Copper Sulphate, Packaging Type : blue

Niche uses
Being a relatively benign and cheap reagent, copper(II) sulfate has attracted many niche applications over the centuries.
Copper(II) sulfate, also known as cupric sulfate, is the chemical compound with the chemical formula CuSO4. This salt exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a pale green or gray-white powder, whereas the pentahydrate (CuSO4@5H2O), the most commonly encountered salt, is bright blue. Copper sulfate exothermically dissolves in water to give the aquo complex [Cu(H2O)6]2+, which has octahedral molecular geometry and is paramagnetic. Other names for copper(II) sulfate are "blue vitriol" and "bluestone".