Tripuhyite

 Tripuhyite is an iron antimonate mineral with composition FeSbO₄.

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 (+), canary-yellow color (transmitted light)
Refractive index	nω = 2.190 nε = 2.330
Birefringence	δ = 0.140
Pleochroism	None
Solubility	Insoluble in acids
Other characteristics	Antiferromagnetic
References	[1][2][3]

NomenclatureEdit

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 StructureEdit

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.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.