The Kaolinite‐Mullite Reaction Series: II, Metakaolin

By applying single‐crystal X‐ray techniques, it is shown that kaolinite transforms to meta‐kaolin and subsequently to a cubic spinel‐type phase by a process of orderlyrecrystallization. The dimensional and directional relations between the phases are established. On the basis of this information, together with the density of metakaolin, a crystal structure is suggested for metakaolin. X‐ray examination of partly transformed kaolinite provides evidence for some long‐range regularity in the transformation process which is not shown by microcrystalline kaolinite.