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Magnetite

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Formula:
Fe
2+
 
Fe
3+
2
O
 
4
System:IsometricColour:Greyish black or iron ...
Lustre:Metallic, Sub-MetallicHardness:5½ - 6½
Member of:Spinel Group
Name:Originally called lodestone as early as 1548 and by other names. Named in 1845 by Wilhelm Karl von Haidinger for the locality at Magnesia, Greece (site for lodestone).


Spinel Group, Jacobsite-Magnetite Series. Magnesioferrite-Magnetite Series.

Magnetite is an important iron ore, along with hematite.

Nanoinclusions of magnetite crystals cause the iridescence of Rainbow obsidian (Nadin, 2007). Extremely thin layers of 200-nm octahedral crystals of magnetite give some basalt surfaces an iridescent sheen (Nadin, 2007).

Visit gemdat.org for gemological information about Magnetite. Currently in public beta-test.

Classification of Magnetite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/B.02-20
Nickel-Strunz 10th (pending) edition ID:4.BB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
B : With only medium-sized cations
Dana 8th edition ID:7.2.2.3

7 : MULTIPLE OXIDES
2 : AB2X4
Hey's CIM Ref.:7.20.2

7 : Oxides and Hydroxides
20 : Oxides of Fe
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Occurrences of Magnetite

Geological Setting:Common igneous accessory mineral. In sedimentary banded iron formations.

Physical Properties of Magnetite

Lustre:Metallic, Sub-Metallic
Diaphaneity (Transparency):Opaque
Colour:Greyish black or iron black
Streak:Black
Hardness (Mohs):5½ - 6½
Hardness (Vickers):VHN100=681 - 792 kg/mm2
Tenacity:Brittle
Parting:On {111}, especially good. Also reported as parting planes: {001}, {011}, {138}.
Fracture:Irregular/Uneven
Density (measured):5.175 g/cm3
Density (calculated):5.2 g/cm3

Crystallography of Magnetite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fd3m {F41/d 3 2/m}
Cell Parameters:a = 8.397Å
Unit Cell Volume:V 592.07 ų (Calculated from Unit Cell)
Z:8
Morphology:Crystals usually octahedral, sometimes dodecahedral, striated on {011} parallel [011]; less frequently with modifying {001} or {hhl}. Cubic (Balmat, NY), rare. Skeletonized microcrystals found in igneous rocks. Massive, granular, coarse to fine.
Twinning:Common on {111}, with the same face as the composition face. Twins flattened parallel to {111} (common spinel law twins), or as lamellar twins, producing striae on {111}. Twin gliding, with K1{111}, K2{111}.
Crystal Atlas:
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Magnetite no.3 - Goldschmidt (1913-1926)
Magnetite no.30 - Goldschmidt (1913-1926)
Magnetite no.37 - Goldschmidt (1913-1926)
Magnetite no.53 - Goldschmidt (1913-1926)
Magnetite no.91 - Goldschmidt (1913-1926)
Magnetite no.92 - Goldschmidt (1913-1926)

About Crystal Atlas

The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. The 3d models and HTML5 code are kindly provided by www.smorf.nl.

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Epitaxial Relationships of Magnetite

Epitaxial Minerals:
Rutile
TiO
 
2
Rutile
TiO
 
2
Pyrophanite
Mn
2+
 
TiO
 
3
Olivine
(Mg,Fe
2+
 
)
 
2
SiO
 
4
Muscovite
KAl
 
2
(AlSi
 
3
O
 
10
)(OH)
 
2
Ilmenite
Fe
2+
 
TiO
 
3
Hematite
Fe
 
2
O
 
3
Epitaxi Comments:Hematite overgrowths on, and inclusions in, magnetite; ilmenite inclusions, rutile overgrowths, chorite group overgrowths, pyrophanite inclusions; magnetite on hematite; inclusions in muscovite; inclusions in hematite; inclusions in ilmenite; magnetite overgrowths on olivine
X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
4.852 (8)
2.967 (30)
2.5432 (100)
2.424 (8)
2.099 (20)
1.7146 (10)
1.6158 (30)
1.4845 (40)
1.2807 (10)
1.0930 (12)
0.85690 (8)
Comments:Only d-spacings with I>8 given.

Optical Data of Magnetite

Type:Isotropic
RI values: n = 2.42
Maximum Birefringence:δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:Very High
Colour in reflected light:Grey with brownish tint
Internal Reflections:None
Comments:Twin lamellae and zonal growth pattern exhibited in polished section by magnetite at times.

