“…The position of the miscibility gap was given with 59.3-76.8 mol% SiO 2 , corresponding to 41-62 mass-% SiO 2 at 2250 • C while the composition of the critical point was 69.8 mol%/53 mass-% SiO 2 at 2430 • C. Fig. 1 presents a re-drawn version of this phase diagram [7] which additionally contains the positions of the originally measured points. It should be pointed out that Toropov & Galakhov also used the unproven solid solubility of SiO 2 in ZrO 2 as proposed by Zhirnova and Curtis & Sowman. Surprisingly, all phase diagrams and thermodynamic data sets published later make use of these quite early results without any own experimental evidence regarding the liquidus surface, e.g.…”