Boehmite exsolution in corundum

The pronounced parting observed in much corundum has traditionally been attributed to twinning. This study identifles boehmite as occurring in seams along the {IOTU Parting directions. Corundum's parting is, therefore, due to the weakness of the boehmite-corundum contact. The boehmite is believed to be a product of exsolution.