View source for Chemistry:Magnetite

{{short description|Iron ore mineral}}
{{Infobox mineral
| name          = Magnetite
| category      = {{ubl| [[Chemistry:Oxide minerals|Oxide minerals]] | [[Chemistry:Spinel group|Spinel group]] | Spinel structural group }}
| boxwidth      = 
| image         = Magnetite-118736.jpg
| alt           = 
| caption       = Magnetite from Bolivia
| formula       = iron(II,III) oxide, {{chem2|Fe(2+)Fe2(3+)O4}}
| IMAsymbol     = Mag<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>
| molweight     = 
| strunz        = 4.BB.05
| system        = Isometric
| class         = Hexoctahedral (m{{overline|3}}m) <br/>[[Chemistry:H-M symbol|H-M symbol]]: (4/m {{overline|3}} 2/m)
| symmetry      = ''Fd{{overline|3}}m'' (no. 227)
| unit cell     = a = 8.397&nbsp;Å; Z&nbsp;=&nbsp;8
| color         = Black, gray with brownish tint in reflected sun
| habit         = Octahedral, fine granular to massive
| twinning      = On {Ill} as both twin and composition plane, the spinel law, as contact twins
| cleavage      = Indistinct, parting on {Ill}, very good
| fracture      = Uneven
| tenacity      = Brittle
| mohs          = 5.5–6.5
| luster        = Metallic
| refractive    = 
| opticalprop   = 
| birefringence = 
| pleochroism   = 
| streak        = Black
| gravity       = 5.17–5.18
| density       = 
| melt          = 
| fusibility    = 
| diagnostic    = 
| solubility    = Dissolves slowly in [[Chemistry:Hydrochloric acid|hydrochloric acid]]
| diaphaneity   = Opaque
| other         = 
| var1          = [[Physics:Lodestone|Lodestone]]
| var1text      = Magnetic with definite north and south poles
| references    = <ref name=Handbook>{{cite book |chapter=Magnetite |last1=Anthony |first1=John W. |last2=Bideaux |first2=Richard A. |last3=Bladh |first3=Kenneth W. |title=Handbook of Mineralogy |publisher=Mineralogical Society of America |location=Chantilly, VA |pages=333|chapter-url=http://www.handbookofmineralogy.org/pdfs/magnetite.pdf|access-date=15 November 2018}}</ref><ref name=Mindat>{{cite web |title=Magnetite |url=http://www.mindat.org/min-2538.html |publisher=mindat.org and the Hudson Institute of Mineralogy |access-date=15 November 2018}}</ref><ref name=Webmin>{{cite web |last1=Barthelmy |first1=Dave |title=Magnetite Mineral Data |url=http://webmineral.com/data/Magnetite.shtml |website=Mineralogy Database |publisher=webmineral.com |access-date=15 November 2018}}</ref><ref>{{cite book|last1 = Hurlbut|first1 = Cornelius S.|last2= Klein |first2=Cornelis |title = Manual of Mineralogy|edition = 20th|publisher = Wiley|year = 1985|isbn = 978-0-471-80580-9|url = https://archive.org/details/manualofmineralo00klei}}</ref>
}}

[[File:Magnetite sample with neodymium magnet.jpg|thumb|upright=1.2|Magnetite is one of the very few minerals that is ferrimagnetic; it is attracted by a magnet as shown here]] 
[[File:Kristallstruktur Magnetit.png|thumb|Unit cell of magnetite. The gray spheres are oxygen, green are divalent iron, blue are trivalent iron. Also shown are an iron atom in an octahedral space (light blue) and another in a tetrahedral space (gray).]]
'''Magnetite''' is a [[Earth:Mineral|mineral]] and one of the main [[Earth:Iron ore|iron ore]]s, with the chemical formula {{chem2|Fe(2+)Fe2(3+)O4}}. It is one of the [[Chemistry:Iron oxide|oxides of iron]], and is [[Physics:Ferrimagnetism|ferrimagnetic]];<ref name="Ferrimag2005">{{Cite book | author1-first=S.D. | author1-last=Jacobsen |author2-first=H.J. | author2-last=Reichmann | author3-first=A.  | author3-last=Kantor | author4-first=H.A. | author4-last=Spetzler | chapter=A gigahertz ultrasonic interferometer for the diamond anvil cell and high-pressure elasticity of some iron-oxide minerals | editor1-last=Chen | editor1-first=J. | editor2-last=Duffy | editor2-first=T.S. | editor3-last=Dobrzhinetskaya | editor3-first=L.F. | editor4-last=Wang | editor4-first=Y. | editor5-last=Shen | editor5-first=G. | title=Advances in High-Pressure Technology for Geophysical Applications | pages=25–48  | publisher=Elsevier Science | date=2005 | isbn=978-0-444-51979-5 | doi=10.1016/B978-044451979-5.50004-1}}</ref> it is attracted to a [[Physics:Magnet|magnet]] and can be [[Physics:Magnetization|magnetized]] to become a permanent magnet itself.<ref name="Dana">{{cite book 
  | last = Hurlbut 
  | first = Cornelius Searle 
  | author2 = W. Edwin Sharp 
  | author3 = Edward Salisbury Dana 
  | title = Dana's minerals and how to study them 
  | publisher = John Wiley and Sons 
  | year = 1998 
  | pages = [https://archive.org/details/danasmineralshow00hurl/page/96 96] 
  | url = https://archive.org/details/danasmineralshow00hurl/page/96 
  | isbn = 978-0-471-15677-2 
  }}</ref><ref name="Wasilewski">{{cite journal
 |doi=10.1029/1999GL900496
 |first=Peter
 |last=Wasilewski
 |author2=Günther Kletetschka
 |title=Lodestone: Nature's only permanent magnet - What it is and how it gets charged
 |journal=[[Earth:Geophysical Research Letters|Geophysical Research Letters]]
 |volume=26
 |issue=15
 |pages=2275–78
 |year=1999
 |bibcode = 1999GeoRL..26.2275W
 |s2cid=128699936
 }}</ref> With the exception of extremely rare native iron deposits, it is the most magnetic of all the naturally occurring minerals on Earth.<ref name="Dana" /><ref>{{cite journal|doi=10.1073/pnas.262514499|title=Direct imaging of nanoscale magnetic interactions in minerals|year=2002|last1=Harrison|first1=R. J.|journal=Proceedings of the National Academy of Sciences|volume=99|pages=16556–16561|pmid=12482930|last2=Dunin-Borkowski|first2=RE|last3=Putnis|first3=A|issue=26|pmc=139182|bibcode = 2002PNAS...9916556H |doi-access=free}}</ref>  Naturally magnetized pieces of magnetite, called [[Physics:Lodestone|lodestone]], will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism.<ref name="Tremolet">{{cite book | last = Du Trémolet de Lacheisserie | first = Étienne |author2=Damien Gignoux |author3=Michel Schlenker  | title = Magnetism: Fundamentals | publisher = Springer | year = 2005 | pages = 3–6 | url = https://books.google.com/books?id=MgCExarQD08C&pg=PA3 | isbn = 0-387-22967-1}}</ref>

