Ferric alum, also known as iron(III) ammonium sulfate, is a compound with the chemical formula FeNH₄(SO₄)₂·12H₂O. It typically appears as large lumps or crystals and is soluble in water. Ferric alum is widely used in water treatment processes as a coagulant to clarify turbid water by precipitating impurities like suspended particles and organic matter. It is also employed in the papermaking industry as a sizing agent to improve paper strength and as a mordant in textiles for fixing dyes. Additionally, ferric alum finds applications in the pharmaceutical and cosmetic industries for its astringent properties and in food processing as a leavening agent in baking powders. However, like other aluminum and iron salts, ferric alum should be handled with care due to potential health hazards associated with excessive exposure or ingestion.