We present measurements of the scattering angle distribution of the whole scattering matrix for randomly oriented particles of three mineral samples: fly ash, green clay, and red clay at 442 and 633 nm. Fly ash consists of aggregates of nearly spherical particles while green clay and red clay particles represent irregular compact particles. We compare the measured results for fly ash with an experimentally determined average scattering matrix which is based on measurements for a broad selection of irregular mineral aerosol particles. We find that the scattering matrix of our polydisperse sample of aggregates of nearly spherical particles differs considerably from that of compact particles. In addition, the angular distribution of the elements of the scattering matrix (except F22(&thgr;)/F11(&thgr;)) for fly ash particles seem to be dominated by the single monomers. The effects of small differences in composition on the scattering behavior have also been studied by comparing our experimental results for green clay particles with those obtained by Volten et al. <2001> for red clay particles at the same wavelengths. ¿ 2001 American Geophysical Union