Magnetite is black or brownish-black with a metallic luster, has a [[Physics:Mohs scale of mineral hardness|Mohs hardness]] of 5–6 and leaves a black [[Earth:Streak (mineralogy)|streak]].<ref name="Dana" /> Small grains of magnetite are very common in igneous and metamorphic rocks.<ref>{{cite book |last1=Nesse |first1=William D. |title=Introduction to mineralogy |date=2000 |publisher=Oxford University Press |location=New York |isbn=9780195106916 |page=361}}</ref>

The chemical IUPAC name is [[Chemistry:Iron(II,III) oxide|iron(II,III) oxide]] and the common chemical name is ''ferrous-ferric oxide''.<ref>{{cite journal |last1=Morel |first1=Mauricio |last2=Martínez |first2=Francisco |last3=Mosquera |first3=Edgar |title=Synthesis and characterization of magnetite nanoparticles from mineral magnetite |journal=Journal of Magnetism and Magnetic Materials |date=October 2013 |volume=343 |pages=76–81 |doi=10.1016/j.jmmm.2013.04.075|bibcode=2013JMMM..343...76M }}</ref>

==Properties==
In addition to igneous rocks, magnetite also occurs in sedimentary rocks, including [[Earth:Banded iron formation|banded iron formation]]s and in lake and marine sediments as both detrital grains and as magnetofossils. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to [[Chemistry:Maghemite|maghemite]].<ref>{{cite journal | last1 = Maher | first1 = B. A. | last2 = Taylor | first2 = R. M. | year = 1988 | title = Formation of ultrafine-grained magnetite in soils | journal = Nature | volume = 336| issue = 6197 | pages = 368–370 | doi = 10.1038/336368a0 | bibcode = 1988Natur.336..368M | s2cid = 4338921 }}</ref>

=== Crystal structure ===
The chemical composition of magnetite is Fe<sup>2+</sup>(Fe<sup>3+</sup>)<sub>2</sub>(O<sup>2-</sup>)<sub>4</sub>. This indicates that magnetite contains both [[Chemistry:Ferrous|ferrous]] (divalent) and [[Chemistry:Ferric|ferric]] (trivalent) iron, suggesting crystallization in an environment containing intermediate levels of oxygen.<ref>{{Cite book |title=Mineral resources, economics and the environment |last1=Kesler |first1=Stephen E. |last2=Simon |first2=Adam F. |year=2015 |isbn=9781107074910 |edition=2nd |location=Cambridge, United Kingdom |publisher=Cambridge University Press |oclc=907621860}}</ref><ref name=Schwertmann /> The main details of its structure were established in 1915. It was one of the first crystal structures to be obtained using X-ray diffraction. The structure is inverse [[Chemistry:Spinel group|spinel]], with O<sup>2-</sup> ions forming a face-centered cubic lattice and iron cations occupying [[Physics:Interstitial site|interstitial site]]s. Half of the Fe<sup>3+</sup> cations occupy tetrahedral sites while the other half, along with Fe<sup>2+</sup> cations, occupy octahedral sites. The unit cell consists of thirty-two{{nbsp}}O<sup>2-</sup> ions and unit cell length is ''a'' = 0.839&nbsp;nm.<ref name=Schwertmann>{{Cite book|title=The Iron Oxides|last1=Cornell|last2=Schwertmann|publisher=VCH|year=1996|isbn=978-3-527-28576-1|location=New York|pages=28–30}}</ref><ref>[https://log-web.de/chemie/Start.htm?name=magnetite&lang=en an  alternative visualisation of the crystal structure of Magnetite using JSMol is found here].</ref>

As a member of the inverse spinel group, magnetite can form [[Physics:Solid solution|solid solution]]s with similarly structured minerals, including ulvospinel  ({{chem2|Fe2TiO4}}) and [[Chemistry:Magnesioferrite|magnesioferrite]] ({{chem2|MgFe2O4}}).{{sfn|Nesse|2000|p=360}}

Titanomagnetite, also known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many [[Earth:Mafic|mafic]] igneous rocks. Titanomagnetite may undergo oxy-exsolution during cooling, resulting in ingrowths of magnetite and ilmenite.{{sfn|Nesse|2000|p=360}}

=== Crystal morphology and size ===
Natural and synthetic magnetite occurs most commonly as [[Octahedron|octahedral]] crystals bounded by {111} planes and as [[Rhombic dodecahedron|rhombic-dodecahedra]].<ref name=Schwertmann /> Twinning occurs on the {111} plane.<ref name=Mindat/>

Hydrothermal synthesis usually produces single octahedral crystals which can be as large as {{cvt|10|mm||}} across.<ref name=Schwertmann /> In the presence of mineralizers such as 0.1{{nbsp}}M HI or 2{{nbsp}}M [[Chemistry:Ammonium chloride|NH<sub>4</sub>Cl]] and at 0.207{{nbsp}}[[Pascal (unit)|MPa]] at 416–800&nbsp;°C, magnetite grew as crystals whose shapes were a combination of rhombic-dodechahedra forms.<ref name=Schwertmann /> The crystals were more rounded than usual. The appearance of higher forms was considered as a result from a decrease in the surface energies caused by the lower surface to volume ratio in the rounded crystals.<ref name=Schwertmann />

=== Reactions ===
Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce [[Chemistry:Hematite|hematite]], and the mineral pair forms a [[Chemistry:Mineral redox buffer|buffer]] that can control how oxidizing its environment is (the [[Chemistry:Oxygen|oxygen]] [[Physics:Fugacity|fugacity]]). This buffer is known as the hematite-magnetite or HM buffer. At lower oxygen levels, magnetite can form a buffer with [[Chemistry:Quartz|quartz]] and [[Chemistry:Fayalite|fayalite]] known as the QFM buffer. At still lower oxygen levels, magnetite forms a buffer with [[Chemistry:Wüstite|wüstite]] known as the MW buffer. The QFM and MW buffers have been used extensively in laboratory experiments on rock chemistry. The QFM buffer, in particular, produces an oxygen fugacity close to that of most igneous rocks.<ref>{{cite journal |last1=Carmichael |first1=Ian S.E. |last2=Ghiorso |first2=Mark S. |title=Oxidation-reduction relations in basic magma: a case for homogeneous equilibria |journal=Earth and Planetary Science Letters |date=June 1986 |volume=78 |issue=2–3 |pages=200–210 |doi=10.1016/0012-821X(86)90061-0|bibcode=1986E&PSL..78..200C }}</ref><ref>{{cite book |last1=Philpotts |first1=Anthony R. |last2=Ague |first2=Jay J. |title=Principles of igneous and metamorphic petrology |date=2009 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=9780521880060 |edition=2nd |pages=261–265}}</ref>

Commonly, [[Earth:Igneous rock|igneous rock]]s contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite. Compositions of the mineral pairs are used to calculate oxygen fugacity: a range of [[Chemistry:Mineral redox buffer|oxidizing conditions]] are found in magmas and the oxidation state helps to determine how the magmas might evolve by fractional crystallization.<ref>{{cite book |last1=McBirney |first1=Alexander R. |title=Igneous petrology |date=1984 |publisher=Freeman, Cooper |location=San Francisco, Calif. |isbn=0198578105 |pages=125–127}}</ref> Magnetite also is produced from peridotites and [[Earth:Dunite|dunite]]s by [[Earth:Serpentinite|serpentinization]].<ref>{{cite book |last1=Yardley |first1=B. W. D. |title=An introduction to metamorphic petrology |date=1989 |publisher=Longman Scientific & Technical |location=Harlow, Essex, England |isbn=0582300967 |page=42}}</ref>

