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Magnetite

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Mineville, Moriah Township, Mineville District, Essex Co., New York, USA
© 2001 John H. Betts

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Formula:
Fe
2+
 
Fe
3+
2
O
 
4
System:IsometricColour:Greyish black or iron ...
Lustre:Metallic, Sub-MetallicHardness:5½ - 6½
Name:Named for locality of Magnesia, Greece (site for lodestone).


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

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

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Epitaxial Relationships of Magnetite

Epitaxial Minerals:
RutileRutilePyrophaniteOlivineMuscovite
IlmeniteHematite
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: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

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
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)
Related Minerals - Nickel-Strunz Grouping):
4.BB.05Brunogeierite
(Ge,Fe)Fe
 
2
O
 
4
4.BB.05Chromite
FeCr
 
2
O
 
4
4.BB.05Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
4.BB.05Coulsonite
FeV
 
2
O
 
4
4.BB.05Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
4.BB.05Filipstadite
(Mn,Mg)
 
2
(Sb
 
.5
Fe
 
.5
)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
FeAl
 
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
MgCr
 
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.05Tegengrenite
(Mg,Mn
2+
 
)
 
2
Sb
5+
0.5
(Mn
3+
 
,Si,Ti)
 
0.5
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
 
2
O
 
3
4.BB.15Titanomaghemite
Fe
3+
 
(Fe
3+
 
,Ti
4+
 
,Fe
2+
 
,[])
 
2
O
 
4
Related Minerals - Hey's Index Grouping:
7.20.1Wüstite
FeO
7.20.3Maghemite
Fe
 
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
 
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
 
2
O
 
5
7.20.14Hercynite
FeAl
 
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
French names:
AimantFer oxydé magnétiqueFer oxydulé
German names:
EisenmohrEisenmulmEisenoxydoxydulFerroferritHammerschlag
MagneteisenerzMagneteisensteinMagnetischer EisensteinMagnetitMorpholit
SiegelsteinSyderit
Italian names:
Ferro magneticoFerro ossidolato
Latin names:
Magneti amicaMinera Ferri attractoriaMinera ferri nigricans
Russian names:
Магнетит
Spanish names:
FerroferritaHierro magnéticoMagnetitaMorpholitaSyderita
Swedish names:
MagnetjernmalmSvertmalm
Varieties:
Aluminous MagnetiteHydromagnetiteIshkuliteLodestoneManganmagnetite
Mg-TitanomagnetiteMushketoviteNickeloan MagnetiteSilfbergite (of Niggli)Titaniferous Magnetite
Vanado-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.

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