Weeksite

Mineral
(repeating unit)K2(UO2)2Si6O15·4(H2O)IMA symbolWks[1]Strunz classification9.AK.30Crystal systemOrthorhombicCrystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)Space groupPnnb (no. 52)Unit cella = 14.26 Å, b = 35.88 Å
c = 14.2 Å; Z = 16IdentificationColourYellowCrystal habitOccurs as acicular to elongated bladed crystals, flattened on {010}, also as radiating fibrous clusters and spherulites, pseudotetragonalCleavageDistinct prismaticMohs scale hardness1–2LustreWaxy to silkyStreakYellowDiaphaneityTransparent to translucentSpecific gravity4.1Optical propertiesBiaxial (−)Refractive indexnα = 1.596 nβ = 1.603 nγ = 1.606Birefringenceδ = 0.010PleochroismX = colorless; Y = pale yellow-green; Z = yellow-green2V angleMeasured: 60°Other characteristics Radioactive greater than 70 Bq/gReferences[2][3][4]

Weeksite is a naturally occurring uranium silicate mineral with the chemical formula: K2(UO2)2Si6O15•4(H2O), potassium uranyl silicate. Weeksite has a Mohs hardness of 1–2. It was named for USGS mineralogist Alice Mary Dowse Weeks (1909–1988).[3][4]

Appearance

Weeksite is visually similar to other uranium minerals such as carnotite and zippeite, both being encrustations that form on other rocks (usually sandstones or limestones).

Occurrence

Weeksite was first described in 1960 for an occurrence on Topaz Mountain, Thomas Range, Juab County, Utah.[2]

Weeksite occurs within small "opal" veins within rhyolite and agglomerates, and as encrustations in sandstones and limestones. It occurs associated with opal, chalcedony, calcite, gypsum, fluorite, uraninite, thorogummite, uranophane, boltwoodite, carnotite and margaritasite.[3]

See also

  • Minerals portal

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b "Weeksite mineral information and data". Mindat.org. 2011-06-19. Retrieved 2012-02-10.
  3. ^ a b c Handbook of Mineralogy
  4. ^ a b Webmineral data for weeksite
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