Zippeite

Zippeite is a hydrous potassium uranium sulfate mineral with formula: K₄(UO₂)₆(SO₄)₃(OH)₁₀·4(H₂O). It forms yellow to reddish brown monoclinic-prismatic crystals with perfect cleavage. The typical form is as encrustations and pulverulent earthy masses. It forms as efflorescent encrustations in underground uranium mines. It has a Mohs hardness of 2 and a specific gravity of 3.66. It is strongly fluorescent yellow in UV radiation and is a radioactive mineral.