At the present time, the development of shielding screens from electromagnetic radiation based on composite carbon-containing materials through selecting the concentration and distribution of carbon and a binder has great application potential. Shungite rocks are a naturally occurring carbon-mineral composite with carbon content from 1 to 97%.This paper presents the results of the study of reflection from thin plates prepared from shungite rocks with different carbon contents (from 3 to 97 at.%) in the microwave radiation range of 8-12 GHz. The effect of the carbon content and distribution of the quartz in the carbon matrix on reflecting properties of shungites is characterized. The dynamic and static conductivity of shungite samples with a carbon content of 3-97% was calculated. Significant difference between static and dynamic conductivity for samples with the small carbon content was found.