The article considered the issues of the modification of gypsum stone to improve its performance properties. The influence of mineral additives on the physical and mechanical characteristics of the modified gypsum composition is described. The composition of the gypsum mixture included slaked lime and an aluminosilicate additive in the form of ash microspheres. It was isolated from ash and slag waste from fuel power plants as a result of their enrichment. This made it possible to reduce the carbon content in the additive to 3%. Modified compositions of the gypsum composition are proposed. The binder was replaced with an aluminosilicate microsphere. Hydrated lime was used to activate it. Its content varied: 0, 2, 4, 6, 8 and 10% of the weight of the gypsum binder. Replacing the binder with an aluminosilicate product for the enrichment of ash and slag mixtures made it possible to improve the structure of the stone and increase its operational properties. The compressive strength of the gypsum stone was 9 MPa. This is more than 100% higher than the strength of the control composition of gypsum stone. Studies have confirmed the effectiveness of using an aluminosilicate additive—a product of enrichment of ash and slag mixtures. The use of an aluminosilicate component for the production of modified gypsum mixtures allows the saving of gypsum resources. Developed formulations of gypsum compositions using aluminosilicate microspheres and chemical additives provide the specified performance properties. This makes it possible to use them in the production of self-leveling floors, plastering and puttying works. Replacing traditional compositions with a new composition based on waste has a positive effect on the preservation of the natural environment and contributes to the formation of comfortable conditions for human habitation.