Tripuhyite

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Tripuhyite
General
Category Antimonate mineral
Formula
(repeating unit)
FeSbO4
Strunz classification 4.DB.05
Crystal system Tetragonal
Crystal class Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space group P41/mnm
Unit cell a = 4.63, c = 9.14 [Å]; Z = 2
Identification
Color Yellowish brown, lemon-yellow, brown-black
Crystal habit Fibrous to fine-grained aggregates
Mohs scale hardness 6 - 7
Luster Dull to earthy
Streak Canary-yellow to dark brown with a greenish tinge
Diaphaneity Translucent
Specific gravity 5.82
Optical properties Uniaxial (+)
Refractive index nω = 2.190 nε = 2.330
Birefringence δ = 0.140
Other characteristics Antiferromagnetic
References [1][2][3]

Tripuhyite is an iron antimonate mineral with composition FeSbO4.

Nomenclature[edit]

The name of the mineral comes from the locality of Tripuhy, Ouro Preto, Minas Gerais, Brazil, where it was discovered. Hussak and Prior[4] first described the mineral tripuhyite as an oxide of iron and antimony, and assigned it the composition Fe2Sb2O7. When a mineral with composition FeSbO4 was later discovered in Squaw Creek, New Mexico (US), it was considered erroneously as a new mineral and it was given the name squawcreekite.[5] However, other studies had shown that the original tripuhyite was also FeSbO4.[6] In 2002, the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), approved the redefinition of tripuhyite as FeSbO4 and the discreditation of squawcreekite.[7]

Crystal Structure[edit]

FeSbO4 exhibits the rutile structure, with a tetragonal unit cell. The cations are octahedrally coordinated to oxygen anions, with the octahedra sharing edges along the c-direction. Fe(III) and Sb(V) cations are distributed in a disordered way over the octahedral sites.

References[edit]

  1. ^ Mindat.org
  2. ^ Handbook of Mineralogy
  3. ^ Webmineral data
  4. ^ Hussak, E.; Prior, G. T. (1897). "On Tripuhyite, a New Antimonate of Iron, from Tripuhy, Brazil". Mineralogical Magazine. 11: 302–303. doi:10.1180/minmag.1897.011.53.04. 
  5. ^ Foord, E. E.; P. F. Hlava; J. J. Fitzpatrick; R. C. Erd; R. W. Hinton (1991). Neues Jahrbuch Fur Mineralogie-Monatshefte. 8: 363–384.  Missing or empty |title= (help)
  6. ^ Tavora, E. (1955). "X-ray diffraction powder data for some minerals from Brazilian localities". Anais da Academia Brasileira de Ciencias. 27: 7–27. 
  7. ^ Berlepsch, P.; T. Armbruster; J. Brugger; A. J. Criddle; S. Graeser (2003). "Tripuhyite, FeSbO4, revisited.". Mineralogical Magazine. 67: 31–46. doi:10.1180/0026461036710082.