Mineralogical analyses of atmospheric particulates collected on filter media have been performed by X-ray diffraction (XRD). The low peak intensity/background ratio commonly found in the XRD analysis of dust deposited on filters is improved by the use of other different supporting media. Membrane filters with atmospheric dust have been directly analyzed by X-ray diffraction and then extracted from filter and deposited on three different substrates for analysis: glass slides, silver membrane filters and silicon plates cut parallel to (510) crystalline planes. The same procedures were carried out using a clay mineral standard (illite, <2m). The use of low-background silicon (510) plates offers the best results, improving net peak intensities and peak/background ratio. (C) 2001 Elsevier Science Ltd. All rights reserved.