A fusion-cast refractory product based on zirconium dioxide is provided. The zirconium dioxide crystals are stabilized by magnesium oxide and surrounded by at least one magnesium oxide-containing crystalline phase. The content of magnesium oxide-containing crystalline phases, relative to the total mass of the product, amounts to 1 to 8 wt. %. In an example, the stabilized zirconium dioxide crystals are surrounded by at least one of the following magnesium oxide-containing crystalline phases: forsterite, enstatite, cordierite or spinel.