The influence of a hybrid mineral additive which includes anthropogenic products-claydite dust and granulated blast-furnace slag in quantities of 20 and 30% of building gypsum mass-on the composition, structure and basic physical and mechanical properties of artificial stone on the basis of composite gypsum binder has been investigated.The incorporation of the hybrid mineral additive in combination with additives of lime and superplasticizer into the composition of building gypsum makes it possible to produce the artificial stone with more dense and fine-grained structure comparing with an initial binder without additives.The appearance of low-basic calcium hydro-silicates which fill the porous space, compact the stone structure, create additional contacts in the basic matrix, protect splices of gypsum crystals against dissolution is observed.The part of closed pores in the porous structure of stone on the basis of composite gypsum binder increases.Due to the incorporation of hybrid mineral additive the artificial stone on the basis of composite gypsum binder after 28 days of hardening under normal conditions has the compression strength of 30.5 Mpa, and softening index of 0.92.