Tripuhyite
From Wikipedia, the free encyclopedia
Tripuhyite is an iron antimonate mineral with composition FeSbO4.
| Tripuhyite | |
|---|---|
Tripuhyite from the Tafone Mine, Grosseto Province, Tuscany, Italy | |
| General | |
| Category | Antimonate mineral |
| Formula | FeSbO4 |
| IMA symbol | Tpy[1] |
| 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 | [2][3][4] |
Nomenclature
The name of the mineral comes from the locality of Tripuhy, Ouro Preto, Minas Gerais, Brazil, where it was discovered. Hussak and Prior[5] 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.[6] However, other studies had shown that the original tripuhyite was also FeSbO4.[7] 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.[8]
Crystal Structure
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.
