Copper Sulphate Crystal is often referred to as copper sulphate. It has the chemical formula CuSO4 and is an inorganic substance. CuSO4-nH2O hydrates are created. The most frequent hydrate of copper(II) sulphate is pentahydrate (n = 5), a vivid blue crystal. The pentahydrate is also known by the names blue vitriol, bluestone, the vitriol of copper, and Roman vitriol. Copper Sulphate Crystal dissolves exothermically in water to produce the aqua complex [Cu(H2O)6]. 2