TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Conditions: The pH of iron-containing sulfuric acid acidic water which is industrial effluent or anti-waste water is adjusted to less than 3.Preferred Materials: The alkaline earth type material is calcium or magnesium, hydroxide, carbonate and/or silicate, calcium-silicate board crushed material, limestone, calcium silicate, calcium silicate group mineral or artificial material, tobermorite, xonolite, rock wool, glass wool, nickel slag wool, cement, cement clinker, concrete, mortar, iron-manufacturing slag, non-ferrous slag, fly ash and/or zeolite, and powder chosen from waste material, particulate material, lump, fibrous material or crushed material. Iron-type material is a hydrated iron-type compound chosen from siderite, ankerite, goethite, scale iron ore, light, hydrated iron oxide, ferrihydrite, magnetic iron ore, hematite, maghemite, limonite and/or metal waste water treatment field iron containing neutralization deposit.Preferred Method: Alternately, iron-containing sulfuric acid acidic water having pH of less than 3 is made to contact with pH adjustment material. The pH of the iron-containing sulfuric acid acidic water is adjusted to pH of 2.5-4 by increasing the pH to 0.5 or more. Schwertmannite is precipitated or aggregated naturally without adding polymer flocculent, in iron-containing sulfuric acid acidic water when maintained for 0.5 hr or more in the presence of iron bacterium. 50% schwertmannite having solid content of 5% is collected. Further, schwertmannite is manufactured by pouring iron containing sulfuric acid acidic water to a flowpath or retention basin for a predetermined time so that schwertmannite is formed. The schwertmannite is collected at predetermined intervals from the flow path or bottom of retention basin. EXAMPLE - Iron-containing sulfuric acid water having pH of 1.8, and containing total iron content (in mg/l) (370), iron ion (Fe2+) (370), sulfate ion (SO42-) (2510) was produced using ferrous sulfate, sulfuric acid and gypsum reagent, and stirred for 30 minutes after adding hydrated iron oxide of calcium hydroxide powder as pH adjustment material, calcium carbonate, cement, rock wool. The pH of the solution was adjusted to 2.5-4, and filtered. Thiobacillus ferooxidan was added to the filtrate and the solution was analyzed by X-ray powder diffractor. High purity schwertmannite having low crystallinity was formed and collected.