Chemical Properties of Magnetite

Formula:
Fe
2+
 
Fe
3+
2
O
 
4
Simplified for copy/paste:Fe2+Fe3+2O4
Essential elements:Fe, O
All elements listed in formula:Fe, O
Common Impurities:Mg,Zn,Mn,Ni,Cr,Ti,V,Al

Relationship of Magnetite to other Species

Series:Forms a series with Magnesioferrite (see here)
Forms a series with Jacobsite (see here)
Forms a series with Chromite (see here)
Forms a series with Maghemite (see here)
Member of:Spinel Group
Other Members of Group:

- +
Ceylonite
Chromite
Fe
2+
 
Cr
3+
2
O
 
4
Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
Coulsonite
Fe
2+
 
V
3+
2
O
 
4
Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
Filipstadite
(Sb
 
0.5
Fe
 
0.5
)Mn
 
2
O
 
4
Franklinite
Zn
2+
 
Fe
3+
2
O
 
4
Gahnite
ZnAl
 
2
O
 
4
Galaxite
(Mn,Fe,Mg)(Al,Fe)
 
2
O
 
4
Hercynite
Fe
2+
 
Al
 
2
O
 
4
Jacobsite
Mn
2+
 
Fe
3+
2
O
 
4
Magnesiochromite
Mg(Cr,Al,Fe)
 
2
O
 
4
Magnesiocoulsonite
MgV
 
2
O
 
4
Magnesioferrite
MgFe
3+
2
O
 
4
Manganochromite
(Mn,Fe)(Cr,V)
 
2
O
 
4
Nichromite
(Ni,Co,Fe)(Cr,Fe,Al)
 
2
O
 
4
Qandilite
(Mg,Fe)
 
2
(Ti,Fe,Al)O
 
4
Spinel
MgAl
 
2
O
 
4
Trevorite
Ni
2+
 
Fe
3+
2
O
 
4
Ulvöspinel
Fe
 
2
TiO
 
4
Vuorelainenite
(Mn,Fe)(V,Cr)
 
2
O
 
4
Zincochromite
ZnCr
 
2
O
 
4
Related Minerals - Nickel-Strunz Grouping):

- +
4.BB.05Chromite
Fe
2+
 
Cr
3+
2
O
 
4
4.BB.05Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
4.BB.05Coulsonite
Fe
2+
 
V
3+
2
O
 
4
4.BB.05Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
4.BB.05Filipstadite
(Sb
 
0.5
Fe
 
0.5
)Mn
 
2
O
 
4
4.BB.05Franklinite
Zn
2+
 
Fe
3+
2
O
 
4
4.BB.05Gahnite
ZnAl
 
2
O
 
4
4.BB.05Galaxite
(Mn,Fe,Mg)(Al,Fe)
 
2
O
 
4
4.BB.05Hercynite
Fe
2+
 
Al
 
2
O
 
4
4.BB.05Jacobsite
Mn
2+
 
Fe
3+
2
O
 
4
4.BB.05Manganochromite
(Mn,Fe)(Cr,V)
 
2
O
 
4
4.BB.05Magnesiocoulsonite
MgV
 
2
O
 
4
4.BB.05Magnesiochromite
Mg(Cr,Al,Fe)
 
2
O
 
4
4.BB.05Magnesioferrite
MgFe
3+
2
O
 
4
4.BB.05Nichromite
(Ni,Co,Fe)(Cr,Fe,Al)
 
2
O
 
4
4.BB.05Qandilite
(Mg,Fe)
 
2
(Ti,Fe,Al)O
 
4
4.BB.05Spinel
MgAl
 
2
O
 
4
4.BB.05Trevorite
Ni
2+
 
Fe
3+
2
O
 
4
4.BB.05Ulvöspinel
Fe
 
2
TiO
 
4
4.BB.05Vuorelainenite
(Mn,Fe)(V,Cr)
 
2
O
 
4
4.BB.05Zincochromite
ZnCr
 
2
O
 
4
4.BB.10Hausmannite
MnMn
 
2
O
 
4
4.BB.10Hetaerolite
ZnMn
 
2
O
 
4
4.BB.10Hydrohetaerolite
ZnMn
 
2
O
 
4
· H
 
2
O
4.BB.10Iwakiite
Mn(Fe,Mn)
 
2
O
 
4
4.BB.15Maghemite
Fe
3+
2
O
 
3
4.BB.15Titanomaghemite
Fe
3+
 
(Fe
3+
 
,Ti
4+
 
,Fe
2+
 
,◻)
 
2
O
 
4
4.BB.20Tegengrenite
(Mg,Mn
2+
 
)
 
2
Sb
5+
0.5
(Mn
3+
 
,Si,Ti)
 
