Uranopilit in der Mineraliensammlung im Naturkundemuseum Berlin — Photo: Weirdmeister · CC BY-SA 4.0
Uranopilite
A hydrated uranyl sulfate-hydroxide — fluorescent, radioactive, a minor uranium ore.
Intro adapted from Wikipedia (CC BY-SA).
Uranopilite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (UO₂)₆(SO₄)O₂(OH)₆·14H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: specific gravity 3.7–4; Silky luster; optically biaxial.
IMA symbol Up, grandfathered status — known before the IMA’s founding, named in 1882.
A locally abundant secondary mineral formed under acid conditions by the oxidation of sulfides in the presence of uraninite; may be of post-mining origin.
It is found associated with Uraninite, zippeite, johannite, uranophane, soddyite, fourmarierite, gypsum.
The name comes from its content of URANium and the Greek for felt, for its texture.