic mechanisms |issue=4|s2cid=23679769}} have been at risk for developing manganism; however, health and safety regulations protect workers in developed nations. The disorder was first described in 1837 by British academic John Couper, who studied two patients who were manganese grinders.{{cite journal|last=Couper|first=John|title=On the effects of black oxide of manganese when inhaled into the lungs|journal=Br. Ann. Med. Pharm. Vital Stat. Gen. Sci.|date=1837|volume=1 |pages=41–42}}

Manganism is a biphasic disorder. In its early stages, an intoxicated person may experience depression, mood swings, compulsive behaviors, and psychosis. Early neurological symptoms give way to late-stage manganism, which resembles Parkinson's disease. Symptoms include weakness, monotone and slowed speech, an expressionless face, tremor, forward-leaning gait, inability to walk backwards without falling, rigidity, and general problems with dexterity, gait and balance.{{cite journal|last=Cersosimo|first=M. G.|author2=Koller, W.C.|title=The diagnosis of manganese-induced parkinsonism |journal=NeuroToxicology|date=2007|volume=27|pages=340–346|doi=10.1016/j.neuro.2005.10.006|pmid=16325915|issue=3}} Unlike Parkinson's disease, manganism is not associated with loss of the sense of smell and patients are typically unresponsive to treatment with L-DOPA.{{cite journal|last=Lu|first=C. S.|author2=Huang, C.C |author3=Chu, N.S. |author4=Calne, D.B. |title=Levodopa failure in chronic manganism|journal=Neurology|date=1994|volume=44|pages=1600–1602|doi=10.1212/WNL.44.9.1600|pmid=7936281|issue=9|s2cid=38040913}} Symptoms of late-stage manganism become more severe over time even if the source of exposure is removed and brain manganese levels return to normal.

Chronic manganese exposure has been shown to produce a parkinsonism-like illness characterized by movement abnormalities.{{cite journal | vauthors = Guilarte TR, Gonzales KK | title = Manganese-Induced Parkinsonism Is Not Idiopathic Parkinson's Disease: Environmental and Genetic Evidence | journal = Toxicological Sciences| volume = 146 | issue = 2 | pages = 204–12 | date = August 2015 | pmid = 26220508 | pmc = 4607750 | doi = 10.1093/toxsci/kfv099 | type= Review}} This condition is not responsive to typical therapies used in the treatment of PD, suggesting an alternative pathway to the typical dopaminergic loss within the substantia nigra. Manganese may accumulate in the basal ganglia, leading to the abnormal movements.{{cite journal | vauthors = Kwakye GF, Paoliello MM, Mukhopadhyay S, Bowman AB, Aschner M | title = Manganese-Induced Parkinsonism and Parkinson's Disease: Shared and Distinguishable Features | journal = Int J Environ Res Public Health | volume = 12 | issue = 7 | pages = 7519–40 | date = July 2015 | pmid = 26154659 | pmc = 4515672 | doi = 10.3390/ijerph120707519 | type= Review | doi-access = free }} A mutation of the SLC30A10 gene, a manganese efflux transporter necessary for decreasing intracellular Mn, has been linked with the development of this Parkinsonism-like disease.{{cite journal | vauthors = Peres TV, Schettinger MR, Chen P, Carvalho F, Avila DS, Bowman AB, Aschner M | title = Manganese-induced neurotoxicity: a review of its behavioral consequences and neuroprotective strategies | journal = BMC Pharmacology & Toxicology| volume = 17 | issue = 1 | pages = 57 | date = November 2016 | pmid = 27814772 | pmc = 5097420 | doi = 10.1186/s40360-016-0099-0 | type= Review | doi-access = free }} The Lewy bodies typical to PD are not seen in Mn-induced parkinsonism.

Animal experiments have given the opportunity to examine the consequences of manganese overexposure under controlled conditions. In (non-aggressive) rats, manganese induces mouse-killing behavior.{{cite journal|last1=Lazrishvili|display-authors=etal|first1=I.|title=Manganese loading induces mouse-killing behaviour in nonaggressive rats|journal= Journal of Biological Physics and Chemistry|date=2016|volume=16|issue=3|pages=137–141 |doi=10.4024/31LA14L.jbpc.16.03}}

Manganese compounds are less toxic than those of other widespread metals, such as nickel and copper.{{cite book|pages=31 |title=Manganese|first=Heather|last=Hasan|publisher=The Rosen Publishing Group|date=2008|isbn=978-1-4042-1408-8 |url=https://books.google.com/books?id=nRmpEaudmTYC&pg=PA31}} However, exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m³ even for short periods because of its toxicity level.{{cite web|url=http://www.environmentwriter.org/resources/backissues/chemicals/manganese.htm |archive-url=https://web.archive.org/web/20060828211701/http://www.environmentwriter.org/resources/backissues/chemicals/manganese.htm |url-status=dead |archive-date=28 August 2006 |title=Manganese Chemical Background |access-date=30 April 2008 |publisher=Metcalf Institute for Marine and Environmental Reporting University of Rhode Island |date=April 2006 }} Manganese poisoning has been linked to impaired motor skills and cognitive disorders.{{cite web|url=http://rais.ornl.gov/tox/profiles/mn.html|publisher=Oak Ridge National Laboratory|title=Risk Assessment Information System Toxicity Summary for Manganese|access-date=23 April 2008}}

A protein called DMT1 is the major transporter in manganese absorption from the intestine and may be the major transporter of manganese across the blood–brain barrier. DMT1 also transports inhaled manganese across the nasal epithelium. The proposed mechanism for manganese toxicity is that dysregulation leads to oxidative stress, mitochondrial dysfunction, glutamate-mediated excitotoxicity, and aggregation of proteins.{{Cite journal|last1=Prabhakaran|first1=K.|last2=Ghosh|first2=D.|last3=Chapman|first3=G.D.|last4=Gunasekar|first4=P.G.|date=2008|title=Molecular mechanism of manganese exposure-induced dopaminergic toxicity|journal=Brain Research Bulletin|volume=76|issue=4|pages=361–367|doi=10.1016/j.brainresbull.2008.03.004|pmid=18502311|s2cid=206339744|issn=0361-9230}}

• Manganese exporter, membrane transport protein
• List of countries by manganese production
• Parkerizing

{{Reflist|30em}}

{{sfn whitelist|CITEREFGreenwoodEarnshaw1997}}

• {{Greenwood&Earnshaw2nd}}

{{Sister project links|wikt=manganese|n=no|q=no|s=no}}

• [http://www.npi.gov.au/substances/manganese/index.html National Pollutant Inventory – Manganese and compounds Fact Sheet]
• [http://www.manganese.org International Manganese Institute]
• [https://www.cdc.gov/niosh/topics/manganese/ NIOSH Manganese Topic Page]
• [http://www.periodicvideos.com/videos/025.htm Manganese] at The Periodic Table of Videos (University of Nottingham)
• [https://www.manganese-dendrite.com All about Manganese Dendrites]
• [https://www.epa.gov/smm/electric-arc-furnace-eaf-slag Electric Arc Furnace (EAF) Slag]

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