We report tuning range and efficiency measurements of a novel dual-gain medium Brillouin/erbium fiber laser which utilizes the Brillouin gain in single-mode optical fiber and gain in erbium-doped fiber. Analytical results on the efficiency of the laser are presented which fit well to the experimental results and allow for an intuitive interpretation of the observed properties of the laser efficiency, which varies according to the laser operating conditions. Tuning range of 4nm was observed upon tuning of the Brillouin pump wavelength.