Rates of change of magnetic susceptibility during leaching can characterize the presence of certain common types of magnetic minerals in metamorphic rocks. In this study the results of leaching are confirmed by mineal separation, optical microscopy, scanning electron microscopy (SEM) and microchemical analysis under SEM. Leaching curves provide a simple, rapid way of determining the relative roles of oxides, sulfides, and silicates in carrying the susceptibility in metamorphic rocks. ¿ American Geophysical Union 1990