Fines in smelter grade aluminas are recognised as a significant process problem in aluminium smelting. However the understanding of the nature of this fine material and how it impacts on the reduction process are less clearly understood. The combination of new analytical methods such as Variable Pressure Scanning Electron Microscopy and very high field Solid State NMR provide new insights into the spatial distribution of phases within aluminas, and suggest how such fine materials are generated, particularly during calcination in the alumina refinery.