• 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.
URANOPILITE specimens:
(hover for more info)
URANOPILITE specimen urp-1
$ 28.00
Dims: 3.4" x 2.7" x 1.5" (8.6 x 6.9 x 3.8 cm)
Wt: 5.83 oz. (165.5 g)
Mi Vida Mine, San Juan County, Utah, U.S.A.
Upon first glance, this specimen appears to be a chunk of nondescript brown quartzite rock with a few tiny traces of yellow coloring here and there. However, when one bathes it in shortwave UV light, one can easily see that a substantial portion of its surface area is covered with a thin layer of Uranopilite, a uranium sulfate mineral. Under UV, this thin layer glows a bright blue-green (it appears blue in the image). Close examination under normal light will show a slight yellow discoloration where the mineral coats the host. It is rather nondescript, as it shows no crystal form whatsoever and has a very dull luster. This is one of the best examples of a fluorescent mineral that I have seen, as the material is practically invisible under white light.
no photo
urp-1 ($ 28.00)
Mi Vida Mine, San Juan County, Utah, U.S.A.


Copyright ©1995-2023 by Amethyst Galleries, Inc.