What is Uranopilite?
Uranopilite is a soft hydrated uranyl sulfate that forms yellow fibrous crusts in the oxidised zones of uranium deposits.
Mineralogy and structure
Reference formula: (UO2)6(SO4)O2(OH)6·14H2O. Uranopilite is a hydrated secondary uranium sulfate. Its exact COD 9004637 model is used for the structure page, while natural hydration and alteration can vary. Radioactivity is part of the specimen's handling profile. Uranopilite is classified with sulfates and has monoclinic crystal symmetry. Typical hardness is 2–3 on the Mohs scale and specific gravity is approximately 2.3–2.6.
Colour, lustre and habit
Typical colours include yellow, lemon-yellow, greenish-yellow. The usual fibrous, crusty, radiating habit and silky, pearly, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Uranopilite forms in or is associated with highly oxidised uranium mine workings, fractures, mine dumps and sulfate-rich alteration zones. Important documented localities include the Czech Republic, Germany, France, the United States, the United Kingdom and Australia.
A lemon-yellow sulfate crust from a mine
Uranopilite is a vivid indicator of aggressive oxidation and sulfate-rich mine chemistry. The fine crust is attractive in a cabinet but should be treated as a controlled scientific specimen.
Collecting and care
Radioactive and delicate: store enclosed and dry, avoid dust and water, and follow radiation-safety procedures for display, transport and study.