=== Magnetic properties ===
Lodestones were used as an early form of magnetic compass. Magnetite has been a critical tool in [[Earth:Paleomagnetism|paleomagnetism]], a science important in understanding [[Earth:Plate tectonics|plate tectonics]] and as historic data for [[Physics:Magnetohydrodynamics|magnetohydrodynamics]] and other scientific fields.{{sfn|Nesse|2000|p=361}}

The relationships between magnetite and other iron oxide minerals such as [[Chemistry:Ilmenite|ilmenite]], hematite, and [[Chemistry:Ulvöspinel|ulvospinel]] have been much studied; the [[Earth:Metamorphic reaction|reaction]]s between these minerals and oxygen influence how and when magnetite preserves a record of the [[Earth:Earth's magnetic field|Earth's magnetic field]].<ref>{{cite book |last1=Tauxe |first1=Lisa |title=Essentials of paleomagnetism |date=2010 |publisher=University of California Press |location=Berkeley |isbn=9780520260313}}</ref>

At low temperatures, magnetite undergoes a crystal structure phase transition from a monoclinic structure to a cubic structure known as the [[Physics:Verwey transition|Verwey transition]]. Optical studies show that this metal to insulator transition is sharp and occurs around 120{{nbsp}}K.<ref>{{cite journal |author=Gasparov, L. V. |display-authors=0 |title=Infrared and Raman studies of the Verwey transition in magnetite |journal=Physical Review B |volume=62 |issue=12 |year=2000 |page=7939 |doi=10.1103/PhysRevB.62.7939|arxiv=cond-mat/9905278 |bibcode=2000PhRvB..62.7939G |citeseerx=10.1.1.242.6889 |s2cid=39065289 }}</ref> The Verwey transition is dependent on grain size, domain state, pressure,<ref>{{cite journal |author=Gasparov, L. V. |display-authors=0 |title=Magnetite: Raman study of the high-pressure and low-temperature effects |journal=Journal of Applied Physics |volume=97 |issue=10 |pages=10A922 |year=2005 |id=10A922|bibcode=2005JAP....97jA922G |arxiv=0907.2456 |doi=10.1063/1.1854476 |s2cid=55568498 }}</ref> and the iron-oxygen [[Chemistry:Stoichiometry|stoichiometry]].<ref>{{cite journal | year = 1985 | title = Influence of nonstoichiometry on the Verwey transition | journal = Phys. Rev. B | volume = 31 | issue = 1| pages = 430–436 | doi = 10.1103/PhysRevB.31.430  | pmid = 9935445 | last1 = Aragón | first1 = Ricardo| bibcode = 1985PhRvB..31..430A}}</ref> An isotropic point also occurs near the Verwey transition around 130{{nbsp}}K, at which point the sign of the magnetocrystalline anisotropy constant changes from positive to negative.<ref>{{cite book |editor1=Gubbins, D. |editor2=Herrero-Bervera, E. |year=2007 |title=Encyclopedia of geomagnetism and paleomagnetism |publisher=Springer Science & Business Media}}</ref> The [[Physics:Curie temperature|Curie temperature]] of magnetite is {{convert|580|C|K °F}}.<ref>{{cite journal |last1=Fabian |first1=K. |last2=Shcherbakov |first2=V. P. |last3=McEnroe |first3=S. A. |title=Measuring the Curie temperature |journal=Geochemistry, Geophysics, Geosystems |date=April 2013 |volume=14 |issue=4 |pages=947–961 |doi=10.1029/2012GC004440|bibcode=2013GGG....14..947F |doi-access=free |hdl=11250/2491932 |hdl-access=free }}</ref>

If magnetite is in a large enough quantity it can be found in [[Physics:Aeromagnetic survey|aeromagnetic survey]]s using a [[Physics:Magnetometer|magnetometer]] which measures magnetic intensities.<ref>{{Cite web |url=http://www.australianminesatlas.gov.au/education/down_under/exploration/magsurv.html |title=Magnetic Surveys |website=Minerals Downunder |publisher=Australian Mines Atlas |access-date=2018-03-23|date=2014-05-15 }}</ref>

=== Melting point ===
Solid magnetite particles melt at about {{Convert|1583–1597|C|F}}.<ref>{{Cite web |title=Magnetite |url=https://www.acs.org/content/acs/en/molecule-of-the-week/archive/m/magnetite.html |access-date=2022-07-06 |website=American Chemical Society |language=en}}</ref><ref>{{Cite book |url=https://www.worldcat.org/oclc/326982496 |title=CRC handbook of metal etchants |date=1991 |publisher=CRC Press |author1=Perrin Walker |author2=William H. Tarn |isbn=0-8493-3623-6 |location=Boca Raton |oclc=326982496}}</ref>{{Rp|page=794}}

==Distribution of deposits==
[[File:HeavyMineralsBeachSand.jpg|thumb|Magnetite and other heavy minerals (dark) in a quartz [[Earth:Beach|beach]] sand (Chennai, {{wipe|India}}).]]
Magnetite is sometimes found in large quantities in beach sand. Such [[Earth:Black sand|black sand]]s (mineral sands or iron sands) are found in various places, such as Lung Kwu Tan in Hong Kong; {{wipe|California}}, United States; and the west coast of the North Island of New Zealand.<ref>{{cite encyclopedia
 |url= http://www.teara.govt.nz/en/iron-and-steel/1 |title=1. Iron – an abundant resource - Iron and steel |first= Fleur |last=Templeton  |encyclopedia=Te Ara Encyclopedia of New Zealand |access-date=4 January 2013 }}</ref> The magnetite, eroded from rocks, is carried to the beach by rivers and concentrated by wave action and currents. Huge deposits have been found in banded iron formations.<ref>{{cite journal |last1=Rasmussen |first1=Birger |last2=Muhling |first2=Janet R. |title=Making magnetite late again: Evidence for widespread magnetite growth by thermal decomposition of siderite in Hamersley banded iron formations |journal=Precambrian Research |date=March 2018 |volume=306 |pages=64–93 |doi=10.1016/j.precamres.2017.12.017|bibcode=2018PreR..306...64R }}</ref><ref>{{cite journal |last1=Keyser |first1=William |last2=Ciobanu |first2=Cristiana L. |last3=Cook |first3=Nigel J. |last4=Wade |first4=Benjamin P. |last5=Kennedy |first5=Allen |last6=Kontonikas-Charos |first6=Alkiviadis |last7=Ehrig |first7=Kathy |last8=Feltus |first8=Holly |last9=Johnson |first9=Geoff |title=Episodic mafic magmatism in the Eyre Peninsula: Defining syn- and post-depositional BIF environments for iron deposits in the Middleback Ranges, South Australia |journal=Precambrian Research |date=February 2020 |volume=337 |pages=105535 |doi=10.1016/j.precamres.2019.105535|bibcode=2020PreR..33705535K |s2cid=210264705 }}</ref> These sedimentary rocks have been used to infer changes in the oxygen content of the atmosphere of the Earth.<ref name=Klein>{{cite journal|last1=Klein|first1=C.|title=Some Precambrian banded iron-formations (BIFs) from around the world: Their age, geologic setting, mineralogy, metamorphism, geochemistry, and origins|journal=American Mineralogist|date=1 October 2005|volume=90|issue=10|pages=1473–1499|doi=10.2138/am.2005.1871|bibcode=2005AmMin..90.1473K|s2cid=201124189 }}</ref>

