This article contains the results of research into the effects of pyrophyllite on the properties of dinas refractories and is aimed at studying the possibility of extending the re~ serves of quartzite raw materials for their production.Pyrophyllite 3 AI203-4SiO='H20 [I] belongs to the micaceous group of materials~ Its chemical composition, %* is: A1203 28.3, Si02 66.7, H20 5.0. Impurities are en=ountered as MgO (up to 9%), FeO (up to 5%), Fe=O3, CaO, alkalies, and titania, Pyrophyllite normally consists of plate-rod accumulations or aggregates or cryptop!atelet, dense rocks, The mineral is white with yellow or pale green shades; it has a glassy shine with mother-of-pearl shades or pale-green shades; it is greasy to the touch, with a hardness of about i, Ng = 1.600, Np = 1.552, and N m = 1.588. The cleavage is excellent.The density is 2.66-2,90 g/cm 3.Pyrophyllite is encountered in association with quartz, carbonates, hematite, and other minerals formed as a result of the hydrothermal decomposition of ordinary acid~ igneous rocks; it is observed in metamorphic slates. During heat treatment pyrophyllite shows an endothermic effect at 710-800~ as a result of the dehydration [2] (according to data in [3] at 600-800~ and can be used as an independent refractory material.*Here and subsequently mass proportions are indicated.