TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Processes: Silica contents of below 0.05 wt.% are achieved by using 2 or more stages. The HF is used as a 1-50 wt.% aqueous solution and the silica dissolution is effected by stirring or rotating an aqueous suspension of the dissociated silicate and the HF at 0-95 degrees C. The dissociated silicate having been obtained by melting the silicate in an induction melting furnace with a sintering crust crucible at above 1,760 (especially 2,400-3,000) degrees C and then quenching with a gas and/or water. The monoclinic form is obtained from Zr silicate dissociated by heating at 2,500-3,000 degrees C and the tetragonal form from silicate dissociated by heating at 1,760-2,000 degrees C. Cubic form ZrO2 containing the stabilizing oxides or silicates used in the production process is obtained using silicate dissociated in the presence of MgO, CaO, SrO, Se2O3, Y2O3, La2O3 or LaO2 at 2,500-3,000 degrees C.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Product: The monoclinic form is obtained from Zr silicate dissociated by heating at 2,500-3,000 degrees C and the tetragonal form from silicate dissociated by heating at 1,760-2,000 degrees C. Cubic form ZrO2 containing the stabilizing oxides or silicates used in the production process is obtained using silicate dissociated in the presence of MgO, CaO, SrO, Se2O3, Y2O3, La2O3 or LaO2 at 2,500-3,000 degrees C.    TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Processes: Silica contents below 0.05 wt.% are achieved by using 2 or more stages. The HF is used as a 1-50 wt.% aqueous solution and the silica dissolution is effected by stirring or rotating an aqueous suspension of the dissociated silicate and the HF at 0-95 degrees C, the dissociated silicate having been obtained by melting the silicate in an induction melting furnace with a sintering crust crucible at above 1,760 (especially 2,400-3,000) degrees C and then quenching with a gas and/or water. The monoclinic form is obtained from Zr silicate dissociated by heating at 2,500-3,000 degrees C and the tetragonal form from silicate dissociated by heating at 1,760-2,000 degrees C. Cubic form ZrO2 containing the stabilizing oxides or silicates used in the production process is obtained using silicate dissociated in the presence of MgO, CaO, SrO, Se2O3, Y2O3, La2O3 or LaO2 at 2,500-3,000 degrees C. EXAMPLE - ZrO2 with a silica content below 0.05 wt.% was obtained from Zr silicate of 33% silica content (obtained by dissociation in an inductive melting furnace as per EP501143 by (i) portion-wise suspending the silicate (100g) in a mixture of 38-40% HF (175g) and water (70g), (ii) stirring for 2 hours and diluting with water (1,500ml), (iii) deposing the solids and removing the supernatant, (iv) adding 38-40% HF (83g) and water (70ml) and stirring for 2 hours and then (v) washing and drying the product.