Magnetic transitions observed in sulfide minerals at elevated pressures and their geophysical significance.

The magnetic behavior of iron in chalcopyrite (CuFeS(2)) and pyrrhotite (Fe(7)S(8)) in the pressure range from 1 atmosphere to 20 kilobars has been studied by Mössbauer spectroscopy. Both chalcopyrite and pyrrhotite exhibit transitions from magnetically ordered to disordered states over the range from 5 to 16 kilobars. Both transitions, particularly the loss of ferrimagnetism in pyrrhotite, have geophysical consequences.