This paper discusses a particular mechanism for energy loss in granular media, involving sticking and sliding between grains at areas of contact. Earlier publications have developed expressions for attenuation in regular packings of spheres, attributing all the loss to sliding friction. The present work extends the model by incorporating static friction and thereby derives an expression for attenuation which is in better agreement with measured values. The attenuation coefficient for both shear and compressional waves is found to be: 1. Independent of vibration amplitude at low amplitudes; 2. Directly proportional to frequency; 3. Dependent on the difference between static and sliding coefficients of friction; and 4. Dependent on the packing of the granules.