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K2(UO2)2(Si5O13) · 4H2O
Waxy, Silky
1 - 2
Named in 1960 by W. F. Osterbridge, Mortimer Hay Staatz, Robert Meyrowitz, and A. M. Plummer in honor of Alice Mary Dowse Weeks [August, 26, 1909 Sherborn, Massachusetts, USA - August 29, 1988 Bryn Mawr, Pennsylvania, USA], mineralogist for the United States Geological Survey and later professor of mineralogy, Temple University (Philadelphia, USA).
This page provides mineralogical data about Weeksite.

Classification of Weeksite


9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates

53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)

14 : Silicates not Containing Aluminum
16 : Silicates of U

Physical Properties of Weeksite

Waxy, Silky
Hardness (Mohs):
1 - 2

Optical Data of Weeksite

Biaxial (-)
RI values:
nα = 1.596 nβ = 1.603 nγ = 1.606
Measured: 60° , Calculated: 66°
Max Birefringence:
δ = 0.010
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
r < v weak

Chemical Properties of Weeksite

K2(UO2)2(Si5O13) · 4H2O
Elements listed in formula:
Common Impurities:

Crystallography of Weeksite

Crystal System:
Cell Parameters:
a = 14.26 Å, b = 35.88 Å, c = 14.2 Å
a:b:c = 0.397 : 1 : 0.396
Unit Cell Volume:
V 7,265.41 ų (Calculated from Unit Cell)

Type Occurrence of Weeksite

Relationship of Weeksite to other Species

9.AK.05Soddyite(UO2)2SiO4 · 2H2O
9.AK.10CuprosklodowskiteCu(UO2)2(SiO3OH)2 · 6H2O
9.AK.10OursiniteCo(UO2)2(SiO3OH)2 · 6H2O
9.AK.10SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2O
9.AK.15Boltwoodite(K,Na)UO2(SiO3OH) · 1.5H2O
9.AK.15KasolitePb(UO2)SiO4 · H2O
9.AK.15NatroboltwooditeNa(UO2)(SiO3OH) · H2O
9.AK.15Uranophane-βCa(UO2)2(SiO3OH)2 · 5H2O
9.AK.15UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
9.AK.15Beta-UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
9.AK.20Swamboite-(Nd)U6+(UO2)6(SiO3OH)6 · 30H2O
9.AK.25HaiweeiteCa(UO2)2Si5O12(OH)2 · 6H2O
9.AK.25MetahaiweeiteCa(UO2)2Si6O15 · nH2O
9.AK.25RanquiliteCa(UO2)2[Si5O12(OH)2] · 6H2O
9.AK.30CoutinhoiteThxBa1-2x(UO2)2Si5O13 · 3H2O
9.AK.35UrsiliteMg4(UO2)4(Si2O5)5.5(OH)5 · 13H2O
9.AK.35MagnioursiliteMg4(UO2)4(Si2O5)5(OH)6 · 20H2O
9.AK.35CalcioursiliteCa4(UO2)4(Si2O5)5(OH)6 · 15H2O
14.16.3Soddyite(UO2)2SiO4 · 2H2O
14.16.4Swamboite-(Nd)U6+(UO2)6(SiO3OH)6 · 30H2O
14.16.6Boltwoodite(K,Na)UO2(SiO3OH) · 1.5H2O
14.16.7NatroboltwooditeNa(UO2)(SiO3OH) · H2O
14.16.8CuprosklodowskiteCu(UO2)2(SiO3OH)2 · 6H2O
14.16.9SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2O
14.16.10UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
14.16.11Uranophane-βCa(UO2)2(SiO3OH)2 · 5H2O
14.16.12HaiweeiteCa(UO2)2Si5O12(OH)2 · 6H2O
14.16.13MetahaiweeiteCa(UO2)2Si6O15 · nH2O
14.16.17KasolitePb(UO2)SiO4 · H2O
14.16.18OrlitePb3(UO2)3(Si2O7)2 · 6H2O
14.16.19OursiniteCo(UO2)2(SiO3OH)2 · 6H2O

Other Names for Weeksite

Name in Other Languages:

Other Information

Health Risks:
Contains uranium. Always wash hands after handling. Do not lick or ingest. Store in an uninhabited area

References for Weeksite

Reference List:
Outerbridge W.F., Staatz, M. H., Meyrowitz, R. & Pommer, A. M. (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab Co., UT, American Mineralogist: 45: 39-52.