0.5
O
 
4
4.BB.25Xieite
Fe
2+
 
Cr
 
2
O
 
4
Related Minerals - Hey's Index Grouping:

- +
7.20.1Wüstite
FeO
7.20.3Maghemite
Fe
3+
2
O
 
3
7.20.4Hematite
Fe
 
2
O
 
3
7.20.5Goethite
α-Fe
3+
 
O(OH)
7.20.6Akaganeite
β-Fe
3+
 
O(OH,Cl)
7.20.7Feroxyhyte
Fe
3+
 
O(OH)
7.20.8Lepidocrocite
γ-Fe
3+
 
O(OH)
7.20.9Ferrihydrite
Fe
3+
5
O
 
3
(OH)
 
9
7.20.10Amakinite
(Fe
2+
 
,Mg)(OH)
 
2
7.20.11Magnesioferrite
MgFe
3+
2
O
 
4
7.20.12Muskoxite
Mg
 
7
Fe
 
4
O
 
13
· 10H
 
2
O
7.20.13Srebrodolskite
Ca
 
2
Fe
3+
2
O
 
5
7.20.14Hercynite
Fe
2+
 
Al
 
2
O
 
4
7.20.15Brownmillerite
Ca
 
2
(Al,Fe
3+
 
)
 
2
O
 
5

Other Names for Magnetite

Synonyms:
AimantineDiamagnetiteFerroferriteHeraclionLoadstone
MagnetMagnetic Iron OreMorpholiteOctahedral Iron OreOxydulated Iron
SideritisSyderite
Other Languages:
Arabic:ماغنتيت
Catalan:Magnetita
Croatian:Magnetit
Czech:Magnetit
Dutch:Magnetiet
Estonian:Magnetiit
Finnish:Magnetiitti
French:Magnétite
Aimant
Fer oxydé magnétique
Fer oxydulé
Galician:Magnetita
German:Magnetit
Eisenmohr
Eisenmulm
Eisenoxydoxydul
Ferroferrit
Hammerschlag
Magneteisenerz
Magneteisenstein
Magnetischer Eisenstein
Morpholit
Siegelstein
Syderit
Greek:Μαγνητίτης
Hebrew:מגנטיט
Hungarian:Magnetit
Italian:Magnetite
Ferro magnetico
Ferro ossidolato
Japanese:磁鉄鉱
Latin:Magneti amica
Minera Ferri attractoria
Minera ferri nigricans
Lithuanian:Magnetitas
Norwegian (Bokmål):Magnetitt
Magnetjernstein
Polish:Magnetyt
Portuguese:Magnetita
Romanian:Magnetit
Russian:Магнетит
Serbian (Cyrillic Script):Магнетит
Simplified Chinese:磁铁矿
Slovak:Magnetit
Spanish:Magnetita
Ferroferrita
Hierro magnético
Morpholita
Syderita
Swedish:Magnetit
Magnetjernmalm
Svertmalm
Traditional Chinese:磁鐵礦
Turkish:Manyetit
Ukrainian:Магнетит
Varieties:
Aluminous MagnetiteChrommagnetiteHydromagnetiteIshkuliteLodestone
ManganmagnetiteMg-TitanomagnetiteMushketoviteNickeloan MagnetiteSilfbergite (of Niggli)
Titaniferous MagnetiteVanado-Magnetite

Other Information

Magnetism:Ferromagnetic
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:Ore of iron.

References for Magnetite

Reference List:

- +
Mügge (1905), Jb. Min., Beil.-Bd.: 16: 335.

Bragg (1915), Nature: 95: 561.

Bragg (1915), Phl. Magazine: 30: 305.

Greig, Merwin, and Posnjak (1936), American Mineralogist: 21: 504.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 698-707.

Schneiderhöhn (1958): I: 226-287.

Buddington, A.F. and Lindsley, D.H. (1964) Iron-titanium oxide minerals and synthetic equivalents. Journal of Petrology: 5: 310-357.

Johnson, H.P. and Merrill, R.T. (1972) Magnetic and mineralogical changes associated with low-temperature oxidation of magnetite. Journal of Geophysical Research: 77: 334-341.

Neumann, E.-R. (1974) The distribution of Mn 2+ and Fe 2+ between ilmenites and magnetites in igneous rocks. American Journal of Science: 274: 1074-1088.

Mao, H.K., D. Virgo, & P.M. Bell (1977), High-pressure 57Fe Mössbauer data on the phase and magnetic transitions of magnesioferrite (MgFe2O4), magnetite (Fe3O4), and hematite (Fe2O3). Carnegie Instsitution of Washington Year Book: 76: 522-525.

Cawthorn, R.G. and McCarthy, TS. (1980) Variations in Cr content of magnetite from the upper zone of the Bushveld complex - Evidence for heterogeneity and convection currents in magma chambers. Earth and Planetary Science Letters: 46: 335-343.

Fleet, M.E., Bilcox, G.A., and Barnett, R.L. (1980) Oriented magnetite inclusions in pyroxenes from the Grenville province. Canadian Mineralogist: 18: 89-99.

