Europium(II) sulfate
Europium(II) sulfate is the inorganic compound with the formula EuSO4. Two polymorphs are known, α and the more stable β. Both are colorless. The β polymorph is isostructural with barium sulfate, hence it is insoluble in water. The salt is generated by addition of soluble europium(II) salts to dilute sulfuric acid. References

Europium(II) compounds
Sulfates