We report a new class of resonant interactions of circularly polarized microwaves with powderedn‐type InSb, which is observed only in the cyclotron resonance inactive polarization, at magnetic fields independent of particle size. The new powder resonance is a multiparticle analog of the single‐particle magnetoplasma resonance first reported by Dresselhaus, Kip, and Kittel. Both the position and strength of the observed powder resonance are discussed quantitatively using the Rayleigh extinction cross section for a single particle.