Dissolution of commercial white fused and tabular Al2O3 grains into a model silicate slag was investigated after 1 h at 1450 degrees and 1600 degrees C. Formation of CA(6) and hercynitic spinel layers was observed at all Al2O3/slag interfaces. The spinel layer was not always continuous, and so, compared with the CA(6) layer, it had a less-significant effect on the dissolution process. The CA(6) layer that formed adjacent to the tabular Al2O3 was incomplete at both temperatures, so that its dissolution was not a totally indirect process. These incomplete CA(6) and spinel layers meant that slag penetrated into the tabular Al2O3 grains, which, thus, were corroded and disintegrated by the penetrating slag. There was evidence of liquid in the CA(6) layer adjacent to the fused Al2O3 after 1 h at 1450 degrees C, which also enabled direct dissolution. After 1 h at 1600 degrees C, fused Al2O3 revealed a thick (similar to 60 mu m), continuous and unpenetrated CA(6) layer, indicating fully indirect dissolution at this temperature.