<!-- Magnetite is a very common mineral and an exhaustive list of occurrences is not feasible. Please restrict this list to the most notable occurrences as established by reliable sources. -->
Large deposits of magnetite are also found in the Atacama region of Chile ([[Earth:Chilean Iron Belt|Chilean Iron Belt]]);<ref>{{cite journal |last1=Ménard |first1=J. -J. |title=Relationship between altered pyroxene diorite and the magnetite mineralization in the Chilean Iron Belt, with emphasis on the El Algarrobo iron deposits (Atacama region, Chile) |journal=Mineralium Deposita |date=June 1995 |volume=30 |issue=3–4 |pages=268–274 |doi=10.1007/BF00196362|bibcode=1995MinDe..30..268M |s2cid=130095912 }}</ref> the Valentines region of Uruguay;<ref>{{cite journal |last1=Wallace |first1=Roberts M. |title=Geological reconnaissance of some Uruguayan iron and manganese deposits in 1962 |journal=U.S. Geological Survey Open File Report |series=Open-File Report |date=1976 |volume=76-466 |doi=10.3133/ofr76466 |url=https://pubs.usgs.gov/of/1976/0466/report.pdf |access-date=15 February 2021}}</ref> Kiruna, Sweden;<ref>{{cite journal |last1=Knipping |first1=Jaayke L. |last2=Bilenker |first2=Laura D. |last3=Simon |first3=Adam C. |last4=Reich |first4=Martin |last5=Barra |first5=Fernando |last6=Deditius |first6=Artur P. |last7=Lundstrom |first7=Craig |last8=Bindeman |first8=Ilya |last9=Munizaga |first9=Rodrigo |title=Giant Kiruna-type deposits form by efficient flotation of magmatic magnetite suspensions |journal=Geology |date=July 2015 |volume=43 |issue=7 |pages=591–594 |doi=10.1130/G36650.1|bibcode=2015Geo....43..591K |hdl=10533/228146 |hdl-access=free }}</ref> the Tallawang region of New South Wales;<ref>{{cite journal |last1=Clark |first1=David A. |title=Interpretation of the magnetic gradient tensor and normalized source strength applied to the Tallawang magnetite skarn deposit, New South Wales, Australia |journal=SEG Technical Program Expanded Abstracts 2012 |date=September 2012 |pages=1–5 |doi=10.1190/segam2012-0700.1}}</ref> and in the Adirondack Mountains of New York in the United States.<ref>{{cite journal |last1=Valley |first1=Peter M. |last2=Hanchar |first2=John M. |last3=Whitehouse |first3=Martin J. |title=New insights on the evolution of the Lyon Mountain Granite and associated Kiruna-type magnetite-apatite deposits, Adirondack Mountains, New York State |journal=Geosphere |date=April 2011 |volume=7 |issue=2 |pages=357–389 |doi=10.1130/GES00624.1|bibcode=2011Geosp...7..357V |doi-access=free }}</ref> Kediet ej Jill, the highest mountain of Mauritania, is made entirely of the mineral.<ref>''European Space Agency'', [https://www.esa.int/Applications/Observing_the_Earth/Earth_from_Space_Eye_of_Africa esa.int] (access: August 2 2020)</ref> Deposits are also found in {{wipe|Norway}}, Romania, and {{wipe|Ukraine}}.{{sfn|Hurlbut|Klein|1985|p=388}} Magnetite-rich sand dunes are found in southern Peru.<ref>{{cite journal |last1=Parker Gay |first1=S |title=Observations regarding the movement of barchan sand dunes in the Nazca to Tanaca area of southern Peru |journal=Geomorphology |date=March 1999 |volume=27 |issue=3–4 |pages=279–293 |doi=10.1016/S0169-555X(98)00084-1|bibcode=1999Geomo..27..279P }}</ref> In 2005, an exploration company, Cardero Resources, discovered a vast deposit of magnetite-bearing sand dunes in Peru. The dune field covers 250 square kilometers (100&nbsp;sq&nbsp;mi), with the highest dune at over 2,000 meters (6,560&nbsp;ft) above the desert floor. The sand contains 10% magnetite.<ref>{{cite news |last1=Moriarty |first1=Bob |title=Ferrous Nonsnotus |date=5 July 2005 |url=http://www.321gold.com/editorials/moriarty/moriarty070505.html |website=321gold |access-date=15 November 2018}}</ref>

In large enough quantities magnetite can affect [[Physics:Compass|compass]] [[Earth:Navigation|navigation]]. In Tasmania there are many areas with highly magnetized rocks that can greatly influence compasses. Extra steps and repeated observations are required when using a compass in Tasmania to keep navigation problems to the minimum.<ref>{{Cite web|url=https://eprints.utas.edu.au/13644/1/1997_Leaman_Magnetic_rst.pdf|title=Magnetic Rocks - Their Effect on Compass Use and Navigation in Tasmania|last=Leaman|first=David|access-date=2018-03-23|archive-date=2017-03-29|archive-url=https://web.archive.org/web/20170329165541/http://eprints.utas.edu.au/13644/1/1997_Leaman_Magnetic_rst.pdf|url-status=dead}}</ref>

Magnetite crystals with a [[Cube|cubic]] habit are rare but have been found at Balmat, St. Lawrence County, New York,<ref>{{cite journal |last1=Chamberlain |first1=Steven C. |last2=Robinson |first2=George W. |last3=Lupulescu |first3=Marian |last4=Morgan |first4=Timothy C. |last5=Johnson |first5=John T. |last6=deLorraine |first6=William B. |title=Cubic and Tetrahexahedral Magnetite |journal=Rocks & Minerals |date=May 2008 |volume=83 |issue=3 |pages=224–239 |doi=10.3200/RMIN.83.3.224-239|s2cid=129227218 }}</ref><ref name="minerals">{{cite web|title=The mineral Magnetite |url=http://www.minerals.net/mineral/magnetite.aspx|website=Minerals.net}}</ref> and at [[Earth:Långban|Långban, Sweden]].<ref>{{cite journal |last1=Boström |first1=Kurt |title=Magnetite Crystals of Cubic Habit from Långban, Sweden |journal=Geologiska Föreningen i Stockholm Förhandlingar |date=15 December 1972 |volume=94 |issue=4 |pages=572–574 |doi=10.1080/11035897209453690}}</ref> This habit may be a result of crystallization in the presence of cations such as zinc.<ref>{{cite journal |last1=Clark |first1=T.M. |last2=Evans |first2=B.J. |title=Influence of chemical composition on the crystalline morphologies of magnetite |journal=IEEE Transactions on Magnetics |date=1997 |volume=33 |issue=5 |pages=4257–4259 |doi=10.1109/20.619728|bibcode=1997ITM....33.4257C |s2cid=12709419 }}</ref>

