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About WilcoxiteHide

MgAl(SO4)2F · 17H2O
Colourless, white
Vitreous, Greasy
1 - 2
Specific Gravity:
Crystal System:
Member of:
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).

Classification of WilcoxiteHide

Approval Year:
First Published:

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
E : With only medium-sized cations; unclassified

9 : (AB)(XO4)Zq·xH2O

26 : Sulphates with Halide

Physical Properties of WilcoxiteHide

Vitreous, Greasy
Transparent, Translucent
Colourless, white
1 - 2 on Mohs scale
1.58 g/cm3 (Measured)    1.67 g/cm3 (Calculated)
Measured using a 21.6 mg sample on the Berman balance (six trials in toluene).

Optical Data of WilcoxiteHide

Biaxial (-)
RI values:
nα = 1.424 nβ = 1.436 nγ = 1.438
Measured: 48° , Calculated: 44°
Max Birefringence:
δ = 0.014
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
not discernible

Chemical Properties of WilcoxiteHide

MgAl(SO4)2F · 17H2O

Crystallography of WilcoxiteHide

Crystal System:
Class (H-M):
1 - Pinacoidal
Space Group:
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)°
a:b:c = 0.984 : 1 : 2.207
Unit Cell V:
579.6 ų
{010}, {110}, {100}, {-110}, and {0-11}

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0019831WilcoxitePeterson R C, Joy B R (2013) Wilcoxite MgAl(SO4)2F*17H2O, from Rico, Colorado: occurrence and crystal structure The Canadian Mineralogist 51 107-1172013Rico, Colorado, USA0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
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 EnvironmentHide

Geological Setting:
In hydrothermal systems containing significant amounts of fluorine

Type Occurrence of WilcoxiteHide

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.
Associated Minerals at Type Locality:

Synonyms of WilcoxiteHide

Other Language Names for WilcoxiteHide


Relationship of Wilcoxite to other SpeciesHide

Member of:
Other Members of this group:
AubertiteCuAl(SO4)2Cl · 14H2OTric. 1
Magnesioaubertite(Mg,Cu)Al(SO4)2Cl · 14H2OTric. 1 : P1
Svyazhinite(Mg,Mn2+,Ca)(Al,Fe3+)(SO4)2F · 14H2OTric.

Related Minerals - Nickel-Strunz GroupingHide

7.DE.05MangazeiteAl2(SO4)(OH)4 · 3H2OTric.
7.DE.10CarbonatecyanotrichiteCu4Al2(CO3,SO4)(OH)12 · 2H2OOrth.
7.DE.10CyanotrichiteCu4Al2(SO4)(OH)12 · 2H2OMon. 2/m : B2/m
7.DE.10UKI-1975-(SO:AlCu)(Cu, Al, SO4, H2O)
7.DE.15SchwertmanniteFe3+16(OH,SO4)12-13O16 · 10-12H2OTet.
7.DE.20TlalociteCu10Zn6(Te6+O4)2(Te4+O3)(OH)25Cl · 27H2OOrth.
7.DE.25UtahiteMgCu4Zn2Te6+3O14(OH)4 · 6H2OTric.
7.DE.35CoquanditeSb6+xO8+x(SO4)(OH)x(H2O)1- x (x = 0.3)Tric. 1 : P1
7.DE.40OsakaiteZn4(SO4)(OH)6 · 5H2OTric. 1 : P1
7.DE.50Stanleyite(V4+O)(SO4) · 6H2OOrth.
7.DE.55McalpineiteCu3(Te6+O6)Iso. m3 (2/m 3) : Ia3
7.DE.60HydrobasaluminiteAl4(SO4)(OH)10 · 12-36H2OMon.
7.DE.62VolaschioiteFe4(SO4)O2(OH)6 · 2H2OMon. 2/m : B2/m
7.DE.65ZaheriteAl12(SO4)5(OH)26 · 20H2OTric.
7.DE.70LautenthalitePbCu4(SO4)2(OH)6 · 3H2OMon. 2/m : P21/b
7.DE.75CamérolaiteCu6Al3(OH)18(H2O)2[Sb(OH)6](SO4)Tric. 1 : P1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

26.2SulphohaliteNa6(SO4)2FClIso. m3m (4/m 3 2/m)
26.3SchaireriteNa21(SO4)7ClF6Trig. 3m (3 2/m)
26.5ConnelliteCu19(SO4)(OH)32Cl4 · 3H2OHex. 6 m2 : P62c
26.6ChlorothioniteK2Cu(SO4)Cl2Orth. mmm (2/m 2/m 2/m) : Pnma
26.7KamchatkiteKCu3(SO4)2OClOrth. mmm (2/m 2/m 2/m) : Pnma
26.8SpangoliteCu6Al(SO4)(OH)12Cl · 3H2OTrig. 3m : P3 1c
26.9AubertiteCuAl(SO4)2Cl · 14H2OTric. 1
26.10Magnesioaubertite(Mg,Cu)Al(SO4)2Cl · 14H2OTric. 1 : P1
26.11Svyazhinite(Mg,Mn2+,Ca)(Al,Fe3+)(SO4)2F · 14H2OTric.
26.14KainiteKMg(SO4)Cl · 3H2OMon. 2/m : B2/m
26.15Mosesite(Hg2N)(Cl,SO4,MoO4) · H2OIso. 4 3m : F4 3m
26.16Kleinite(Hg2N)(Cl,SO4) · nH2OHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
26.18CreediteCa3SO4Al2F8(OH)2 · 2H2OMon. 2/m : B2/b
26.19LannoniteMg2Ca4Al4(SO4)8F8 · 24H2O Tet. 4/m : I4/m
26.20Chukhrovite-(Y)Ca3(Y,Ce)(AlF6)2(SO4)F · 10H2OIso.
26.21Chukhrovite-(Ce)Ca3(Ce,Y)(AlF6)2(SO4)F · 10H2OIso.
26.22GrandreefitePb2(SO4)F2Mon. 2/m
26.23PseudograndreefitePb6(SO4)F10Orth. 2 2 2 : F2 2 2
26.26MammothitePb6Cu4AlSb5+O2(OH)16Cl4(SO4)2Mon. 2 : B2
26.27AtlasoviteK(BiO)Cu6Fe3+(SO4)5O3ClTet. 4/mmm (4/m 2/m 2/m) : P4/ncc
26.28XitieshaniteFe3+(SO4)Cl · 6H2OMon. 2/m : P21/b

