Hydrated uranyl sulfate, forming yellow, fluorescent, velvety crusts. It's a radioactive mineral associated with transformation.
Yellow, Greenish-Yellow, Lemon-Yellow, often forms velvety crusts or efflorescences, fluoresces green
Uranopilite is classified as a sulfate minerals mineral which typically crystallizes in the triclinic system. Its chemical formula is (UO2)6SO4(OH)6O2·14H2O.