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Magnetite

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Formula:
Fe2+Fe3+2O4
Colour:
Greyish black or iron black
Lustre:
Metallic, Sub-Metallic
Hardness:
5½ - 6½
Specific Gravity:
5.175
Crystal System:
Isometric
Member of:
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).

May precipitate from supersaturated volcanic gas due to its cooling as shown in an experiment by Africano et al. (2002) (actually a predominant precipitate from ca. 850 down to 650oC in this particular experiment).

Visit gemdat.org for gemological information about Magnetite.


Classification of Magnetite

Approved, 'Grandfathered' (first described prior to 1959)
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
7.2.2.3

7 : MULTIPLE OXIDES
2 : AB2X4
7.20.2

7 : Oxides and Hydroxides
20 : Oxides of Fe

Physical Properties of Magnetite

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

Optical Data of Magnetite

Type:
Isotropic
RI values:
n = 2.42
Max 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:
Fe2+Fe3+2O4
Common Impurities:
Mg,Zn,Mn,Ni,Cr,Ti,V,Al

Crystallography of Magnetite

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Cell Parameters:
a = 8.397 Å
Unit Cell 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}.

Crystallographic forms of Magnetite

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)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Epitaxial Relationships of Magnetite

Epitaxial Minerals:
RutileTiO2
RutileTiO2
PyrophaniteMn2+TiO3
Olivine(Mg,Fe2+)2SiO4
MuscoviteKAl2(AlSi3O10)(OH)2
IlmeniteFe2+TiO3
HematiteFe2O3
Epitaxy Comments:
Hematite overgrowths on, and inclusions in, magnetite; ilmenite inclusions, rutile overgrowths, chlorite group overgrowths, pyrophanite inclusions; magnetite on hematite; inclusions in muscovite; inclusions in hematite; inclusions in ilmenite; magnetite overgrowths on olivine

X-Ray Powder Diffraction

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
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.

Synonyms of Magnetite

Other Language Names for Magnetite

Varieties of Magnetite

Aluminous Magnetite

Al-rich variety of magnetite

Chrommagnetite

A member of Chromite-Magnetite Series - a chromian variety of Magnetite with Cr3+ contents 0,50-1 apfu.

Hydromagnetite

A hydrated Magnetite.

Ishkulite

A member of Chromite-Magnetite Series - a chromian variety of Magnetite with Cr3+ contents 0,10-0,50 apfu.

Lodestone

A variety of magnetite that is a natural magnet (magnetized).

Manganmagnetite

A variety of magnetite containing Mn 2+ substituting for Fe 2+.

Mg-Titanomagnetite

Titanium/Magnesium rich Magnetite

Mushketovite

The name given for Magnetite pseudomorphs after Hematite.

Nickeloan Magnetite
Silfbergite (of Niggli)

A manganoan variety of magnetite. Contains Mn 2+ substituting for Fe 2+.

Titaniferous Magnetite

A titanian variety of Magnetite.

Vanadian-Titanian Magnetite

May also be formulated as vanadiferous titanomagnetite.

Vanado-Magnetite

A vanadian variety of magnetite. V content reported up to 4.84% (India).

Relationship of Magnetite to other Species

Member of:
Other Members of this group:
ChromiteFe2+Cr3+2O4
Cochromite(Co,Ni,Fe)(Cr,Al)2O4
CoulsoniteFe2+V3+2O4
CuprospinelCu2+Fe3+2O4
Filipstadite(Sb0.5Fe0.5)Mn2O4
FrankliniteZn2+Fe3+2O4
GahniteZnAl2O4
GalaxiteMn2+Al2O4
HercyniteFe2+Al2O4
JacobsiteMn2+Fe3+2O4
MagnesiochromiteMgCr2O4
MagnesiocoulsoniteMgV2O4
MagnesioferriteMgFe3+2O4
ManganochromiteMn2+Cr2O4
Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
Qandilite(Mg,Fe3+)2(Ti,Fe3+,Al)O4
SpinelMgAl2O4
TrevoriteNi2+Fe3+2O4
UlvöspinelFe2TiO4
VuorelaineniteMn2+V3+2O4
XieiteFe2+Cr2O4
ZincochromiteZnCr2O4
Forms a series with:

Common Associates

Associated Minerals Based on Photo Data:
Calcite243 photos of Magnetite associated with Calcite on mindat.org.
Hematite196 photos of Magnetite associated with Hematite on mindat.org.
Quartz173 photos of Magnetite associated with Quartz on mindat.org.
Epidote150 photos of Magnetite associated with Epidote on mindat.org.
Chalcopyrite113 photos of Magnetite associated with Chalcopyrite on mindat.org.
Pyrite92 photos of Magnetite associated with Pyrite on mindat.org.
Feldspar Group88 photos of Magnetite associated with Feldspar Group on mindat.org.
Perovskite75 photos of Magnetite associated with Perovskite on mindat.org.
Clinochlore72 photos of Magnetite associated with Clinochlore on mindat.org.
Andradite64 photos of Magnetite associated with Andradite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

