This paper presents the results of experimental determinations concerning electromagnetic field attenuation in materials containing micro-particles of ashes pyrite in their structure. To know the effect of shielding effectiveness of electromagnetic field electromagnetic absorbents were performed by transmission measurements of attenuation in the frequency range 1-18 GHz. The goal of present paper consits in the realization a composit material with polymeric matrix. The synthetic polymeric matrix used at the obtaining composite is represented by a bicomponent silicone elastomer that strengthens itself at the room temperature by means of a poly condensation reaction. The materials obtained in laboratory contain plated nettling like reinforcement material and ashes pyrite as filling agent. The materials were characterized by X-ray diffraction, transmision diminishing carried out and relative permittivity.