Magnetite can also be found in [[Biology:Fossil|fossil]]s due to [[Earth:Biomineralization|biomineralization]] and are referred to as [[Biology:Magnetofossil|magnetofossil]]s.<ref>{{cite journal |last1=Chang |first1=S. B. R. |last2=Kirschvink |first2=J. L. |title=Magnetofossils, the Magnetization of Sediments, and the Evolution of Magnetite Biomineralization |journal=Annual Review of Earth and Planetary Sciences |date=May 1989 |volume=17 |issue=1 |pages=169–195 |doi=10.1146/annurev.ea.17.050189.001125 |url=http://web.gps.caltech.edu/~jkirschvink/pdfs/AnnualReviews89.pdf |access-date=15 November 2018|bibcode=1989AREPS..17..169C }}</ref> There are also instances of magnetite with origins in [[Astronomy:Outer space|space]] coming from [[Astronomy:Meteorite|meteorite]]s.<ref>{{cite journal |last1=Barber |first1=D. J. |last2=Scott |first2=E. R. D. |title=Origin of supposedly biogenic magnetite in the Martian meteorite Allan Hills 84001 |journal=Proceedings of the National Academy of Sciences |date=14 May 2002 |volume=99 |issue=10 |pages=6556–6561 |doi=10.1073/pnas.102045799|pmid=12011420 |pmc=124441 |bibcode=2002PNAS...99.6556B |doi-access=free }}</ref>

==Biological occurrences==
[[Physics:Biomagnetism|Biomagnetism]] is usually related to the presence of biogenic crystals of magnetite, which occur widely in organisms.<ref name=Magnetite-based_magnetoreception>{{ cite journal |last1 = Kirschvink |first1 = J L |last2 = Walker |first2 = M M |last3 = Diebel |first3 = C E |title = Magnetite-based magnetoreception. |journal = Current Opinion in Neurobiology |pmid = 11502393 |pages = 462–7 |issue = 4 |volume = 11 |year = 2001 |doi=10.1016/s0959-4388(00)00235-x|s2cid = 16073105 }}</ref> These organisms range from [[Physics:Magnetotactic bacteria|magnetotactic bacteria]] (e.g., ''Magnetospirillum magnetotacticum'') to animals, including humans, where magnetite crystals (and other magnetically sensitive compounds) are found in different organs, depending on the species.<ref name=PMID_25587420/><ref name=Kirschvink_1992>{{ cite journal |last1 = Kirschvink |first1 = Joseph |display-authors = etal|year = 1992 |title = Magnetite biomineralization in the human brain |journal = Proceedings of the National Academy of Sciences of the USA |quote = Using an ultrasensitive superconducting magnetometer in a clean-lab environment, we have detected the presence of ferromagnetic material in a variety of tissues from the human brain. |pages = 7683–7687 |issue = 16 |volume = 89 |doi=10.1073/pnas.89.16.7683|bibcode = 1992PNAS...89.7683K |pmid = 1502184 |pmc = 49775 |doi-access = free }}</ref>  Biomagnetites account for the effects of weak magnetic fields on biological systems.<ref name=Mechanism_for_biological_effects>{{ cite journal |last1 = Kirschvink |first1 = J L |last2 = Kobayashi-Kirschvink |first2 = A |last3 = Diaz-Ricci |first3 = J C |last4 = Kirschvink |first4 = S J |year = 1992 |title = Magnetite in human tissues: a mechanism for the biological effects of weak ELF magnetic fields. |journal = Bioelectromagnetics |quote = A simple calculation shows that magnetosomes moving in response to earth-strength ELF fields are capable of opening trans-membrane ion channels, in a fashion similar to those predicted by ionic resonance models. Hence, the presence of trace levels of biogenic magnetite in virtually all human tissues examined suggests that similar biophysical processes may explain a variety of weak field ELF bioeffects. |pmid = 1285705 |pages = 101–13 |volume = Suppl 1 |doi = 10.1002/bem.2250130710 |citeseerx = 10.1.1.326.4179 }}</ref> There is also a chemical basis for cellular sensitivity to electric and magnetic fields (galvanotaxis).<ref name=galvanotaxis>{{ cite journal |last1 = Nakajima |first1 = Ken-ichi |last2 = Zhu |first2 = Kan |last3 = Sun |first3 = Yao-Hui |last4 = Hegyi |first4 = Bence |last5 = Zeng |first5 = Qunli |last6 = Murphy |first6 = Christopher J |last7 = Small |first7 = J Victor |last8 = Chen-Izu |first8 = Ye |last9 = Izumiya |first9 = Yoshihiro |last10 = Penninger |first10 = Josef M |last11 = Zhao |first11 = Min |year = 2015 |title = KCNJ15/Kir4.2 couples with polyamines to sense weak extracellular electric fields in galvanotaxis |journal = Nature Communications |quote = Taken together these data suggest a previously unknown two-molecule sensing mechanism in which KCNJ15/Kir4.2 couples with polyamines in sensing weak electric fields. |doi = 10.1038/ncomms9532|pmid = 26449415 |pages = 8532 |volume = 6 |pmc=4603535|bibcode = 2015NatCo...6.8532N }}</ref>

[[File:Magnetite magnetosomes in Gammaproteobacteria.png|thumb|upright=1.5|Magnetite magnetosomes in [[Biology:Gammaproteobacteria|Gammaproteobacteria]]]]Pure magnetite particles are biomineralized in magnetosomes, which are produced by several species of magnetotactic bacteria. Magnetosomes consist of long chains of oriented magnetite particle that are used by bacteria for navigation. After the death of these bacteria, the magnetite particles in magnetosomes may be preserved in sediments as magnetofossils. Some types of [[Biology:Anaerobic organism|anaerobic bacteria]] that are not magnetotactic can also create magnetite in oxygen free sediments by reducing amorphic ferric oxide to magnetite.<ref>{{cite web|last1=Lovley|first1=Derek|last2=Stolz|first2=John|last3=Nord|first3=Gordon|last4=Phillips|first4=Elizabeth|title=Anaerobic production of magnetite by a dissimilatory iron-reducing microorganism|url=http://www.geobacter.org/publication-files/Nature_1987_Nov.pdf|website=geobacter.org|publisher=US Geological Survey, Reston, Virginia 22092, USA Department of Biochemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA|access-date=9 February 2018|archive-date=29 March 2017|archive-url=https://web.archive.org/web/20170329151927/http://www.geobacter.org/publication-files/Nature_1987_Nov.pdf|url-status=dead}}</ref>