Doklady Akademii Nauk SSSR: 282(5): 1132-1136.

Jackson, J.M. and Burns, P.C. (2001) A re-evaluation of the structure of weeksite, a uranyl silicate framework mineral. Canadian Mineralogist: 39: 187-195.

Burns, P.C. (2005) U 6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. Canadian Mineralogist: 43: 1839-1894.

K. Fejfarová, J. Plášil, H. Yang, J. Čejka, M. Dušek, R.T. Downs, M.C. Barkley, R. Škoda (2012): Revision of the crystal structure and chemical formula of weeksite, K2(UO2)2(Si5O13).4H2O. Am. Mineral. 97, 750-754.

Internet Links for Weeksite URL:
Please feel free to link to this page.

Localities for Weeksite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
  • South Australia
    • Flinders Ranges
      • North Flinders Ranges
        • Arkaroola Region (Arkaroola Station)
          • Mt Painter area
2003, Brugger, J., Ansermet, S. & Pring, A. ' Uranium minerals from Mt Painter, Northern Flinders ranges, South Australia' Australian Journal of Mineralogy, vol. 9, n°1, pp 15-31; Brugger, J., Meisser, N., Etschmann, B., Ansermet, S., & Pring, A. (2011). Paulscherrerite from the Number 2 Workings, Mount Painter Inlier, Northern Flinders Ranges, South Australia:“Dehydrated schoepite” is a mineral after all. American Mineralogist, 96(2-3), 229-240.
  • Carinthia
    • Millstatt lake ridge
      • Fresach
        • Laas
G. Niedermayr, I. Praetzel: Mineralien Kärntens, 1995
  • Minas Gerais
    • Galiléia
Bruno Gioia specimen; Atencio D, Carvalho F M S, Matioli P A (2004) Coutinhoite, a new thorium uranyl silicate hydrate, from Urucum Mine, Galiléia, Minas Gerais, Brazil. American Mineralogist 89, 721-724
  • São Paulo
    • São Paulo
Revista Brasileira de Geociências 24(1):43-51, March 1994; D Atencio & R Hypolito ()Fosfatos e silicatos secunderos de uranio de Perus, Sao Paulo
Fosfatos e Silicatos Secundários de Urânio de Perus, São Paulo - Atencio, Daniel and Hypolito, Raphael - Revista Brasileira de Geociências, março de 1994
  • Atacama Region
    • Copiapó Province
      • Zapallar district
        • Los Azules area
According to Dr. Tony Kampf, mineral has been confirmed by EDS and PXRD analysis
Czech Republic
  • Bohemia (Böhmen; Boehmen)
    • Karlovy Vary Region
      • Krušné Hory Mts (Erzgebirge)
        • Jáchymov District (St Joachimsthal)
Lapis 2002(7/8), 63-65
      • Mariánské Lázně (Marienbad)
Pauliš P., Kopecký S., Černý P. 2007: Uranové minerály České Republiky a jejich naleziště. 1. část. (Kutna Hora, issue 1)
    • Plzeň Region
      • Nepomuk (Pomuk)
Pauliš P., Kopecký S., Černý P. 2007: Uranové minerály České Republiky a jejich naleziště. 1. část. (Kutna Hora, issue 1)
  • Baden-Württemberg
    • Black Forest
      • Menzenschwand
Walenta: "Die Mineralien des Schwarzwaldes", Weise (Munich), 1992
  • Bavaria
    • Franconia
      • Spessart
        • Aschaffenburg
          • Dörrmorsbach
A. Wittern: "Mineralfundorte in Deutschland", Schweizerbart (Stuttgart), 2001
  • Honshu Island
    • Chugoku Region
      • Tottori Prefecture
K. Watanabe (1976) Journal of the Faculty of Science, Shinshu University, 11, 53-113 (in japanese with english summary)
  • Chihuahua
    • Mun. de Aldama
      • Peña Blanca District
        • Sierra Peña Blanca
Panczner(1987): 265 & 392.
Panczner(1987):265 & 392.
Panczner(1987):392.; Econ Geol (1991) 86:233-248; Wong, V., Goodell, P. C., & Anthony, E. Y. (1999, January). Characterization of U-series disequilibria at the Pena Blanca natural analogue site, Chihuahua, Mexico. In MRS Proceedings (Vol. 556, p. 801). Cambridge University Press.
  • Erongo Region
    • Swakopmund District
      • Goanikontes
