Polarised light micrograph of crystals of a mixture of manganese sulphate heptahydrate, ammonium nickel sulphate and copper chloride. Manganese sulphate is used to treat osteoporosis, anemia and premenstrual syndrome. copper (II) chloride is used as a catalyst for organic and inorganic reactions, a mordant for dyeing and printing textiles, a pigment for glass and ceramics, wood preservative, disinfectant, insecticide, fungicide, and herbicide, and as a catalyst in the production of chlorine from hydrogen chloride. The addition of ammonium sulfate to nickel sulfate precipitates a blue coloured solid analogous to Mohr's salt Fe(NH4)2(SO4)2 6H2O.