Wikipedia
Nickel(II) sulfate
Nickel(II) sulfate, or just nickel sulfate, usually refers to the inorganic compound with the formula NiSO(HO). This highly soluble blue-coloured salt is a common source of the Ni ion for electroplating.
Approximately 40,000 tonnes were produced in 2005. It is mainly used for electroplating of nickel.
In 2005–06, nickel sulfate was the top allergen in patch tests (19.0%).