Bezing, L. von, Bode, R. & Jahn, S. (2007): Namibia. Minerals and Localities. Edition Schloss Freudenstein, Bode Verlag, Haltern, 338 pp. (in English)
  • Puno Department
    • Carabaya Province
Geological Association of Canada (2014) Abstracts Fredericton Vol 37; Li, V. (2016). The Uranium Mineralization of the Macusani District, Southeast Peru: Mineralogy, Geochemistry, Geochronology and Ore-Genetic Model. PhD Thesis Queen’s University, Kingston, Ontario, Canada
  • Suceava Co.
    • Suceava district
Hîrtopanu P., Udubaşa G., Scott P., Hârtopanu I. (2004) Uranium sulphide mineralisation in the Bistriţa Mts., East Carpathians, Romania. Romanian Journal of Mineral Deposits 81:108-111
  • Arizona
    • Yavapai Co.
      • Date Creek Basin
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 155, 418.
      • Weaver Mts
        • Weaver District (Virginia District; Mocking Bird District)
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 418.
    • Yuma Co.
      • Muggins Mts
        • Muggins District
          • Muggins Mountains uranium prospects
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 127, 155, 411, 418; Outerbridge, W.F., et al (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab Co., UT, Am.Min.: 45: 39-52; Honea, R.M. (1959), New data on gastunite, an alkalin uranyl silicate, Am.Min.: 44: 1047-1056.
  • California
    • Inyo Co.
      • Coso Mts (Coso Range)
        • Coso District (New Coso District)
Outerbridge, W.F., et al (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab County, Utah, American Mineralogist (1960): 45: 39-52; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 517.
    • Lassen Co.
      • Mountain Meadow District
        • Round Mountain
American Mineralogist (1970): 45: 39-52.
  • Nevada
    • Humboldt Co.
      • Bottle Creek District
Nevada Bureau of Mines and Geology Online Documents OF06-19 - Nevada Uranium and Thorium Occurrences
      • Virgin Valley
NBMG files No. 50600003; Nevada Bureau of Mines and Geology NBMG Open-File Report 96-3 By Stephen B. Castor, Christopher D. Henry, Lisa A. Shevenell
NBMG Spec Pub 31 Minerals of Nevada
    • Mineral Co.
      • Marietta District
NBMG Spec Pub 31 Minerals of Nevada
    • Washoe Co.
      • Pyramid District
NBMG Spec Pub 31 Minerals of Nevada
  • New Mexico
    • Cibola Co.
Northrop, Minerals of New Mexico, 3rd. rev. ed. (1996)
Outerbridge, W.F., et al (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab County, Utah, Am.Min.: 45: 39-52;
    • McKinley Co.
Northrop, Minerals of New Mexico, 3rd Rev. Ed., 1996
  • Pennsylvania
    • Northampton Co.
      • Easton
        • Chestnut Hill (College Hill; Lafayette Hill; Mount Lafayette; Paxinosa Ridge)
          • C.K. Williams Quarry complex (Williams and Company Rock Quarry)
AmMin.45:39; Am Min. 66:610; Am.Min.: 45: 39-52
  • Texas
    • Live Oak Co.
U.S. Geological Survey,2005,Mineral Resources Data System :U.S. Geological Survey,Reston, Virginia
R&M 66:3 pp 196-224
    • Presidio Co.
Am.Min.: 45: 39-52
  • Utah
    • Grand Co.
      • Thompsons District (S. E. Thomsons)
        • Mollie Hogans
Van King
    • Juab Co.
      • Thomas Range
UGMS Bull 117 Minerals and Mineral Localities of Utah
UGMS Bull 117 Minerals and Mineral Localities of Utah
Outerbridge, W.F., et al (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab County, Utah, Am.Min.: 45: 39-52; Min.Rec.: 10: 271.
UGMS Bull 117 Minerals and Mineral Localities of Utah
    • San Juan Co.
      • White Canyon District
        • Red Canyon
Collection of Alex Earl
  • Wyoming
    • Niobrara Co.
      • Lusk
Outerbridge, W.F., et al (1960), Weeksite, a new uranium silicate from the Thomas Range, Juab County, Utah, Am.Min.: 45: 39-52;
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