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CategoryUranyl neso- and polysilicates
(repeating unit)
Strunz classification9.AK.15
Crystal systemMonoclinic
Crystal classSphenoidal (2)
(same H-M symbol)
Space groupP21
Unit cella = 15.85 Å, b = 6.98 Å
c = 6.64 Å; β = 97.45°; Z = 2
Formula mass586.36 g/mol
ColorLight yellow, lemon-yellow, honey-yellow, straw-yellow, green-yellow
Crystal habitCrystals occur as stellate needle aggregates; as fibrous crusts, and massive
Cleavage{100} Perfect
Mohs scale hardness2.5
LusterVitreous to pearly; waxy or dull when massive
StreakYellowish white
DiaphaneityTranslucent to subtranslucent
Specific gravity3.81 - 3.90
Optical propertiesBiaxial (-)
Refractive indexnα = 1.643 nβ = 1.666 nγ = 1.669
Birefringenceδ = 0.026
PleochroismWeak; X = colorless; Y = pale canary-yellow; Z = canary-yellow
2V angle32° to 45°, measured
Ultraviolet fluorescenceWeak yellow-green under both short and long UV
Other characteristicsRadioactive.svg Radioactive

Uranophane (Ca(UO2)2(SiO3OH)2·5H2O), also known as uranotile, is a rare calcium uranium silicate hydrate mineral that forms from the oxidation of other uranium-bearing minerals. It has a yellow color and is radioactive.

Alice Mary Weeks, and Mary E. Thompson of the United States Geological Survey, identified uranophane in 1953.[4]

Classic samples have been produced at Madawaska Mine near Bancroft, Ontario.[5]


  1. ^ Handbook of Mineralogy
  2. ^ Uranophane on Mindat.org
  3. ^ Uranophane on Webmineral
  4. ^ Moore, James Gregory (1963). Geology of the Mount Pinchot Quadrangle, Southern Sierra Nevada, California. U.S. Government Printing Office.
  5. ^ McDougall, Raymond (2019-09-03). "Mineral Highlights from the Bancroft Area, Ontario, Canada". Rocks & Minerals. 94 (5): 408–419. doi:10.1080/00357529.2019.1619134. ISSN 0035-7529. S2CID 201298402.