Cangas and other types of supergene iron deposits show magnetic anomalies stronger than that corresponding to the big mass of itabirite and hematite from the Itabita ferriferous district, in Minas Gerais. The Màgnetic behaviour of these deposits is not related to their content of magnetite, but, most problably to the content of maghemite, a ferriferous supergene mineral of high magnetic susceptibility.
