Wilcoxite
A valid IMA mineral species
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About Wilcoxite
Formula:
MgAl(SO4)2F · 17H2O
Colour:
Colourless, white
Lustre:
Vitreous, Greasy
Hardness:
1 - 2
Specific Gravity:
1.58
Crystal System:
Triclinic
Member of:
Name:
Named after William Wilcox (? – 28 April 1880, ALma, New Mexico, USA), discoverer of the Wilcox district, New Mexico, USA in 1879.
Soluble in cold water. Will dissolve in its own crystal water if only slightly heated ("Crystals dissolve in their water of crystallisation, if they are illuminated with a hot or bright light source under the microscope.", Williams & Cesbron, 1983).
Unique Identifiers
Mindat ID:
4288
Long-form identifier:
mindat:1:1:4288:4
IMA Classification of Wilcoxite
Classification of Wilcoxite
7.DE.45
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
E : With only medium-sized cations; unclassified
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
E : With only medium-sized cations; unclassified
31.9.9.1
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
26.17
26 : Sulphates with Halide
26 : Sulphates with Halide
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Wcx | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Wilcoxite
Vitreous, Greasy
Transparency:
Transparent, Translucent
Colour:
Colourless, white
Hardness:
1 - 2 on Mohs scale
Fracture:
Conchoidal
Density:
1.58 g/cm3 (Measured) 1.67 g/cm3 (Calculated)
Comment:
Measured using a 21.6 mg sample on the Berman balance (six trials in toluene).
Optical Data of Wilcoxite
Type:
Biaxial (-)
RI values:
nα = 1.424 nβ = 1.436 nγ = 1.438
2V:
Measured: 48° , Calculated: 44°
Max. Birefringence:
δ = 0.014
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
Surface Relief:
Moderate
Dispersion:
not discernible
Chemistry of Wilcoxite
Mindat Formula:
MgAl(SO4)2F · 17H2O
Element Weights:
Crystallography of Wilcoxite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Setting:
P1
Cell Parameters:
a = 6.644(1) Å, b = 6.749(2) Å, c = 14.892(2) Å
α = 79.664(4)°, β = 80.113(4)°, γ = 62.487(3)°
α = 79.664(4)°, β = 80.113(4)°, γ = 62.487(3)°
Ratio:
a:b:c = 0.984 : 1 : 2.207
Unit Cell V:
579.6 ų
Morphology:
{010}, {110}, {100}, {-110}, and {0-11}
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0019831 | Wilcoxite | Peterson R C, Joy B R (2013) Wilcoxite MgAl(SO4)2F*17H2O, from Rico, Colorado: occurrence and crystal structure The Canadian Mineralogist 51 107-117 | 2013 | Rico, Colorado, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.980 Å | (40) |
| 3.384 Å | (50) |
| 4.117 Å | (40) |
| 4.371 Å | (60) |
| 4.908 Å | (100) |
| 5.654 Å | (90) |
| 5.877 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47b : [Sulfates and sulfites] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Geological Setting:
In hydrothermal systems containing significant amounts of fluorine
Type Occurrence of Wilcoxite
General Appearance of Type Material:
Spongey masses of perfect to somewhat rounded crystals.
Place of Conservation of Type Material:
Natural History Museum, Paris, France.
The Natural History Museum, London, England, 1980,545.
National Museum of Natural History, Washington, D.C., USA, 149525.
The Natural History Museum, London, England, 1980,545.
National Museum of Natural History, Washington, D.C., USA, 149525.
