A new method of leaching low-grade manganese ore (< 5% Mn) utilizing pyrite as a reagent was developed. By heating an aerated slurry of ore and pyrite and by recycling the leach liquor at controlled acidity to attack fresh ore, a manganous sulphate solution free of iron was obtained which when heated to about 175'C., yielded manganous sulphate monohydrate. During the leaching process, iron in the liquor was alter-