Electric and Magnetic Properties of Bornite, Cu5FeS4: With a Review of the Physical Properties of Cu-Fe-S Minerals

The electric and magnetic properties of synthetic and natural bornites are considered to be in an intimate relation to transformation of their crystal structures.
It has become evident that the electric conductivity reveals increment in its value with increasing temperature and anomalous changes at 180°C and 300°C where transformation from the low-temperature tetra-gonal form to the transitional intermediate one and that from the intermediate to the high-temperature cubic one are assumable to appear, the substance under consideration is a typical semiconductor with activa-tion energy of 0.25～0.35 eV in case of the low form and 0.54 eV in case of the high form, the magnetic susceptibility decreases paramagnetically with increasing temperature and shows anomalies at the temperature mentioned above and applying Curie-Weiss law to the susceptibility versus temperature curves below 180°C, it is possible to obtain 6.68μB as the effective Bohr magneton number and -664°K for the asymptotic Curie temperature, respectively.
The electric and magnetic properties have been discussed in connection with those of Cu-Fe-S minerals such as FeSx, FeS2, CuS, Cu2S, CuFeS2, and CuFe2S3.