Favreauite
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About Favreauite
Georges Favreau
Formula:
PbBiCu6O4(SeO3)4(OH) · H2O
Colour:
green
Lustre:
Vitreous
Hardness:
3
Specific Gravity:
4.851 (Calculated)
Crystal System:
Tetragonal
Name:
Named for Georges Favreau, amateur mineralogist and professional engineer, France, in recognition of his work on rare minerals and French mineral deposits; he was the President of the Association Française de Microminéralogie (1993-2007)
Type Locality:
Unique combination of elements. Also unique structure, although similar to that of nabokoite and atlasovite (all 3 species have structures derived from that of murdochite by selective deletion of atoms).
Structure details: (1) corrugated layer of CuO4 squares (2) SeO3 triangular pyramids decorating the squares; (3) O atoms in the sheet coordinated to 3 Cu atoms; (4) Pb, Bi, OH, and water in structural voids; (5) Cu has two additional long bonds to interlayer OH and water, thus forming Jahn-Teller elongated octahedra; (6) Bi resides in hollows in each Cu–O sheet; (7) Pb atoms connect successive sheets; (8) Bi and Pb are both in distorted cubic coordination; the Bi site has point symmetry 4; the Pb site has point symmetry 4.
Structure details: (1) corrugated layer of CuO4 squares (2) SeO3 triangular pyramids decorating the squares; (3) O atoms in the sheet coordinated to 3 Cu atoms; (4) Pb, Bi, OH, and water in structural voids; (5) Cu has two additional long bonds to interlayer OH and water, thus forming Jahn-Teller elongated octahedra; (6) Bi resides in hollows in each Cu–O sheet; (7) Pb atoms connect successive sheets; (8) Bi and Pb are both in distorted cubic coordination; the Bi site has point symmetry 4; the Pb site has point symmetry 4.
Classification of Favreauite
Approved
Approval Year:
2014
Physical Properties of Favreauite
Vitreous
Transparency:
Transparent
Comment:
calculated estimate for RI suggests at least subadamantine rather than vitreous
Colour:
green
Hardness:
3 on Mohs scale
Hardness Data:
Estimated
Cleavage:
Perfect
{001} basal cleavage
{001} basal cleavage
Fracture:
Irregular/Uneven
Density:
4.851 g/cm3 (Calculated)
Comment:
couldn't be measured
Optical Data of Favreauite
Type:
Uniaxial (-)
Pleochroism:
Visible
Comments:
shades of green (O < E)
Comments:
Mean RI calculated from Gladstone-Dale relationship = 1.854
Chemical Properties of Favreauite
Formula:
PbBiCu6O4(SeO3)4(OH) · H2O
Common Impurities:
Ca
Crystallography of Favreauite
Crystal System:
Tetragonal
Class (H-M):
4/m - Dipyramidal
Space Group:
P4/n
Cell Parameters:
a = 9.860(4) Å, c = 9.700(5) Å
Ratio:
a:c = 1 : 0.984
Unit Cell V:
943.03 ų (Calculated from Unit Cell)
Morphology:
Tabular crystals, flattened on {001}
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.67Å | (100) |
| 3.470Å | (76) |
| 3.190Å | (35) |
| 2.961Å | (40) |
| 2.831Å | (68) |
| 2.709Å | (33) |
| 2.632Å | (34) |
| 2.247Å | (36) |
Type Occurrence of Favreauite
General Appearance of Type Material:
tiny square tabular crystals, up to 0.1
× 0.01 mm, flattened on {001}, occurring in subparallel and divergent groups
× 0.01 mm, flattened on {001}, occurring in subparallel and divergent groups
Place of Conservation of Type Material:
Cotype material is deposited in the collections of the Museum Victoria, Australia, registration number M53004 and the Natural History Museum of Los Angeles County, Los Angeles, USA, catalogue numbers 64111, 64112, 64113
Geological Setting of Type Material:
vugs in a matrix; secondary mineral formed due to oxidation of the selenide vein within sandstones and shales
Associated Minerals at Type Locality:
Synonyms of Favreauite
Other Language Names for Favreauite
Common Associates
Associated Minerals Based on Photo Data:
| 1 photo of Favreauite associated with Schmiederite | Pb2Cu2(Se6+O4)(Se4+O3)(OH)4 |
Other Information
Notes:
Raman bands [cm-1]: 847 (ν1 SeO3 stretching); 764, 795 (ν3 SeO3 antisymmetric stetching), 493, 542 (ν2 SeO3 bending), 320, 392 (ν4 SeO3 bending); 3525b (O–H stretching)
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Favreauite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Mills, S.J. (2014): Un hommage à la contribution de Georges FAVREAU à la minéralogie: favreauite, un nouveau minéral de la mine El Dragón, Bolivie. Cahier des Micromonteurs 124, 36-39.
Mills, S.J., Kampf, A.R., Housley, R.M., Christy, A.G., Thorne, B., Chen, Y.-S. and Steele, I.M. (2014) Favreauite, IMA 2014-013. CNMNC Newsletter No. 20, June 2014, page 557; Mineralogical Magazine, 78, 549-558.
Mills, S.J., Kampf, A.R., Housley, R.M., Christy, A.G., Thorne, B., Chen, Y.-S. and Steele, I.M. (2014) Favreauite, a new selenite mineral from the El Dragón mine, Bolivia. European Journal of Mineralogy, 26, 771-781.
Internet Links for Favreauite
mindat.org URL:
https://www.mindat.org/min-45907.html
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Localities for Favreauite
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The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Bolivia (TL) | |
| Mills, S.J. (2014): Un hommage à la contribution de Georges FAVREAU à la minéralogie: favreauite, un nouveau minéral de la mine El Dragón, Bolivie. Cahier des Micromonteurs 124, 36-39.; Grundmann, G. and Förster H.-J. (2017) Origin of the El Dragón Selenium Mineralization, Quijarro Province, Potosí, Bolivia. Minerals, 7(5), 68; doi:10.3390/min7050068 |
El Dragón mine, Antonio Quijarro Province, Potosí, Bolivia