Other InformationHide

Thermal Behaviour:
When heated slightly, mineral dissolves in its own water.
Easily dissolved by cold water and dilute acids.
Special Storage/
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.

References for WilcoxiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Williams, S.A., Cesbron, F.P. (1983) Wilcoxite and lannonite, two new fluosulfates from Catron County, New Mexico. Mineralogical Magazine: 47: 37-40.
Dunn, P.J., Cabri, L.J., Chao, G.Y., Fleischer, M., Francis, C.A., Grice, J.D., Jambor, J.L., Pabst, A. (1984) New mineral names. American Mineralogist: 69: 406-412.
Peterson, R.C., Joy, B.R. (2013) Wilcoxite MgAl(SO4)2F•17H2O, from Rico, Colorado: Occurrence and crystal structure. Canadian Mineralogist: 51: 107-117.

Internet Links for WilcoxiteHide

Localities for WilcoxiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • San Juan Province
    • Iglesia Department
Bengochea, L., Lara, R. y Mas, G., 1996. Kalinita y boyleita. Sulfatos secundarios del Área Valle del Cura; San Juan. 3ra Reunión de Mineralogía y Metalogenia. Instituto de Recursos Minerales, UNLP. Publicación 5: 63-66.
  • Thuringia
    • Ronneburg U deposit
T. Witzke & F. Rüger: Lapis 1998(7/8), 26-64
  • Nógrád County
collector: István Krisztián, XRD: Ferenc Kristály, EDS: Sándor Szakáll
  • Piedmont
    • Cuneo Province
      • Entracque
Ciriotti, M.E., Ferrero, S., Blass, G., and Ambrino, P. (2008) Wilcoxite: primo ritrovamento italiano. Micro (UK report), 2-2008, 75-76; Ciriotti, M.E., Cámara, F., Ferrero, S., Bracco, R., Marengo, A., and Bittarello, E. (2020) Matlockite, ramsdellite, tschermigite e un'interessante soluzione solida gadolinite-datolite Y-dominante: prime segnalazioni per la provincia di Cuneo e per il Piemonte. Micro, 18, 1-2002, 30-45.
  • Tuscany
    • Lucca Province
      • Vergemoli
Mauro, D. (2020). Crystal-chemistry of secondary minerals of thallium-rich pyrite from the Apuan Alps (Tuscany, Italy). Plinius, 46, 64-68.
Mauro D. (2016): Studio cristallochimico di alcuni solfati di ferro della mineralizzazione a pirite tallifera di Fornovolasco (Alpi Apuane). Tesi magistrale, Dipartimento di Scienze della Terra, Unviersità di Pisa, 137 pp.
  • Sakha Republic (Yakutia)
    • Verkhoyansk Fold Belt
      • Verkhoyansk Silver Province
        • Deputatsky ore cluster
Zhdanov Yu.Ya., Solov’yev L.I. and Suknev V.S. (1993) Wilcoxite from Yakutia, its second find in the world, - Doklady Rus. Ac. Nauk, 317, p. 136–139 (in Rus.).; Zhdanov Yu.Ya., Solov'ev L.I. (1998): Geology and mineralogical composition of the oxidized zone in the Deputatsk tin ore deposit. Otechestvennaya Geol. (6), 77-79 (in Russian).
South Africa
  • KwaZulu-Natal
    • uMzinyathi District Municipality
Bangert, B., & Von Brunn, V. (2001). Tuffaceous beds in glaciogenic argillites of the late Palaeozoic Dwyka Group of KwaZulu-Natal, South Africa. Journal of African Earth Sciences, 32(1), 133-140.
  • Valais
    • Martigny
      • Mont Chemin mining district
Stalder, H. A., Wagner, A., Graeser, S. und Stuker, P. (1998): Mineralienlexikon der Schweiz. Wepf Verlag, Basel, 579 pp.
  • Colorado
    • Dolores Co.
      • Rico Mountains
        • Rico Mining District (Pioneer Mining District)
Peterson, R. C. & Joy, B. R. (2013): Wilcoxite MgAl(SO4)2F•17H2O, from Rico, Colorado: Occurrence and crystal structure. Canadian Mineralogist 51, 107-117.
  • Michigan
    • Dickinson Co.
      • Randville
Mineralogy of Michigan (E. W. Heinrich & G. W. Robinson)
  • New Mexico
    • Catron Co.
      • Wilcox Mining District
        • Lone Pine Hill area
Williams, S. A. & Cesbron, F. P. (1983): Wilcoxite and lannonite, two new fluosulfates from Catron County, New Mexico. Mineralogical Magazine 47, 37-40; Northrop, Minerals of New Mexico, 3rd Rev. Ed., 1996
Mineral and/or Locality  
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