Uranyl sulfate

Uranyl sulfate describes a family of inorganic compounds with the formula UO2SO4(H2O)n. These salts consist of sulfate, the uranyl ion, and water. They are lemon-yellow solids. Uranyl sulfates are intermediates in some extraction methods used for uranium ores.
Structure.
The structure of UO2(SO4)(H2O)3.5 is illustrative of the uranyl sulfates. The "trans"-UO22+ centers are encased in a pentagonal bipyramidal coordination sphere. In the pentagonal plane are five oxygen ligands derived from sulfate and aquo ligands. The compound is a coordination polymer. 
Uses.
Aside from the large scale use in mining, uranyl sulfate finds some use as a negative stain in microscopy and tracer in biology. The Aqueous Homogeneous Reactor experiment, constructed in 1951, circulated a fuel composed of 565 grams of U-235 enriched to 14.7% in the form of uranyl sulfate.
The acid process of milling uranium ores involves precipitating uranyl sulfate from the pregnant leaching solution to produce the semi-refined product referred to as yellowcake.