• Chemistry: (UO2)6SO4(OH)10 - 12H2O , Hydrated Uranyl Sulfate Hydroxide.
  • Class: Sulfates
  • Uses: a minor ore of uranium and mineral specimens
  • Specimens

Uranopilite is a rare mineral but is sought after by collectors who seek uranium bearing minerals. As with many uranyl minerals, it is fluorescent and radioactive. Uranopilite fluoresces a bright green under ultraviolet light. Uranopilite is associated with other uranyl minerals such as zippeite and johannite. Uranopilite, johannite and zippeite all form as secondary minerals and as efflorescent crusts in uranium mines. Efflorescent means it forms on the surface of a rock by the evaporation of water when in contact with the dry air of the mine.

Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should be limited.


  • Colors are bright shades of yellow.
  • Luster is silky.
  • Transparency crystals can be transparent to translucent.
  • Crystal System is monoclinic.
  • Crystal Habits are usually limited to encrustations and compact masses.
  • Cleavage is not seen.
  • Hardness is approximately 2.
  • Specific Gravity is approximately 4.0 (above average for non-metallic minerals).
  • Streak is a pale yellow.
  • Other Characteristics: Radioactive and fluoresces a bright green under ultraviolet light.
  • Associated Minerals are uraninite, zippeite and johannite.
  • Notable Occurrences include Wheal Owles, Cornwall, England; San Juan Co., Utah, USA; Northwest Territory, Canada and the Bohemian region of Europe.
  • Best Field Indicators are color, crystal habit, fluorescence, softness, luster and radioactivity.
This Site Awarded
Available URANOPILITE specimens:
see this List of ALL specimens including SOLD ones


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