Iron(III) sulfate
Iron(III) sulfate (or ferric sulfate), is a family of inorganic compounds with the formula Fe(SO)(HO). A variety of hydrates are known, in fact are the most commonly encountered form of "ferric sulfate". Solutions are used in dyeing as a mordant, and as a coagulant for industrial wastes. It is also used in pickling baths for aluminum and steel. Production. Generally, ferric sulfate is used as a solution generated from iron wastes. The actual speciation is vague but its applications do not demand high purity materials. As such iron(III) sulfate is generated and handled as an aqueous solution. It  is produced on a large scale by treating sulfuric acid, a hot solution of ferrous sulfate, and an oxidizing agent. Typical oxidizing agents include chlorine, nitric acid, and hydrogen peroxide. Natural occurrences. Iron sulfates occur as a variety of rare and commercially unimportant minerals. Mikasaite, a mixed iron-aluminium sulfate of chemical formula (Fe, Al)(SO) is the name of mineralogical form of iron(III) sulfate. This anhydrous form occurs very rarely and is connected with coal fires. The hydrates are more common, with coquimbite (nonahydrate) as probably the most often met among them. Paracoquimbite is the other, rarely encountered natural nonahydrate . Kornelite (heptahydrate) and quenstedtite (decahydrate) are rarely found. Lausenite (hexa- or pentahydrate) is a doubtful species. All the mentioned natural hydrates are unstable connected with the weathering (aerobic oxidation) of Fe-bearing primary minerals (mainly pyrite and marcasite).