Electrochemical analysis of highly reactive pyrite

Samples of highly reactive pyritic material, exposed during the construction of the Pennsylvania Interstate Highway 99 (I-99) has been characterized by X-ray diffraction, Raman microprobe spectroscopy, electron microscopy and electrochemical methods. Mineral standards of marcasite, arsenopyrite and pyrite were compared in order to determine the cause of rapid generation of acid and liberation of dissolved metals observed in the exposed pyritic material. Linear sweep voltammetry found no significant differences in the electrochemical activity, however, a significantly lower open circuit potential was found in the reactive pyrite material than in the pyrite or marcasite standards. A high concentration of zinc and aluminium impurities was observed in Energy Dispersive X-ray analysis of the finest iron sulfide crystals found in the reactive pyritic material.