Several species of birds are known to incorporate magnetite crystals in the upper beak for [[Physics:Magnetoreception|magnetoreception]],<ref name=Magnetoreception_review>{{ cite journal |last1 = Kishkinev |first1 = D A |last2 = Chernetsov |first2 = N S |year = 2014 |title = [Magnetoreception systems in birds: a review of current research] |journal = Zhurnal Obshcheĭ Biologii |quote = There are good reasons to believe that this visual magnetoreceptor processes compass magnetic information which is necessary for migratory orientation. |pages = 104–23 |issue = 2 |volume = 75 |pmid = 25490840}}</ref> which (in conjunction with cryptochromes in the [[Biology:Retina|retina]]) gives them the ability to sense the direction, polarity, and magnitude of the ambient [[Physics:Magnetic field|magnetic field]].<ref name=PMID_25587420>{{ cite journal |last1 = Wiltschko |first1 = Roswitha |last2 = Wiltschko |first2 = Wolfgang |year = 2014 |title = Sensing magnetic directions in birds: radical pair processes involving cryptochrome |journal = Biosensors |quote = Birds can use the geomagnetic field for compass orientation. Behavioral experiments, mostly with migrating passerines, revealed three characteristics of the avian magnetic compass: (1) it works spontaneously only in a narrow functional window around the intensity of the ambient magnetic field, but can adapt to other intensities, (2) it is an "inclination compass", not based on the polarity of the magnetic field, but the axial course of the field lines, and (3) it requires short-wavelength light from UV to 565 nm Green. |doi = 10.3390/bios4030221|pmid = 25587420 |pmc = 4264356 |pages = 221–42 |issue = 3 |volume = 4 |doi-access = free }}</ref><ref name=Magnetic_inclination_avian_navigation>{{ cite journal |last1 = Wiltschko |first1 = Roswitha |last2 = Stapput |first2 = Katrin |last3 = Thalau |first3 = Peter |last4 = Wiltschko |first4 = Wolfgang |year = 2010 |title = Directional orientation of birds by the magnetic field under different light conditions. |journal = Journal of the Royal Society, Interface |quote = Compass orientation controlled by the inclination compass ...allows birds to locate courses of different origin |doi = 10.1098/rsif.2009.0367.focus|pmid = 19864263 |pages = S163–77 |issue = Suppl 2 |volume = 7 |pmc=2843996}}</ref>

Chitons, a type of mollusk, have a tongue-like structure known as a [[Biology:Radula|radula]], covered with magnetite-coated teeth, or denticles.<ref name=Chitons>{{ cite journal |author= Lowenstam, H.A. |year = 1967|title = Lepidocrocite, an apatite mineral, and magnetic in teeth of chitons (Polyplacophora) |journal = Science  |pmid = 5610118 |pages = 1373–1375 |issue = 3780 |volume = 156 | quote = X-ray diffraction patterns show that the mature denticles of three extant chiton species are composed of the mineral lepidocrocite and an apatite mineral, probably francolite, in addition to magnetite. |doi=10.1126/science.156.3780.1373|bibcode = 1967Sci...156.1373L |s2cid = 40567757|}}</ref> The hardness of the magnetite helps in breaking down food.

Biological magnetite may store information about the magnetic fields the organism was exposed to, potentially allowing scientists to learn about the migration of the organism or about changes in the Earth's magnetic field over time.<ref name="Bókkon">{{ cite journal |last1 = Bókkon |first1 = Istvan |last2 = Salari |first2 = Vahid |year = 2010 |title = Information storing by biomagnetites |journal = Journal of Biological Physics |doi = 10.1007/s10867-009-9173-9|pmid = 19728122 |pages = 109–20 |issue = 1 |volume = 36 |pmc=2791810|bibcode = 2010arXiv1012.3368B |arxiv = 1012.3368 }}</ref>

===Human brain===
Living organisms can produce magnetite.<ref name=Kirschvink_1992/> In humans, magnetite can be found in various parts of the brain including the [[Biology:Frontal lobe|frontal]], [[Biology:Parietal lobe|parietal]], [[Biology:Occipital lobe|occipital]], and [[Biology:Temporal lobe|temporal lobe]]s, [[Biology:Brainstem|brainstem]], [[Biology:Cerebellum|cerebellum]] and [[Biology:Basal ganglia|basal ganglia]].<ref name=Kirschvink_1992/><ref name="ReferenceA">Magnetite Nano-Particles in Information Processing: From the Bacteria to the Human Brain Neocortex - {{ISBN|9781-61761-839-0}}</ref> Iron can be found in three forms in the brain – magnetite, hemoglobin (blood) and [[Biology:Ferritin|ferritin]] (protein), and areas of the brain related to motor function generally contain more iron.<ref name="ReferenceA"/><ref name="Zecca2004">{{cite journal |author1=Zecca, Luigi |author2=Youdim, Moussa B. H. |author3=Riederer, Peter |author4=Connor, James R. |author5=Crichton, Robert R. |title=Iron, brain ageing and neurodegenerative disorders |journal=Nature Reviews Neuroscience |year=2004 |volume=5 |issue=11 |pages=863–873 |doi=10.1038/nrn1537 |pmid=15496864 |s2cid=205500060 }}</ref> Magnetite can be found in the [[Biology:Hippocampus|hippocampus]]. The hippocampus is associated with information processing, specifically learning and memory.<ref name="ReferenceA"/> However, magnetite can have toxic effects due to its charge or magnetic nature and its involvement in oxidative stress or the production of [[Biology:Free radical|free radical]]s.<ref name="ReferenceB">{{cite journal |title=Magnetite pollution nanoparticles in the human brain |author1=Barbara A. Maher |author2=Imad A. M. Ahmed |author3=Vassil Karloukovski |author4=Donald A. MacLaren |author5=Penelope G. Foulds |author6=David Allsop |author7=David M. A. Mann |author8=Ricardo Torres-Jardón |author9=Lilian Calderon-Garciduenas |journal=PNAS |volume=113 |issue=39 |pages=10797–10801 |doi=10.1073/pnas.1605941113 |pmid=27601646 |pmc=5047173 |year=2016 |bibcode=2016PNAS..11310797M |doi-access=free }}</ref> Research suggests that beta-amyloid plaques and [[Biology:Tau protein|tau protein]]s associated with [[Medicine:Neurodegenerative disease|neurodegenerative disease]] frequently occur after oxidative stress and the build-up of iron.<ref name="ReferenceA"/>

Some researchers also suggest that humans possess a magnetic sense,<ref name="Human_magnetoreception">{{cite journal |url=https://www.science.org/content/article/maverick-scientist-thinks-he-has-discovered-magnetic-sixth-sense-humans-rev2 |title=Maverick scientist thinks he has discovered a magnetic sixth sense in humans |author=Eric Hand |date=June 23, 2016 |journal=Science |doi=10.1126/science.aaf5803}}</ref> proposing that this could allow certain people to use magnetoreception for navigation.<ref name=human_magnetoreception>{{ cite journal |last1 = Baker |first1 = R R |year = 1988 |title = Human magnetoreception for navigation |journal = Progress in Clinical and Biological Research |pmid = 3344279 |pages = 63–80 |volume = 257 }}</ref> The role of magnetite in the brain is still not well understood, and there has been a general lag in applying more modern, interdisciplinary techniques to the study of biomagnetism.<ref name=PMID_20071390>{{ cite journal |last1 = Kirschvink |first1 = Joseph L |last2 = Winklhofer |first2 = Michael |last3 = Walker |first3 = Michael M |year = 2010 |title = Biophysics of magnetic orientation: strengthening the interface between theory and experimental design. |journal = Journal of the Royal Society, Interface |doi = 10.1098/rsif.2009.0491.focus|pmid = 20071390 |pages = S179–91 |volume = 7 |issue = Suppl 2 |pmc=2843999}}</ref>

