The invention relates to an aeronautical part, such as, for example, a turbine blade or a distributor vane, which is used in aeronautics, comprising at least one reactive layer adapted to react with at least one CMAS compound, the reactive layer at least partially covering the environmental barrier, characterized in that the material of the reactive layer comprises at least one oxide of the formula A′4-xA″xB′2-yB″yO11-δ, A′ being selected from a rare earth, yttrium and scandium, A″ being selected from a rare earth, yttrium, scandium and aluminum, B′ being selected from tantalum and niobium, B″ being selected from tantalum, niobium, titanium, zirconium, hafnium, aluminum and cesium, wherein x and y are real numbers between 0 and 2 and 6 is a real number between −1 and 2 and preferably between −1 and 1.