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Hausmannite

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Hausmannite
General
CategoryOxide mineral
Formula
(repeating unit)
MnIIMnIII2O4,
MnO·Mn2O3, or
Mn3O4
IMA symbolHsm[1]
Strunz classification4.BB.10
Crystal systemTetragonal
Crystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space groupI41/amd
Unit cella = 5.76 Å
c = 9.46 Å; Z = 4
Identification
Formula mass228.81 g/mol
ColorBrownish black, grayish.
Crystal habitMassive – granular – common texture observed in granite and other igneous rock. pseudo octahedral – crystals show an octahedral outline.
TwinningRepeated twins on {112}
Cleavage[001] Perfect
FractureUneven – flat surfaces (not cleavage) fractured in an uneven pattern.
TenacityBrittle
Mohs scale hardness5.5
LusterSubmetallic
StreakDark reddish brown
DiaphaneityOpaque, transparent on thin edges
Specific gravity4.7 – 4.84, average = 4.76
Optical propertiesUniaxial (−)
Refractive indexnε = 2.15, nω = 2.46
Birefringenceδ = 0.31
Other characteristicsAnisotropism: Distinct, bireflectance: weak; O = light gray; E = dark gray.
References[2][3][4]

Hausmannite is a complex oxide, or a mixed oxide, of manganese containing both di- and tri-valent manganese. Its chemical formula can be represented as MnIIMnIII2O4, or more simply noted as MnO·Mn2O3, or Mn3O4, as commonly done for magnetite (Fe3O4), the corresponding iron oxide. It belongs to the spinel group and forms tetragonal crystals. Hausmannite is a brown to black metallic mineral with Mohs hardness of 5.5 and a specific gravity of 4.8.

The type locality is Oehrenstock (Öhrenstock), Ilmenau, Thuringian Forest, Thuringia, Germany, where it was first described in 1813.[3] Locations include Batesville, Arkansas, US; Ilfeld, Germany; Langban, Sweden; and the Ural Mountains, Russia.[2] High quality samples have been found in South Africa and Namibia where it is associated with other manganese oxides, pyrolusite and psilomelane and the iron-manganese mineral bixbyite. Wilhelm Haidinger (1827) named it in honour of Johann Friedrich Ludwig Hausmann (1782–1859), Professor of Mineralogy, University of Göttingen, Germany.[3]

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References

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  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. ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Hausmannite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 2 July 2022.
  3. ^ a b c Hausmannite, Mindat.org, retrieved 2 July 2022
  4. ^ Barthelmy, David (2014). "Hausmannite Mineral Data". Webmineral.com. Retrieved 2 July 2022.