This report presents the variations of the electrical conductivity and the migration of natural pyrite impurity levels at temperatures range from 298 to 573 K and pressures range from 1 atm. to 20.9 GPa. The electrical conductivity increases with temperature at a fixed pressure, displaying the semiconductor behavior of the sample. In spite of the positive correlations of electrical conductivity and pressure, there exists an acceleration in the rate of conductivity increase after similar to 13 GPa. No indication of a chemical reaction or structural phase transition of pyrite was detected by Raman spectroscopy. The main trace elements that affect the electrical properties of pyrite are determined by inductively coupled plasma with mass spectrometry (ICPMS). The transport activation energy of natural pyrite is similar to 0.045 eV at ambient pressure, which corresponds to the activation of the Co-Fe donor level (similar to 1/2 E (D)), and decreases with increasing pressure.