Seventeen samples from the Malenco serpentinite in the Swiss Alps, representing systematic prograde metamorphic conditions from prehnite-pumpellyite to upper amphibolite, are moderately to strongly magnetic (average susceptibility of 6.61¿10-2 SI units) due predominantly to the presence of a magnetite-rich spinel. Some greenschist facies samples contain the metal alloy awaruite (Ni3Fe); these contain in addition much greater amounts of magnetite. Small amounts of pyrrhotite in about half the samples complete the contributions to the total magnetization. Susceptibilities generally decrease with increasing metamorphic grade because of the production of increasing amounts of chrome-rich spinel which dilutes the magnetite component. These results indicate that significant magnetic anomalies should be generated in suture zones containing metamorphosed serpentinite and in areas where serpentinite is being actively subducted. ¿ American Geophysical Union 1988