• 1 Max-Planck-Institut für Molekulare Physiologie

We present the first experimental demonstration of intermittency in a granular medium. The medium consists of magnets embedded within spheres. These spheres are placed in a horizontal Petri dish where they roll by virtue of an alternating, homogenous magnetic field. Due to collisions with the wall, clustering leads to self-organization into ring pieces circulating along the wall. The intermi ttent behaviour consists of an aperiodical alternation of this circular motion with a gaslike state extended over the entire dish. Molecular dynamic simulations agree with observations