[[Engineering:Electron microscope|Electron microscope]] scans of human brain-tissue samples are able to differentiate between magnetite produced by the body's own cells and magnetite absorbed from airborne pollution, the natural forms being jagged and crystalline, while magnetite pollution occurs as rounded [[Physics:Nanoparticle|nanoparticle]]s. Potentially a human health hazard, airborne magnetite is a result of pollution (specifically combustion). These nanoparticles can travel to the brain via the olfactory nerve, increasing the concentration of magnetite in the brain.<ref name="ReferenceA"/><ref name="ReferenceB"/> In some brain samples, the nanoparticle pollution outnumbers the natural particles by as much as 100:1, and such pollution-borne magnetite particles may be linked to abnormal neural deterioration. In one study, the characteristic nanoparticles were found in the brains of 37 people: 29 of these, aged 3 to 85, had lived and died in Mexico City, a significant air pollution hotspot. Some of the further eight, aged 62 to 92, from Manchester, England, had died with varying severities of neurodegenerative diseases.<ref>{{Cite news|url=https://www.bbc.com/news/science-environment-37276219|title=Pollution particles 'get into brain'|work=BBC News|date=September 5, 2016}}</ref> Such particles could conceivably contribute to diseases like [[Medicine:Alzheimer's disease|Alzheimer's disease]].<ref>{{cite journal |last1=Maher |first1=B.A. |last2=Ahmed |first2=I.A. |last3=Karloukovski |first3=V. |last4=MacLaren |first4=D.A. |last5=Foulds |first5=P.G. |last6=Allsop |first6=D. |last7=Mann |first7=D.M. |last8=Torres-Jardón |first8=R.  |last9=Calderon-Garciduenas |first9=L. |year=2016 |title=Magnetite pollution nanoparticles in the human brain |journal=Proceedings of the National Academy of Sciences |volume=113 |number=39 |pages=10797–10801 |doi=10.1073/pnas.1605941113|pmid=27601646 |pmc=5047173 |bibcode=2016PNAS..11310797M |doi-access=free }}</ref> Though a causal link has not yet been established, laboratory studies suggest that iron oxides such as magnetite are a component of [[Medicine:Senile plaques|protein plaques]] in the brain. Such plaques have been linked to [[Medicine:Alzheimer's disease|Alzheimer's disease]].<ref>{{cite journal|last1=Wilson|first1=Clare|title=Air pollution is sending tiny magnetic particles into your brain|journal=New Scientist|date=5 September 2016 |volume=231 |issue=3090 |url=https://www.newscientist.com/article/2104654-air-pollution-is-sending-tiny-magnetic-particles-into-your-brain/|access-date=6 September 2016}}</ref>

Increased iron levels, specifically magnetic iron, have been found in portions of the brain in Alzheimer's patients.<ref name="Qin, Y. 2011">{{cite journal |last1=Qin |first1=Yuanyuan |last2=Zhu |first2=Wenzhen |last3=Zhan |first3=Chuanjia |last4=Zhao |first4=Lingyun |last5=Wang |first5=Jianzhi |last6=Tian |first6=Qing |last7=Wang |first7=Wei |title=Investigation on positive correlation of increased brain iron deposition with cognitive impairment in Alzheimer disease by using quantitative MR R2′ mapping |journal=Journal of Huazhong University of Science and Technology [Medical Sciences] |date=August 2011 |volume=31 |issue=4 |pages=578–585 |doi=10.1007/s11596-011-0493-1|pmid=21823025 |s2cid=21437342 }}</ref> Monitoring changes in iron concentrations may make it possible to detect the loss of neurons and the development of neurodegenerative diseases prior to the onset of symptoms<ref name="Zecca2004"/><ref name="Qin, Y. 2011"/> due to the relationship between magnetite and [[Biology:Ferritin|ferritin]].<ref name="ReferenceA"/> In tissue, magnetite and ferritin can produce small magnetic fields which will interact with [[Physics:Magnetic resonance imaging|magnetic resonance imaging]] (MRI) creating contrast.<ref name="Qin, Y. 2011"/> Huntington patients have not shown increased magnetite levels; however, high levels have been found in study mice.<ref name="ReferenceA"/>

==Applications==
Due to its high iron content, magnetite has long been a major [[Earth:Iron ore|iron ore]].<ref>Franz Oeters et al"Iron" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a14_461.pub2}}</ref>  It is reduced in blast furnaces to [[Chemistry:Pig iron|pig iron]] or sponge iron for conversion to steel.<ref>{{cite book |last1=Davis |first1=E.W. |year=2004 |title=Pioneering with taconite |publisher=Minnesota Historical Society Press |isbn=0873510232}}</ref>

===Magnetic recording===
Audio recording using magnetic acetate tape was developed in the 1930s. The German magnetophon first utilized magnetite powder that BASF coated onto cellulose acetate before soon switching to gamma ferric oxide for its superior morphology.<ref name= Schoenherr>{{cite web| url= http://www.aes.org/aeshc/docs/recording.technology.history/magnetic4.html | last= Schoenherr | first =Steven | date =2002 |title =The History of Magnetic Recording |publisher= Audio Engineering Society}}</ref>  Following [[Social:World War II|World War II]],  [[Company:3M|3M]] Company continued work on the German design. In 1946, the 3M researchers found they could also improve their own magnetite-based paper tape, which utilized powders of cubic crystals, by replacing the magnetite with needle-shaped particles of [[Chemistry:Iron(III) oxide#Gamma phase|gamma ferric oxide]] (γ-Fe<sub>2</sub>O<sub>3</sub>).<ref name=Schoenherr/>

===Catalysis===
Approximately 2–3% of the world's energy budget is allocated to the Haber Process for nitrogen fixation, which relies on magnetite-derived catalysts. The industrial catalyst is obtained from finely ground iron powder, which is usually obtained by reduction of high-purity magnetite. The pulverized iron metal is burnt (oxidized) to give magnetite or wüstite of a defined particle size. The magnetite (or wüstite) particles are then partially reduced, removing some of the [[Chemistry:Oxygen|oxygen]] in the process. The resulting catalyst particles consist of a core of magnetite, encased in a shell of wüstite, which in turn is surrounded by an outer shell of iron metal. The catalyst maintains most of its bulk volume during the reduction, resulting in a highly porous high-surface-area material, which enhances its effectiveness as a catalyst.<ref name="jozwiak">{{cite journal | last1 = Jozwiak | first1 = W. K. | last2 = Kaczmarek | first2 = E. | display-authors = etal | year = 2007 | title = Reduction behavior of iron oxides in hydrogen and carbon monoxide atmospheres | journal = Applied Catalysis A: General | volume = 326 | pages = 17–27 | doi = 10.1016/j.apcata.2007.03.021 }}</ref><ref name=Appl>{{Ullmann |first=Max |last=Appl |title=Ammonia |doi=10.1002/14356007.a02_143.pub2 |year=2006}}</ref>

