Amorphous calcium sulfate (ACS) is transitory phase in the precipitation of calcium sulfate minerals such as gypsum. ACS is also be present in mineral systems which may be relevant to the Martian surface. No detailed structural studies of ACS have been published. The present proposal would form part of a multi-technique structural study including also X-ray absorption spectroscopy and modelling. We wish to use SANDALS to measure the neutron diffraction structure factor of ACS. This can be analysed by peak fitting and by comparison with models using EPSR. The goal is to obtain the first detailed and realistic model of the structure of ACS.