Fleet, M.E. (1982b) The structure of magnetite: defect structure II. Ata Crystallographica: B38: 1718-1723.

Fleet, M.E. (1984) The structure of magnetite: two annealed natural magnetites, Fe3.005O4 and Fe2.96Mg0.04O4. Acta Crystallographica (1984): C40: 1491-1493.

Markgraf, S.A., and R.J. Reeder (1985), High-temperature structure refinements of calcite and magnetite: American Mineralogist: 70: 590.

Fleet, M.E. (1986a) The structure of magnetite: symmetry of cubic spinels. Journal of Solid State Chemistry: 62: 75-82.

O'Neill, H.St.C. (1987) The quartz-fayalite-magnetite equilibria and free energies of formation of fayalite (Fe2SiO4) and magnetite (Fe3O4). American Mineralogist: 72: 67-75.

Collyer, S., Grimes, N.W., and Vaughan, D.J. (1988) Does magnetite lack a centre of symmetry? Journal of Physics C (Solid State Physics): 21: L989-L992.

Goss, C.J. (1988) Saturation magnetisation, coercivity and lattice parameter changes in the system Fe3O4-γ-Fe2O3, and their relationship to structure. Physics and Chemistry of Minerals: 16: 164-171.

Cecchini A., Franzini M., Troysi M.(1989): La microdurezza della magnetite. Atti Soc. Tosc. Sc. Nat., Mem., Serie A, 96, 327-332.

Pasternak, M.P., S. Nasu, K. Wada, & S. Endo (1994), High-pressure phase of magnetite: Physical Review B: 50: 6446-6449.

Berti G. (1995): Microstructure of Magnetite from XRPD Data in Relation to Magnetism. Material Science Forum (Trans. Tech. Pub. Zurich Switz.) Vol. 229-231, pp. 431-436.

Kuiper, P., Searle, B.G., Duda, L.-C., Wolf, R.M., and van der Zaag, P.J. (1997) Fe L2,3 linear and circular magnetic dichroism of Fe3O4. Journal of Electron Spectroscopy and Related Phenomena: 86: 107-113.

Coey, J.M.D., Berkowits, A.E., Balcells, L.I., Putris, F.F., and Parker, F.T. (1998) Magnetoresistance of magnetite. Applied Physics Letters: 72: 734-736.

Haavik, C., S. Stølen, H. Fjellvåg, M. Hanfland, & D. Häusermann (2000), Equation of state of magnetite and its high-pressure modification: Thermodynamics of the Fe-O system at high pressure: American Mineralogist: 85: 514-523.

de Castro, A.R.B., Fonesca, P.T., Pacheco, J.G., da Slva, J.C.V., and Santana, M.H.A. (2001) L-edge inner shell spectroscopy of nanostructural Fe3O4. Journal of Magnetism and Magnetic Materials: 233: 69-73.

Wright, J.P., Attfield, J.P., and Radaelli, P.G. (2001) Long range charge ordering in magnetite below the Verwey transition. Physical review Letters: 27: 266401/1-4.

Cornell, R.M. and Schwertmann, U. (2003) The iron oxides. Structure, properties, reactions, occurrences and uses. Wiley-VCH, Weinheim.

Chen, J., Huang, D.J., Tanaka, A., Chang, C.F., Chung, S.C., Wu, W.B., and Chen, C.T. (2004) Magnetic circular dichroism in Fe 2p resonant photoemission of magnetite. Physical Review B, 69, 085107-1-085107-8.

Huang, D.J., Chang, C.F., Jeng, H.-T., Guo, G.Y., Lin, H.-J., W, W.B., Ku, H.C., Fujimori, A., Takahashi, Y., and Chen, C.T. (2004) Spin and orbital magnetic moments of Fe3O4. Physical Review Letters: 93: 077204/1-4.

Lazor, P., O.N. Shebanova, & H. Annersten (2004), High-pressure study of stability of magnetite by thermodynamic analysis and synchrotron X-ray diffraction: Journal of Geophysical Research: 109: B05201.

Pearce, C.I., Henderson, C.M.B., Pattrick, R.A.D., van der Laan, G., and Vaughan, D.J. (2006) Direct determinaton of cation site occupancies in natural ferrite spinels by L 2,3 X-ray absorption spectroscopy and X-ray magnetic circular dichroism. American Mineralogist: 91: 880-893.

Nadin, E. (2007): The secret lives of minerals. Engineering & Science, No. 1, 10-20.

Mindat.org articles about Magnetite

Article entries:
Iron Mines of Iron Co. UtahDave Crosby

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Best of Species:Magnetite

Internet Links for Magnetite

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    Localities for Magnetite

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