Polymorphic transformation II → I in potassium nitrate: multiple orientations

Abstract

The crystal structural transformation from aragonite-type KNO₃I produces a variety of orientations as shown by polarized light microscopy. Extinction directions are listed and include one which is consistent with the reported orientation for CaCO₃ and one consistent with another orientation previously reported for KNO₃. Interfaces are produced parallel to the pseudohexagonal basal plane of 11, but the basal planes of the two phases do not necessarily form the interface.