4.BB.05ChromiteFe2+Cr3+2O4
4.BB.05Cochromite(Co,Ni,Fe)(Cr,Al)2O4
4.BB.05CoulsoniteFe2+V3+2O4
4.BB.05CuprospinelCu2+Fe3+2O4
4.BB.05Filipstadite(Sb0.5Fe0.5)Mn2O4
4.BB.05FrankliniteZn2+Fe3+2O4
4.BB.05GahniteZnAl2O4
4.BB.05GalaxiteMn2+Al2O4
4.BB.05HercyniteFe2+Al2O4
4.BB.05JacobsiteMn2+Fe3+2O4
4.BB.05ManganochromiteMn2+Cr2O4
4.BB.05MagnesiocoulsoniteMgV2O4
4.BB.05MagnesiochromiteMgCr2O4
4.BB.05MagnesioferriteMgFe3+2O4
4.BB.05Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
4.BB.05Qandilite(Mg,Fe3+)2(Ti,Fe3+,Al)O4
4.BB.05SpinelMgAl2O4
4.BB.05TrevoriteNi2+Fe3+2O4
4.BB.05UlvöspinelFe2TiO4
4.BB.05VuorelaineniteMn2+V3+2O4
4.BB.05ZincochromiteZnCr2O4
4.BB.10HausmanniteMn2+Mn3+2O4
4.BB.10HetaeroliteZnMn2O4
4.BB.10HydrohetaeroliteZnMn2O4 · H2O
4.BB.10IwakiiteMn2+Fe3+2O4
4.BB.15MaghemiteFe3+2O3
4.BB.15TitanomaghemiteFe3+(Fe3+,Ti4+,Fe2+,◻)2O4
4.BB.20Tegengrenite(Mg,Mn2+)2Sb5+0.5(Mn3+,Si,Ti)0.5O4
4.BB.25XieiteFe2+Cr2O4

Related Minerals - Hey's Chemical Index of Minerals Grouping

7.20.1WüstiteFeO
7.20.3MaghemiteFe3+2O3
7.20.4HematiteFe2O3
7.20.5Goethiteα-Fe3+O(OH)
7.20.6Akaganeite(Fe3+,Ni2+)8(OH,O)16Cl1.25 · nH2O
7.20.7FeroxyhyteFe3+O(OH)
7.20.8Lepidocrociteγ-Fe3+O(OH)
7.20.9FerrihydriteFe3+10O14(OH)2
7.20.10Amakinite(Fe2+,Mg)(OH)2
7.20.11MagnesioferriteMgFe3+2O4
7.20.12MuskoxiteMg7Fe4O13 · 10H2O
7.20.13SrebrodolskiteCa2Fe3+2O5
7.20.14HercyniteFe2+Al2O4
7.20.15BrownmilleriteCa2(Al,Fe3+)2O5

Related Minerals - Dana Grouping (8th Ed.)

7.2.2.1MagnesioferriteMgFe3+2O4
7.2.2.2JacobsiteMn2+Fe3+2O4
7.2.2.4FrankliniteZn2+Fe3+2O4
7.2.2.5TrevoriteNi2+Fe3+2O4
7.2.2.6CuprospinelCu2+Fe3+2O4

Other Information

Magnetism:
Ferromagnetic
Health Risks:
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.

Magnetite in petrology

An essential component of (items highlighted in red)
Common component of (items highlighted in red)
Accessory component of (items highlighted in red)

References for Magnetite

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Mügge (1905) Jb. Min., Beil.-Bd.: 16: 335.
Bragg (1915) Nature: 95: 561.
Bragg (1915) Phl. Magazine: 30: 305.
Greig, Merwin, Posnjak (1936) American Mineralogist: 21: 504.
Palache, C., Berman, H., Frondel, C. (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., Lindsley, D.H. (1964) Iron-titanium oxide minerals and synthetic equivalents. Journal of Petrology: 5: 310-357.
Johnson, H.P., 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., Virgo, D., Bell, P.M. (1977) High-pressure 57Fe Mössbauer data on the phase and magnetic transitions of magnesioferrite (MgFe2O4), magnetite (Fe3O4), and hematite (Fe2O3). Carnegie Institution of Washington Year Book: 76: 522-525.
Cawthorn, R.G., 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., Barnett, R.L. (1980) Oriented magnetite inclusions in pyroxenes from the Grenville province. Canadian Mineralogist: 18: 89-99.
Fleet, M.E. (1982) 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., Reeder, R.J. (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., 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., Nasu, S., Wada, K., Endo, S. (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., 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., Parker, F.T. (1998) Magnetoresistance of magnetite. Applied Physics Letters: 72: 734-736.
Haavik, C., Stølen, S., Fjellvåg, H., Hanfland, M., D. Häusermann, D. (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., 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., Radaelli, P.G. (2001) Long range charge ordering in magnetite below the Verwey transition. Physical Review Letters: 27: 266401/1-4.
Cornell, R.M., 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., 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., Chen, C.T. (2004) Spin and orbital magnetic moments of Fe3O4. Physical Review Letters: 93: 077204/1-4.
Lazor, P., Shebanova, O.N., Annersten, H. (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., Vaughan, D.J. (2006) Direct determination 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: 1: 10-20.
Africano, F., Van Rompaey, G., Bernard, A., Le Guern, F. (2002): Deposition of trace elements from high temperature gases of Satsuma-Iwojima volcano. Earth Planets Space: 54: 275-286

