Walfordite

Walfordite

Walfordite from Tambo Mine, Elqui Province, Chile
General
Category Tellurite minerals
Formula
(repeating unit)
Fe3+,Te6+Te4+3O8
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 [1][2][3]

Walfordite is a rare tellurite mineral that was discovered in Chile in 1999.[4] The mineral is described as orange with orange-yellow streak, and is determined to have a chemical formula of Fe3+,Te6+Te4+3O8[1] with minor titanium and magnesium substitution resulting in an approximate empirical formula of (Fe3+,Te6+,Ti4+,Mg)(Te4+)3O8.[4]

Occurrence

The only reported occurrence[2] is in the Wendy open pit, El Indio-Tambo mining district of 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.[1]

References

  1. 1 2 3 Walfordite in the Handbook of Mineralogy
  2. 1 2 Walfordite on Mindat.org
  3. Walfordite data on Webmineral
  4. 1 2 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.
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