ferric sulfate or iron (III) sulfate, chemical compound, Fe2(SO4)3, a yellow rhombic crystalline hygroscopic water-soluble salt that decomposes when heated to a temperature of 480°C. The enneahydrate, Fe2(SO4)3·9H2O, is a deliquescent rhombic crystalline salt that occurs in nature as the mineral coquimbite. It is used as a mordant in dyeing, as a coagulant for industrial wastes, in pickling baths for aluminum and steel, and in pigments.
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