Silicon-aluminium distribution in dehydrated calcium heulandite

The distribution of aluminium within the lattice of a model calcium heuland ite is considered. Significant segregation of Al to particular sites is not ed with T2 being preferentially occupied whereas T4 has a low Al occupancy. T5 is also occupied, in contrast to earlier work on Na-clinoptilolite. The resulting distributions are also significantly different to previous work on Na-clinoptilolite, demonstrating the influence of the Si/Al ratio and ca tion species on the spatial arrangement of Si and Al in the framework.