=== Magnetite nanoparticles ===
Magnetite micro- and nanoparticles are used in a variety of applications, from biomedical to environmental. One use is in water purification: in high gradient magnetic separation, magnetite nanoparticles introduced into contaminated water will bind to the suspended particles (solids, bacteria, or plankton, for example) and settle to the bottom of the fluid, allowing the contaminants to be removed and the magnetite particles to be recycled and reused.<ref name=":0">{{Cite journal |last=Blaney |first=Lee |date=2007 |title=Magnetite (Fe3O4): Properties, Synthesis, and Applications |url=https://preserve.lehigh.edu/cas-lehighreview-vol-15/5/ |journal=The Lehigh Review |volume=15 |issue=5 |language=en |access-date=2017-12-15 |archive-date=2020-11-11 |archive-url=https://web.archive.org/web/20201111154629/https://preserve.lehigh.edu/cas-lehighreview-vol-15/5/ |url-status=dead }}</ref> This method works with radioactive and carcinogenic particles as well, making it an important cleanup tool in the case of heavy metals introduced into water systems.<ref>{{Cite journal|last1=Rajput|first1=Shalini|last2=Pittman|first2=Charles U.|last3=Mohan|first3=Dinesh|title=Magnetic magnetite (Fe 3 O 4 ) nanoparticle synthesis and applications for lead (Pb 2+ ) and chromium (Cr 6+ ) removal from water|journal=Journal of Colloid and Interface Science|language=en|volume=468|pages=334–346 |doi=10.1016/j.jcis.2015.12.008|pmid=26859095|year=2016|bibcode=2016JCIS..468..334R}}</ref> 

Another application of magnetic nanoparticles is in the creation of [[Physics:Ferrofluid|ferrofluid]]s. These are used in several ways. Ferrofluids can be used for targeted [[Medicine:Drug delivery|drug delivery]] in the human body.<ref name=":0" /> The magnetization of the particles bound with drug molecules allows "magnetic dragging" of the solution to the desired area of the body. This would allow the treatment of only a small area of the body, rather than the body as a whole, and could be highly useful in cancer treatment, among other things. Ferrofluids are also used in [[Physics:Magnetic resonance imaging|magnetic resonance imaging]] (MRI) technology.<ref>{{Cite journal|last1=Stephen|first1=Zachary R.|last2=Kievit|first2=Forrest M.|last3=Zhang|first3=Miqin|title=Magnetite nanoparticles for medical MR imaging|journal=Materials Today|language=en|volume=14|issue=7–8|pages=330–338|doi=10.1016/s1369-7021(11)70163-8|pmid=22389583|pmc=3290401|year=2011}}</ref>

===Coal mining industry===
For the separation of coal from waste, dense medium baths were used. This technique employed the difference in densities between [[Earth:Coal|coal]] (1.3–1.4 tonnes per m<sup>3</sup>) and shales (2.2–2.4 tonnes per m<sup>3</sup>). In a medium with intermediate [[Physics:Density|density]] (water with magnetite), stones sank and coal floated.<ref>{{cite journal |last1=Nyssen |first1=J |last2=Diependaele |first2=S |last3=Goossens |first3=R |title=Belgium's burning coal tips - coupling thermographic ASTER imagery with topography to map debris slide susceptibility |journal=Zeitschrift für Geomorphologie |date=2012 |volume=56 |issue=1 |pages=23–52|doi=10.1127/0372-8854/2011/0061 |bibcode=2012ZGm....56...23N }}</ref>

==Magnetene==
Magnetene is a two-dimensional flat sheet of magnetite noted for its ultra-low-friction properties.<ref>{{Cite web|url=https://phys.org/news/2021-11-magnetene-graphene-like-2d-material-leverages.html|title=Magnetene: Graphene-like 2D material leverages quantum effects to achieve ultra-low friction|first=University of|last=Toronto|website=phys.org}}</ref>

==Gallery==
<gallery widths="150px" heights="150px">
File:Magnetite-278427.jpg|Octahedral crystals of magnetite up to 1.8&nbsp;cm across, on cream colored [[Chemistry:Feldspar|feldspar]] crystals, locality: Cerro Huañaquino, Potosí Department, Bolivia
File:Magnetite-170591.jpg|Magnetite crystals with epitaxial elevations on their faces
File:Chalcopyrite-Magnetite-cktsr-10c.jpg|Magnetite in contrasting [[Chemistry:Chalcopyrite|chalcopyrite]] matrix
File:Magnetite-rw16b.jpg|Magnetite with a rare cubic habit from St. Lawrence County, New York
</gallery>

==See also==
* [[Engineering:Bluing (steel)|Bluing (steel)]], a process in which steel is partially protected against rust by a layer of magnetite
* Buena Vista Iron Ore District
* [[Chemistry:Corrosion|Corrosion]] product
* [[Physics:Ferrite (magnet)|Ferrite]]
* [[Chemistry:Greigite|Greigite]]
* Magnesia (in natural mixtures with magnetite)
* [[Chemistry:Mill scale|Mill scale]]
* [[Physics:Magnes the shepherd|Magnes the shepherd]]
* [[Chemistry:Rainbow lattice sunstone|Rainbow lattice sunstone]]

==References==
{{reflist|30em}}

==Further reading==
*{{cite book|last = Lowenstam|first = Heinz A.|author2=Weiner, Stephen|title = On Biomineralization|publisher = Oxford University Press|year = 1989|location = USA|isbn = 978-0-19-504977-0}}
*{{cite journal|last = Chang|first = Shih-Bin Robin|author2=Kirschvink, Joseph Lynn|title = Magnetofossils, the Magnetization of Sediments, and the Evolution of Magnetite Biomineralization|journal = Annual Review of Earth and Planetary Sciences|volume = 17|pages = 169–195|year = 1989|url = http://www.gps.caltech.edu/~jkirschvink/pdfs/AnnualReviews89.pdf|doi = 10.1146/annurev.ea.17.050189.001125|bibcode = 1989AREPS..17..169C }}

==External links==
*[http://www.galleries.com/minerals/oxides/magnetit/magnetit.htm Mineral galleries] {{Webarchive|url=https://web.archive.org/web/20110207080134/http://www.galleries.com/minerals/oxides/magnetit/magnetit.htm |date=2011-02-07 }}
*[http://www.astronomycafe.net/qadir/ask/a11651.html Bio-magnetics]
*[https://web.archive.org/web/20121119180010/http://www.nzpam.govt.nz/cms/minerals/overview/overview?searchterm=ironsand Magnetite mining in New Zealand] Accessed 25-Mar-09

{{ores}}


[[Category:Iron(II,III) minerals]]
[[Category:Spinel group]]
[[Category:Ferromagnetic materials]]
[[Category:Cubic minerals]]
[[Category:Iron ores]]
[[Category:Magnetic minerals]]
[[Category:Ferrites]]

{{Sourceattribution|Magnetite}}