A 1.064 μm pumped Rb:PPKTP optical parametric oscillator (OPO) generates mid-IR radiation by intracavity mixing the resonant signal and idler waves in AgGaSe2. The ∼6 ns pulses at ∼7 μm have an energy of 670 μJ at 100 Hz, equivalent to an average power of 67 mW. The overall quantum conversion efficiency from 1.064 μm amounts to 8%, and the power conversion efficiency is 1.2%.