Walfordite
Walfordite is a very rare tellurite mineral that was discovered in Chile in 1999.[5] The mineral is described as orange with orange-yellow streak, and is determined to have a chemical formula of Fe3+,Te6+Te4+3O8[2] with minor titanium and magnesium substitution resulting in an approximate empirical formula of (Fe3+,Te6+,Ti4+,Mg)(Te4+)3O8.[5]
| Walfordite | |
|---|---|
 Walfordite from Tambo Mine, Elqui Province, Chile | |
| General | |
| Category | Tellurite minerals |
| Formula (repeating unit) | Fe3+,Te6+Te4+3O8 |
| IMA symbol | wfd[1] |
| Strunz classification | 4.JK.05 |
| Crystal system | Isometric |
| Space group | I2, Ia3 |
| Unit cell | a = 11.011 Å ; Z = 8 |
| Identification | |
| Colour | Orange |
| Crystal habit | Microscopic cubic crystals |
| Cleavage | None |
| Tenacity | Brittle |
| Luster | Adamantine |
| Streak | Orange-yellow |
| Diaphaneity | Opaque |
| Specific gravity | 5.841 (calculated) |
| Optical properties | Isotropic |
| Refractive index | n = 2.23 |
| References | [2][3][4] |
Occurrence
The only reported occurrence[3] is in the Wendy open pit, El Indio-Tambo mining district of the Coquimbo Region, northern Chile where it occurs in oxidized breccia associated with a tellurium-bearing gold deposit. Associated minerals include: alunite, rodalquilarite, native gold, emmonsite, jarosite and pyrite. The mineral was named for mine geologist Phillip Walford (1945— ) who first noted the mineral.[2]
See also
- El Indio Gold Belt. Tambo is adjacent to the El Indio mine. Both are now closed.
References
- 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.
- Walfordite in the Handbook of Mineralogy
- Walfordite on Mindat.org
- Walfordite data on Webmineral
- Back, Malcolm E.; Grice, Joel D.; Gault, Robert A.; Criddle, Alan J.; Mandarino, Joseph A. (1999). "Walfordite, a New Tellurite Species from the Wendy Open Pit, El Indio - Tambo Mining Property, Chile" (PDF). The Canadian Mineralogist. 37: 1261–1268.