Associated Minerals at Type Locality:
Synonyms of Wilcoxite
Other Language Names for Wilcoxite
Relationship of Wilcoxite to other Species
Member of:
Other Members of Aubertite Group:
| Aubertite | CuAl(SO4)2Cl · 14H2O | Tric. 1 : P1 |
| Magnesioaubertite | (Mg,Cu)Al(SO4)2Cl · 14H2O | Tric. 1 : P1 |
| Svyazhinite | (Mg,Mn2+,Ca)(Al,Fe3+)(SO4)2F · 14H2O | Tric. |
Related Minerals - Strunz-mindat Grouping
| 7.DE. | Magnesioalterite | Mg2Fe3+4(SO4)4(C2O4)2(OH)4 · 17H2O |
| 7.DE. | Fabritzite | Zn9(SO4)2(OH)12Cl2 · 6H2O |
| 7.DE. | Cossaite | (Mg0.5,◻)Al6(SO4)6(HSO4)F6 · 36H2O |
| 7.DE. | Downsite | K2(MoO3)3(SO4) · 4H2O |
| 7.DE. | Liangjunite | K2(Mo2O5)(SO4)2 · 3H2O |
| 7.DE.05 | Mangazeite | Al2(SO4)(OH)4 · 3H2O |
| 7.DE.10 | UKI-1975-(SO:AlCu) | (Cu, Al, SO4, H2O) |
| 7.DE.10 | Carbonatecyanotrichite | Cu4Al2(CO3,SO4)(OH)12 · 2H2O |
| 7.DE.10 | Cyanotrichite | Cu4Al2(SO4)(OH)12 · 2H2O |
| 7.DE.15 | Schwertmannite | Fe3+16(OH,SO4)12-13O16 · 10-12H2O |
| 7.DE.20 | Tlalocite | Cu10Zn6(Te6+O4)2(Te4+O3)(OH)25Cl · 27H2O |
| 7.DE.25 | Utahite | MgCu4Zn2Te6+3O14(OH)4 · 6H2O |
| 7.DE.35 | Coquandite | Sb6+xO8+x(SO4)(OH)x(H2O)1- x (x = 0.3) |
| 7.DE.40 | Osakaite | Zn4(SO4)(OH)6 · 5H2O |
| 7.DE.42 | Alterite | Zn2Fe3+4(SO4)4(C2O4)2(OH)4 · 17H2O |
| 7.DE.45 | Barrotite | Cu9Al(HSiO4)2[(SO4)(HAsO4)0.5](OH)12 · 8H2O |
| 7.DE.47 | Tiberiobardiite | {Cu9Al[SiO3(OH)]2(OH)12(H2O)6}(SO4)1.5 · 10H2O |
| 7.DE.50 | Bouškaite | (MoO2)2O(SO3OH)2(H2O)4 |
| 7.DE.50 | Stanleyite | (V4+O)(SO4) · 6H2O |
| 7.DE.57 | Khangalasite | Fe(SO4)(OH) · 2H2O |
| 7.DE.60 | Hydrobasaluminite | Al4(SO4)(OH)10 · 12-36H2O |
| 7.DE.62 | Volaschioite | Fe4(SO4)O2(OH)6 · 2H2O |
| 7.DE.65 | Zaherite | Al12(SO4)5(OH)26 · 20H2O |
| 7.DE.75 | Camérolaite | Cu6Al3(OH)18(H2O)2[Sb(OH)6](SO4) |
Other Information
Thermal Behaviour:
When heated slightly, mineral dissolves in its own water. Heated in a closed tube, produces water and HF.
Notes:
Easily dissolved by cold water and dilute acids.
Special Storage/
Display Requirements:
Display Requirements:
Must be kept dry and away from hot lighting.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Wilcoxite
mindat.org URL:
https://www.mindat.org/min-4288.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Wilcoxite
Localities for Wilcoxite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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.
Argentina | |
| Bengochea +1 other reference |
Germany | |
| Witzke et al. (1998) |
Hungary | |
| collector: István Krisztián |
Italy | |
| Ciriotti et al. (2008) +1 other reference |
| Mauro (2020) |
| Mauro D. (2016) +1 other reference | |
Russia | |
| Zhdanov Yu.Ya. (1993) +1 other reference |
South Africa | |
| Bangert et al. (2001) |
Switzerland | |
| Stalder et al. (1998) |
USA | |
| Peterson et al. (2013) |
| Heinrich et al. (2004) |
| Williams et al. (1983) +1 other reference |
| PXRD and EDS by Tony Kampf in May |
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Punta Chistafort, Entracque, Cuneo Province, Piedmont, Italy