Tizapa mine is the polymetallic underground mine, which is located in the state of Mexico, Mexico. The mine utilizes the 3D ore body model for mining and exploration activities, which is composed of the data of surface/underground drillings and the geological mapping of stopes. It has been recognized that the significant inconsistency between the 3D ore body model and actual deposit in situ in recent years, therefore the division of exploration at Tizapa mine decided to revise and reconstruct the model. As a result, the new model which accommodates with actual ore body is generated. Tizapa’s drilling core logging procedure has been also improved, and the new direction of underground exploration is suggested by the new model.

The Spectral Induced Polarization method (SIP) is one of the electrical prospecting techniques using the alternating current of several frequencies, and makes it possible to obtain the electrical frequency characteristics of the underground by means of measuring the amplitude ratio and the phase difference between the transmitted current and the received voltage. This method has the possibility of identifying our target, namely useful minerals, judged from the IP effect which would be hardly distinguishable according to the conventional IP method. In order to verify the effectiveness of the SIP method in metal resource exploration, we conducted demonstration experiments in two areas which we can verify the results with the geological structure and the deposit model revealed by a lot of drillings or exploration tunnels. We applied a series of 3D analysis techniques including evaluation of the electromagnetic coupling, 3D complex resistivity inversion, Cole-Cole model parameter analysis, and classification of Cole-Cole model parameters. Consequently, it was demonstrated that the SIP method can acquire much information on subsurface electrical properties as compared with the conventional IP method and narrow the ranges of promising mineralized zones. In the course of reaching above outcome, however, erroneous interpretations of the results were occasionally caused. These matters were considered to stem from the inadequacy of the investigation depth or resolution against the size of the interested ore body. If we conduct measurement and analyses with careful treatment for these matters, there is a high possibility that the SIP method can enable us to classify subsurface mineralized zones and discover blind metal deposits with high reliability.