Magnetite

This article is about the mineral magnetite as found in natural deposits. For other uses, see Iron(II,III) oxide.
Not to be confused with magnesite or manganite.
Magnetite
Magnetite from Bolivia
General
Category
Formula
(repeating unit)		iron(II,III) oxide, Fe2+Fe3+2O4
IMA symbolMag[1]
Strunz classification4.BB.05
Crystal systemIsometric
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFd3m (no. 227)
Unit cella = 8.397 Å; Z = 8
Identification
ColorBlack, gray with brownish tint in reflected sun
Crystal habitOctahedral, fine granular to massive
TwinningOn {Ill} as both twin and composition plane, the spinel law, as contact twins
CleavageIndistinct, parting on {Ill}, very good
FractureUneven
TenacityBrittle
Mohs scale hardness5.5–6.5
LusterMetallic
StreakBlack
DiaphaneityOpaque
Specific gravity5.17–5.18
SolubilityDissolves slowly in hydrochloric acid
References[2][3][4][5]
Major varieties
LodestoneMagnetic with definite north and south poles
Magnetite is one of the very few minerals that is ferrimagnetic; it is attracted by a magnet as shown here
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 mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic;[6] it is attracted to a magnet and can be magnetized to become a permanent magnet itself.[7][8] With the exception of extremely rare native iron deposits, it is the most magnetic of all the naturally occurring minerals on Earth.[7][9] Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism.[10]

Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak.[7] Small grains of magnetite are very common in igneous and metamorphic rocks.[11]

The chemical IUPAC name is iron(II,III) oxide and the common chemical name is ferrous-ferric oxide.[12]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W. "Magnetite" (PDF). Handbook of Mineralogy. Chantilly, VA: Mineralogical Society of America. p. 333. Retrieved 15 November 2018.
  3. ^ "Magnetite". mindat.org and the Hudson Institute of Mineralogy. Retrieved 15 November 2018.
  4. ^ Barthelmy, Dave. "Magnetite Mineral Data". Mineralogy Database. webmineral.com. Retrieved 15 November 2018.
  5. ^ Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20th ed.). Wiley. ISBN 978-0-471-80580-9.
  6. ^ Jacobsen, S.D.; Reichmann, H.J.; Kantor, A.; Spetzler, H.A. (2005). "A gigahertz ultrasonic interferometer for the diamond anvil cell and high-pressure elasticity of some iron-oxide minerals". In Chen, J.; Duffy, T.S.; Dobrzhinetskaya, L.F.; Wang, Y.; Shen, G. (eds.). Advances in High-Pressure Technology for Geophysical Applications. Elsevier Science. pp. 25–48. doi:10.1016/B978-044451979-5.50004-1. ISBN 978-0-444-51979-5.
  7. ^ a b c Hurlbut, Cornelius Searle; W. Edwin Sharp; Edward Salisbury Dana (1998). Dana's minerals and how to study them. John Wiley and Sons. pp. 96. ISBN 978-0-471-15677-2.
  8. ^ Wasilewski, Peter; Günther Kletetschka (1999). "Lodestone: Nature's only permanent magnet - What it is and how it gets charged". Geophysical Research Letters. 26 (15): 2275–78. Bibcode:1999GeoRL..26.2275W. doi:10.1029/1999GL900496. S2CID 128699936.
  9. ^ Harrison, R. J.; Dunin-Borkowski, RE; Putnis, A (2002). "Direct imaging of nanoscale magnetic interactions in minerals". Proceedings of the National Academy of Sciences. 99 (26): 16556–16561. Bibcode:2002PNAS...9916556H. doi:10.1073/pnas.262514499. PMC 139182. PMID 12482930.
  10. ^ Du Trémolet de Lacheisserie, Étienne; Damien Gignoux; Michel Schlenker (2005). Magnetism: Fundamentals. Springer. pp. 3–6. ISBN 0-387-22967-1.
  11. ^ Nesse, William D. (2000). Introduction to mineralogy. New York: Oxford University Press. p. 361. ISBN 9780195106916.
  12. ^ Morel, Mauricio; Martínez, Francisco; Mosquera, Edgar (October 2013). "Synthesis and characterization of magnetite nanoparticles from mineral magnetite". Journal of Magnetism and Magnetic Materials. 343: 76–81. Bibcode:2013JMMM..343...76M. doi:10.1016/j.jmmm.2013.04.075.