Infrared absorption in the direction of single crystal samples of gave a value for the energy gap at room temperature for indirect transitions of 0.45 ev with a temperature variation of . From resistivity, Hall coefficient and Seebeck coefficient data the energy gap at 0°K was calculated to be 0.57 ev, the mobility ratio 0.9, and the hole effective mass was found to increase with temperature from 0.2 to 0.38 between 100° and 300°K. The conductivity was found to be anisotropic, the three principal conductivities being in the ratio .