Internet Links for Magnetite

mindat.org URL:
https://www.mindat.org/min-2538.html
Please feel free to link to this page.
Specimens:
The following Magnetite specimens are currently listed for sale on minfind.com.

Significant localities for Magnetite

Showing 15 significant localities out of 15,174 recorded on mindat.org.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Australia
 
  • Tasmania
    • Burnie City
      • Hampshire district
        • Kara Mines
Whitehead, 1990; Ralph Bottrill 6/10/2005.; MINERALOGICAL MAGAZINE, SEPTEMBER 1984, VOL. 48, PP. 397-400; Singoyi, B. (1995). Mineral paragenesis, geochemistry and fluid characteristics of the Kara scheelite-magnetite skarn deposit, Northwestern Tasmania (Masters dissertation, University of Tasmania).
Canada
 
  • Ontario
    • Hastings Co.
      • Faraday Township
Robinson & Chamberlain (1982) - Mineralogical Record v14 n2; Joyce, D. K. (2006) Calcite Vein-Dikes of the Grenville Geological Province, Ontario, Canada. Rocks and Minerals 81:34-42; Ontario Ministry of Northern Development and Mines,MDI Number: MDI31F04SW00297
  • Québec
    • Abitibi-Témiscamingue
      • La Vallée-de-l'Or RCM
        • Réservoir-Dozois
Olivier Langelier Collection; Hudon, P., Friedman, R.M., Gauthier, G. & Martignole, J. (2006) Age of the Cabonga nepheline syenite, Grenville Province, western Quebec. Canadian Journal of Earth Sciences, vol. 43(9), 1237-1249.
France
 
  • Brittany
    • Côtes-d'Armor
Pierrot R., Chauris L., Laforêt C. (1975), Inventaire minéralogique de la France, Ed. BRGM, n°5, Côtes du Nord, pp: 110-113
Portugal
 
  • Leiria District
    • Nazaré
      • Nazaré
Collected by Rui Nunes in several visits to the locality
UK
 
  • Scotland
    • Shetland Islands
      • Mainland
        • Fethaland Point
[Specimen in the Natural History Museum, London]
USA
 
  • Alaska
    • Prince of Wales-Outer Ketchikan Borough
      • Ketchikan District
        • Prince of Wales Island
Min Rec 35:5 pp383-404, 419-420
  • Connecticut
    • Middlesex Co.
      • Haddam
        • Higganum
Foye (1922); Rice and Foye (1927); Williams (circa 1945)
Schooner, Richard. (circa 1985), Untitled manuscript on central Connecticut mineralogy.
  • Massachusetts
    • Middlesex Co.
Dale, T. Nelson (1910). Supplementary Notes on the Commercial Granites of New England. (USGS Bulletin 470).
  • New York
    • Putnam Co.
      • Town of Southeast
        • Brewster
(Dana, 1874) (Januzzi, 1966, 1989) (Man¬chester, 1931) (Trainer, 1938, 1941) (Whitlock, 1903) (Nightingale 2001) Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 214..
  • Pennsylvania
    • Lebanon Co.
      • Cornwall Borough (Cornwall)
Rocks & Min.: 13:213.; Econ Geol (1985) 80:418-443
  • Rhode Island
    • Providence Co.
      • Providence
        • Manton
Miller, C. E. (1971) Rhode Island Minerals and Their Locations, University of Rhode Island, Kingston
  • Wisconsin
    • Dodge Co.
      • Iron Ridge District (Neda Iron District)
        • Iron Ridge Mines
Hawley, J. & A. Bevan (1934) Mineralogy and genesis of the Mayville iron ore of Wisconsin: american Mineralogist: 19 (11): 493- 514.
Hawley, J. & A. Bevan (1934) Mineralogy and genesis of the Mayville iron ore of Wisconsin: american Mineralogist: 19 (11): 493- 514.
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